# Pre-Reconnaissance Report

## Port Discovery (naabu)
Status: Skipped
[object Object]

## Network Scanning (nmap)
Status: success
Starting Nmap 7.97 ( https://nmap.org ) at 2025-10-29 20:13 -0700
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000028s latency).
Other addresses for localhost (not scanned): ::1
Not shown: 993 closed tcp ports (conn-refused)
PORT      STATE SERVICE   VERSION
80/tcp    open  http      Caddy httpd
|_http-title: Site doesn't have a title.
|_http-server-header: Caddy
443/tcp   open  ssl/https
|_http-title: Site doesn't have a title.
631/tcp   open  ipp       CUPS 2.3
|_http-title: Home - CUPS 2.3.4
|_http-server-header: CUPS/2.3 IPP/2.1
4444/tcp  open  http      SimpleHTTPServer 0.6 (Python 3.12.10)
| http-git: 
|   127.0.0.1:4444/.git/
|     Git repository found!
|     .git/config matched patterns 'user'
|     Repository description: Unnamed repository; edit this file 'description' to name the...
|_    Last commit message: \xE2\x9C\x85 Executive Summary and Report Cleanup: completed successf...
|_http-title: Directory listing for /
|_http-server-header: SimpleHTTP/0.6 Python/3.12.10
9998/tcp  open  http      SimpleHTTPServer 0.6 (Python 3.12.10)
| uptime-agent-info: <!DOCTYPE HTML>
| <html lang="en">
|     <head>
|         <meta charset="utf-8">
|         <title>Error response</title>
|     </head>
|     <body>
|         <h1>Error response</h1>
|         <p>Error code: 400</p>
|         <p>Message: Bad request syntax ('sysinfo').</p>
|         <p>Error code explanation: 400 - Bad request syntax or unsupported method.</p>
|     </body>
|_</html>
| http-git: 
|   127.0.0.1:9998/.git/
|     Git repository found!
|     .git/config matched patterns 'user'
|     Repository description: Unnamed repository; edit this file 'description' to name the...
|_    Last commit message: \xE2\x9C\x85 Executive Summary and Report Cleanup: completed successf...
|_http-title: Directory listing for /
|_http-server-header: SimpleHTTP/0.6 Python/3.12.10
9999/tcp  open  abyss?
| fingerprint-strings: 
|   DNSStatusRequestTCP, DNSVersionBindReqTCP, Help, JavaRMI, Kerberos, RPCCheck, SMBProgNeg, SSLSessionReq, TLSSessionReq, TerminalServerCookie: 
|     HTTP/1.1 400 Bad Request
|     Connection: close
|   FourOhFourRequest, GetRequest: 
|     HTTP/1.1 200 OK
|     Access-Control-Allow-Origin: *
|     Access-Control-Allow-Methods: GET, POST, OPTIONS
|     Access-Control-Allow-Headers: Content-Type
|     Content-Type: text/plain
|     Date: Thu, 30 Oct 2025 03:13:39 GMT
|     Connection: close
|   HTTPOptions: 
|     HTTP/1.1 200 OK
|     Access-Control-Allow-Origin: *
|     Access-Control-Allow-Methods: GET, POST, OPTIONS
|     Access-Control-Allow-Headers: Content-Type
|     Date: Thu, 30 Oct 2025 03:13:39 GMT
|     Connection: close
|   RTSPRequest: 
|     HTTP/1.1 200 OK
|     Access-Control-Allow-Origin: *
|     Access-Control-Allow-Methods: GET, POST, OPTIONS
|     Access-Control-Allow-Headers: Content-Type
|     Date: Thu, 30 Oct 2025 03:13:44 GMT
|_    Connection: close
49152/tcp open  http      Golang net/http server
| fingerprint-strings: 
|   FourOhFourRequest, GetRequest, HTTPOptions: 
|     HTTP/1.0 401 Unauthorized
|     Content-Security-Policy: default-src 'none'; frame-ancestors 'none'; script-src 'none'; script-src-elem 'none'; script-src-attr 'none'
|     Content-Type: text/plain; charset=utf-8
|     Tailscale-Cap: 115
|     Tailscale-Version: 1.82.5-tdec88625e-gec2eb9730
|     X-Content-Type-Options: nosniff
|     X-Frame-Options: DENY
|     Date: Thu, 30 Oct 2025 03:13:39 GMT
|     Content-Length: 14
|     auth required
|   GenericLines, Help, RTSPRequest: 
|     HTTP/1.1 400 Bad Request
|     Content-Type: text/plain; charset=utf-8
|     Connection: close
|_    Request
|_http-title: Site doesn't have a title (text/plain; charset=utf-8).
| http-auth: 
| HTTP/1.1 401 Unauthorized\x0D
|_  Server returned status 401 but no WWW-Authenticate header.
2 services unrecognized despite returning data. If you know the service/version, please submit the following fingerprints at https://nmap.org/cgi-bin/submit.cgi?new-service :
==============NEXT SERVICE FINGERPRINT (SUBMIT INDIVIDUALLY)==============
SF-Port9999-TCP:V=7.97%I=7%D=10/29%Time=6902D7E3%P=arm-apple-darwin24.4.0%
SF:r(GetRequest,E5,"HTTP/1\.1\x20200\x20OK\r\nAccess-Control-Allow-Origin:
SF:\x20\*\r\nAccess-Control-Allow-Methods:\x20GET,\x20POST,\x20OPTIONS\r\n
SF:Access-Control-Allow-Headers:\x20Content-Type\r\nContent-Type:\x20text/
SF:plain\r\nDate:\x20Thu,\x2030\x20Oct\x202025\x2003:13:39\x20GMT\r\nConne
SF:ction:\x20close\r\n\r\nOK")%r(HTTPOptions,C9,"HTTP/1\.1\x20200\x20OK\r\
SF:nAccess-Control-Allow-Origin:\x20\*\r\nAccess-Control-Allow-Methods:\x2
SF:0GET,\x20POST,\x20OPTIONS\r\nAccess-Control-Allow-Headers:\x20Content-T
SF:ype\r\nDate:\x20Thu,\x2030\x20Oct\x202025\x2003:13:39\x20GMT\r\nConnect
SF:ion:\x20close\r\n\r\n")%r(FourOhFourRequest,E5,"HTTP/1\.1\x20200\x20OK\
SF:r\nAccess-Control-Allow-Origin:\x20\*\r\nAccess-Control-Allow-Methods:\
SF:x20GET,\x20POST,\x20OPTIONS\r\nAccess-Control-Allow-Headers:\x20Content
SF:-Type\r\nContent-Type:\x20text/plain\r\nDate:\x20Thu,\x2030\x20Oct\x202
SF:025\x2003:13:39\x20GMT\r\nConnection:\x20close\r\n\r\nOK")%r(JavaRMI,2F
SF:,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nConnection:\x20close\r\n\r\n")%
SF:r(RTSPRequest,C9,"HTTP/1\.1\x20200\x20OK\r\nAccess-Control-Allow-Origin
SF::\x20\*\r\nAccess-Control-Allow-Methods:\x20GET,\x20POST,\x20OPTIONS\r\
SF:nAccess-Control-Allow-Headers:\x20Content-Type\r\nDate:\x20Thu,\x2030\x
SF:20Oct\x202025\x2003:13:44\x20GMT\r\nConnection:\x20close\r\n\r\n")%r(RP
SF:CCheck,2F,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nConnection:\x20close\r
SF:\n\r\n")%r(DNSVersionBindReqTCP,2F,"HTTP/1\.1\x20400\x20Bad\x20Request\
SF:r\nConnection:\x20close\r\n\r\n")%r(DNSStatusRequestTCP,2F,"HTTP/1\.1\x
SF:20400\x20Bad\x20Request\r\nConnection:\x20close\r\n\r\n")%r(Help,2F,"HT
SF:TP/1\.1\x20400\x20Bad\x20Request\r\nConnection:\x20close\r\n\r\n")%r(SS
SF:LSessionReq,2F,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nConnection:\x20cl
SF:ose\r\n\r\n")%r(TerminalServerCookie,2F,"HTTP/1\.1\x20400\x20Bad\x20Req
SF:uest\r\nConnection:\x20close\r\n\r\n")%r(TLSSessionReq,2F,"HTTP/1\.1\x2
SF:0400\x20Bad\x20Request\r\nConnection:\x20close\r\n\r\n")%r(Kerberos,2F,
SF:"HTTP/1\.1\x20400\x20Bad\x20Request\r\nConnection:\x20close\r\n\r\n")%r
SF:(SMBProgNeg,2F,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nConnection:\x20cl
SF:ose\r\n\r\n");
==============NEXT SERVICE FINGERPRINT (SUBMIT INDIVIDUALLY)==============
SF-Port49152-TCP:V=7.97%I=7%D=10/29%Time=6902D7E3%P=arm-apple-darwin24.4.0
SF:%r(FourOhFourRequest,192,"HTTP/1\.0\x20401\x20Unauthorized\r\nContent-S
SF:ecurity-Policy:\x20default-src\x20'none';\x20frame-ancestors\x20'none';
SF:\x20script-src\x20'none';\x20script-src-elem\x20'none';\x20script-src-a
SF:ttr\x20'none'\r\nContent-Type:\x20text/plain;\x20charset=utf-8\r\nTails
SF:cale-Cap:\x20115\r\nTailscale-Version:\x201\.82\.5-tdec88625e-gec2eb973
SF:0\r\nX-Content-Type-Options:\x20nosniff\r\nX-Frame-Options:\x20DENY\r\n
SF:Date:\x20Thu,\x2030\x20Oct\x202025\x2003:13:39\x20GMT\r\nContent-Length
SF::\x2014\r\n\r\nauth\x20required\n")%r(GenericLines,67,"HTTP/1\.1\x20400
SF:\x20Bad\x20Request\r\nContent-Type:\x20text/plain;\x20charset=utf-8\r\n
SF:Connection:\x20close\r\n\r\n400\x20Bad\x20Request")%r(GetRequest,192,"H
SF:TTP/1\.0\x20401\x20Unauthorized\r\nContent-Security-Policy:\x20default-
SF:src\x20'none';\x20frame-ancestors\x20'none';\x20script-src\x20'none';\x
SF:20script-src-elem\x20'none';\x20script-src-attr\x20'none'\r\nContent-Ty
SF:pe:\x20text/plain;\x20charset=utf-8\r\nTailscale-Cap:\x20115\r\nTailsca
SF:le-Version:\x201\.82\.5-tdec88625e-gec2eb9730\r\nX-Content-Type-Options
SF::\x20nosniff\r\nX-Frame-Options:\x20DENY\r\nDate:\x20Thu,\x2030\x20Oct\
SF:x202025\x2003:13:39\x20GMT\r\nContent-Length:\x2014\r\n\r\nauth\x20requ
SF:ired\n")%r(HTTPOptions,192,"HTTP/1\.0\x20401\x20Unauthorized\r\nContent
SF:-Security-Policy:\x20default-src\x20'none';\x20frame-ancestors\x20'none
SF:';\x20script-src\x20'none';\x20script-src-elem\x20'none';\x20script-src
SF:-attr\x20'none'\r\nContent-Type:\x20text/plain;\x20charset=utf-8\r\nTai
SF:lscale-Cap:\x20115\r\nTailscale-Version:\x201\.82\.5-tdec88625e-gec2eb9
SF:730\r\nX-Content-Type-Options:\x20nosniff\r\nX-Frame-Options:\x20DENY\r
SF:\nDate:\x20Thu,\x2030\x20Oct\x202025\x2003:13:39\x20GMT\r\nContent-Leng
SF:th:\x2014\r\n\r\nauth\x20required\n")%r(RTSPRequest,67,"HTTP/1\.1\x2040
SF:0\x20Bad\x20Request\r\nContent-Type:\x20text/plain;\x20charset=utf-8\r\
SF:nConnection:\x20close\r\n\r\n400\x20Bad\x20Request")%r(Help,67,"HTTP/1\
SF:.1\x20400\x20Bad\x20Request\r\nContent-Type:\x20text/plain;\x20charset=
SF:utf-8\r\nConnection:\x20close\r\n\r\n400\x20Bad\x20Request");

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 34.75 seconds


## Subdomain Discovery (subfinder)
Status: success
www.localhost
server02.counterintel.localhost
mail02.regency.localhost
mail03.regency.localhost
owa.regency.localhost
sbs.allsaintsschool.localhost
exchvm.nwcnet.localhost
mail.localhost
tools.sonoma.edu.localhost
autodiscover.localhost
mse-ca-mail.corp.mse.localhost
autodiscover.regency.localhost
mail.regency.localhost
naeu2.naeuinc.localhost
fndlync01.5ninesdata.localhost
server2.hunter.localhost


## Technology Detection (whatweb)
Status: success
[1m[34mhttp://localhost:33029[0m [200 OK] [1mHTML5[0m, [1mHTTPServer[0m[[1m[36mWerkzeug/3.0.6 Python/3.8.20[0m], [1mIP[0m[[0m[22m::1[0m], [1mPasswordField[0m[[0m[22mpassword[0m], [1mPython[0m[[1m[32m3.8.20[0m], [1mWerkzeug[0m[[1m[32m3.0.6[0m]

## Code Analysis
# Penetration Test Scope & Boundaries

**Primary Directive:** This analysis is strictly limited to the **network-accessible attack surface** of the application. All findings and recommendations adhere to this scope and focus exclusively on components reachable via network requests.

### In-Scope: Network-Reachable Components
A component is considered **in-scope** if its execution can be initiated, directly or indirectly, by a network request that the deployed application server is capable of receiving. This includes:
- Publicly exposed web pages and API endpoints (`/`, `/login`, `/welcome`)
- Endpoints requiring authentication via the application's standard login mechanisms
- Any developer utility, debug console, or script that has been mistakenly exposed through a route or is otherwise callable from other in-scope, network-reachable code
- Background jobs or async tasks that can be triggered by network requests (none identified in this application)

### Out-of-Scope: Locally Executable Only
A component is **out-of-scope** if it **cannot** be invoked through the running application's network interface and requires an execution context completely external to the application's request-response cycle. For this application, the following are explicitly out of scope:
- **Build tools:** Makefile, Docker build scripts
- **Infrastructure configuration:** docker-compose.yml, Dockerfile (analyzed only for security configuration impacts)
- **Development scripts:** start.sh (unused container entrypoint script)
- **Dependency manifests:** requirements.txt (analyzed only for vulnerable dependencies)

---

## 1. Executive Summary

This Flask-based web application (XBEN-103-24) is a deliberately vulnerable Capture The Flag (CTF) challenge designed to demonstrate cryptographic weaknesses, specifically **AES-CBC padding oracle vulnerabilities**. The application implements a custom session management system using AES-256-CBC encryption with critical flaws that allow complete session takeover and privilege escalation.

**Critical Security Posture:** The application exhibits **CRITICAL-severity vulnerabilities** across all security domains. The primary attack vector is a **padding oracle vulnerability** in the custom AES-CBC encryption implementation, which allows an attacker to decrypt arbitrary session cookies, forge admin sessions, and access sensitive flag data without knowing valid credentials. Additional critical issues include the complete absence of transport layer security (HTTP only), missing session cookie security flags, hardcoded credentials in source code, extensive debug logging of sensitive data, and Flask debug mode enabled in production.

**Attack Surface Summary:** The application exposes three network-accessible HTTP endpoints on port 8000 (mapped to host port 33029). Two endpoints are publicly accessible without authentication (`GET /` for login page, `POST /login` for authentication), and one endpoint requires a valid encrypted session cookie (`GET /welcome` for flag retrieval). The application runs in a single Docker container with no external service dependencies, database connections, or outbound network requests, creating a minimal but highly vulnerable attack surface focused on cryptographic exploitation.

**Architectural Risk:** The application's security architecture relies entirely on a custom AES-CBC encryption implementation with multiple severe flaws: null byte padding instead of PKCS#7, no message authentication code (HMAC/GCM), exception-based error disclosure, and ephemeral key generation. These design decisions create a textbook padding oracle scenario where attackers can decrypt and forge session cookies through iterative byte-by-byte manipulation. The win condition is straightforward: bypass authentication to access the admin account and retrieve the flag from `/flag.txt`.

---

## 2. Architecture & Technology Stack

### Framework & Language
**Flask 3.0.3** running on **Python 3.8.20** within a containerized environment based on the `python:3.8-slim` Docker image (Debian Bookworm). The application uses Flask's built-in Werkzeug development server, which is explicitly **not production-ready** and lacks critical security hardening features such as request rate limiting, connection pooling, and proper error handling. The development server is configured with `debug=True` (line 74 of `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py`), exposing an interactive debugger with potential remote code execution capabilities through the Werkzeug debug console.

**Security Implications of Technology Choices:**
1. **Werkzeug Development Server:** The application uses `app.run(debug=True, host='0.0.0.0', port=8000)`, which exposes the application on all network interfaces without production-grade security controls. This configuration is suitable only for local development and introduces severe risks including: unthrottled request processing (enabling brute-force and padding oracle attacks), detailed stack traces exposed to clients (information disclosure), and the Werkzeug debugger console accessible via PIN bypass vulnerabilities.

2. **Python Cryptography Library (42.0.8):** While the `cryptography` library itself is a reputable, well-maintained implementation of cryptographic primitives, the application implements a **custom encryption wrapper** that negates all security benefits. The use of low-level cipher primitives (`Cipher`, `algorithms.AES`, `modes.CBC`) without proper authenticated encryption (AEAD) creates exploitable vulnerabilities. The application should have used high-level constructs like `Fernet` (symmetric encryption with authentication) or `AESGCM` (AES-Galois/Counter Mode with built-in authentication).

### Architectural Pattern
**Monolithic Web Application** with server-side rendered templates (Jinja2). The application follows a traditional three-tier architecture collapsed into a single process:

1. **Presentation Layer:** Jinja2 HTML templates (`index.html` for login form, `welcome.html` for authenticated user display) with static CSS (`style.css`). Jinja2's autoescape feature is enabled by default, providing baseline XSS protection for template rendering.

2. **Application Layer:** Flask route handlers implementing authentication logic (`/login`), session management (custom AES-CBC encryption/decryption functions), and authorization checks (simple username string comparison for admin access).

3. **Data Layer:** No persistent storage. User credentials are hardcoded in an in-memory Python dictionary (`users = {"test1": "test1", "admin": "somehardpassword"}`), and session state is stored client-side in encrypted cookies.

**Trust Boundary Analysis:**
The primary trust boundary exists between the client (web browser) and the server (Flask application). The application attempts to maintain session integrity through encryption, but the lack of message authentication means this boundary is completely permeable. Key trust boundary vulnerabilities include:

- **Unauthenticated Ciphertext:** Session cookies are encrypted but not authenticated (no HMAC), allowing attackers to manipulate ciphertext without detection. This violates the fundamental principle that encryption alone does not provide integrity.

- **Client-Side Session Storage:** All session state is stored in client-controlled cookies, making the application vulnerable to replay attacks, session fixation, and cookie manipulation. The ephemeral encryption key (regenerated on each restart) provides no persistent session security.

- **No Network Encryption:** HTTP-only communication means all data (credentials, session cookies, flag values) crosses the trust boundary in cleartext, allowing trivial man-in-the-middle attacks.

### Critical Security Components

**1. Authentication System (Lines 42-51):**
The authentication mechanism is a simple form-based login with POST to `/login`. Credentials are validated through plaintext dictionary lookup (`if username in users and users[username] == password`) with **no password hashing**. This violates security best practices:
- **No bcrypt/Argon2/PBKDF2:** Passwords should never be compared in plaintext
- **Timing Attack Vulnerability:** String comparison leaks information about password validity through response timing
- **Hardcoded Credentials:** Admin password "somehardpassword" is committed to source code (line 15)

**2. Session Management (Lines 18-36, 48-49):**
The application implements a custom session management system using AES-256-CBC encryption for session cookies. Session workflow:

```
Login → encrypt_data(username) → session cookie (hex-encoded IV+ciphertext) → 
Request /welcome → decrypt_data(cookie) → render username → flag disclosure if admin
```

**Critical Cryptographic Flaws:**

- **Ephemeral Key Generation (Line 10):** `key = os.urandom(32)` generates a new 256-bit AES key on application startup. This key exists only in process memory and is lost on restart, invalidating all existing sessions. No key persistence or derivation mechanism exists.

- **Custom Null Byte Padding (Lines 20-21, 35):** Instead of PKCS#7 standard padding, the application implements custom padding with null bytes:
  ```python
  # Encryption padding
  padding_length = 16 - (len(data) % 16)
  padded_data = data.encode() + b'\x00' * padding_length
  
  # Decryption unpadding
  plaintext = padded_plaintext.rstrip(b'\x00')
  ```
  This creates an exploitable padding oracle because: (a) usernames ending in null bytes will be incorrectly truncated, (b) error messages differ between padding failures and decryption failures, (c) the padding scheme is deterministic and manipulable.

- **No Message Authentication Code (Lines 22-24, 30-32):** The application uses raw AES-CBC without HMAC or authenticated encryption (AES-GCM). This allows:
  - **Padding oracle attacks:** Attacker can iteratively decrypt ciphertext by observing error responses
  - **Bit-flipping attacks:** Attacker can modify plaintext by XORing ciphertext blocks
  - **Ciphertext malleability:** No integrity verification allows arbitrary ciphertext manipulation

- **Exception-Based Error Disclosure (Line 70):** The decryption error handler returns raw exception messages to the client (`return str(e)`), creating a perfect padding oracle. Different exception types reveal whether padding validation failed versus decryption failed, enabling byte-by-byte plaintext recovery.

**3. Authorization Model (Lines 63-65):**
Authorization is implemented as a simple string comparison: `if username == 'admin'`. This represents a **privilege escalation vulnerability** because:
- The username value comes from decrypted (but unauthenticated) session cookie
- Attackers can forge session cookies containing `username='admin'` using padding oracle attacks
- No additional authorization checks, role-based access control (RBAC), or permission frameworks exist
- Admin privilege grants access to `/flag.txt` file reading operation (line 64)

**4. Flag Disclosure Mechanism (Lines 63-65):**
When a user authenticates with username `'admin'`, the application reads the sensitive flag from filesystem:
```python
if username == 'admin':
    flag = open('/flag.txt').read()
    username = 'Welcome admin! Here is your flag: %s' % flag
```
The flag file (`/flag.txt`) is created during Docker image build (Dockerfile lines 12-13) using an `ARG FLAG` build argument. This build-time secret injection means the flag is permanently embedded in the Docker image layers and visible via `docker history` command.

---

## 3. Authentication & Authorization Deep Dive

### Authentication Mechanisms

**Primary Authentication Method:** Form-based password authentication with custom encrypted session management.

**Complete Authentication Endpoint Inventory:**

| Endpoint | Method | File Location | Line Numbers | Purpose | Authentication Required |
|----------|--------|---------------|--------------|---------|------------------------|
| `/` | GET | `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` | 38-40 | Render login form | No (Public) |
| `/login` | POST | `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` | 42-51 | Process credentials, create session | No (Public) |
| `/welcome` | GET | `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` | 53-71 | Display username/flag | Yes (Session cookie) |

**Authentication Flow Analysis:**

```
[Client] POST /login {username, password}
    ↓
[Line 44-45] Extract form data (no validation, no sanitization)
    username = request.form['username']
    password = request.form['password']
    ↓
[Line 46] Plaintext credential validation
    if username in users and users[username] == password:
    ↓
[Line 48] Encrypt username for session
    encrypted_data = encrypt_data(username)
    ↓
[Line 49] Set session cookie (NO HttpOnly, NO Secure, NO SameSite)
    resp.set_cookie('session', encrypted_data.hex())
    ↓
[Client] Redirect to /welcome with session cookie
```

**Authentication Security Properties (Critical Analysis):**

1. **No Input Validation:** Form data is used directly without length checks, character whitelisting, or format validation. While this doesn't create immediate vulnerabilities due to encryption, it violates defense-in-depth principles.

2. **Plaintext Password Comparison (Line 46):**
```python
if username in users and users[username] == password:
```
**Vulnerability:** No cryptographic hashing (bcrypt, Argon2, PBKDF2)
**Attack Vector:** If source code is leaked or database is compromised (in this case, hardcoded credentials), passwords are immediately exposed
**Recommended Fix:** 
```python
from werkzeug.security import check_password_hash
if username in users and check_password_hash(users[username], password):
```

3. **Hardcoded User Database (Lines 13-15):**
```python
users = {
    "test1": "test1",
    "admin": "somehardpassword"
}
```
**Vulnerability Severity:** CRITICAL
- Credentials committed to version control (git repository searchable)
- No password rotation without code modification
- "somehardpassword" is weak and vulnerable to dictionary attacks
- Test account "test1:test1" provides easy initial access for attackers

4. **No Account Lockout or Rate Limiting:** The `/login` endpoint accepts unlimited authentication attempts with no throttling, CAPTCHA, or account lockout. Attackers can brute-force credentials at wire speed (limited only by network throughput).

5. **No Multi-Factor Authentication (MFA):** Single-factor authentication (password only) provides no defense against credential compromise.

### Session Management and Cookie Security Configuration

**Session Cookie Implementation (Line 49):**
```python
resp.set_cookie('session', encrypted_data.hex())
```

**CRITICAL SECURITY DEFICIENCY - Missing Cookie Security Flags:**

The session cookie is configured with **ZERO security attributes**, creating multiple severe vulnerabilities:

| Flag | Status | Security Impact | Line Reference |
|------|--------|-----------------|----------------|
| **HttpOnly** | ❌ MISSING | Session cookie accessible via JavaScript (`document.cookie`). If XSS vulnerability exists, attacker can steal session cookie and hijack authenticated session. | Line 49 |
| **Secure** | ❌ MISSING | Cookie transmitted over unencrypted HTTP connections. Man-in-the-middle attackers on network can intercept session cookies in plaintext. | Line 49 |
| **SameSite** | ❌ MISSING | Cookie sent with cross-site requests. Enables Cross-Site Request Forgery (CSRF) attacks where attacker tricks authenticated user into executing unwanted actions. | Line 49 |
| **Max-Age / Expires** | ❌ MISSING | Session cookie persists indefinitely until browser close. No server-enforced expiration. Stolen cookies remain valid indefinitely. | Line 49 |
| **Domain** | ❌ MISSING | Cookie sent to all subdomains (if any). Subdomain takeover could lead to session theft. | Line 49 |
| **Path** | ❌ MISSING | Cookie sent to all paths. No path restriction for session scope. | Line 49 |

**Correct Secure Cookie Configuration:**
```python
resp.set_cookie(
    'session', 
    encrypted_data.hex(),
    httponly=True,      # Prevent JavaScript access
    secure=True,        # HTTPS only
    samesite='Strict',  # Prevent CSRF
    max_age=3600,       # 1 hour expiration
    path='/welcome'     # Restrict to protected endpoints
)
```

**Session Cookie Structure and Encryption:**

The session cookie value is a hex-encoded encrypted blob with the following structure:
```
[16 bytes IV][N bytes ciphertext] → hex-encoded → cookie value
```

Example session cookie:
```
session=a1b2c3d4e5f6g7h8i9j0k1l2m3n4o5p6... (hex string)
         └─ First 32 hex chars = 16-byte IV
         └─ Remaining chars = AES-CBC encrypted username
```

**Encryption Key Management (Line 10):**
```python
key = os.urandom(32)
```

**CRITICAL VULNERABILITY - Ephemeral Key:**
- **Problem:** Encryption key regenerated on every application restart using `os.urandom(32)`
- **Impact:** All existing session cookies become undecryptable after server restart, forcing all users to re-authenticate
- **Persistence Issue:** No key storage mechanism (file, environment variable, key vault)
- **Recommended Fix:** Derive key from environment variable or use persistent secret storage:
  ```python
  import os
  from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
  from cryptography.hazmat.primitives import hashes
  
  # Derive key from environment variable
  secret = os.environ.get('SESSION_SECRET_KEY').encode()
  kdf = PBKDF2HMAC(algorithm=hashes.SHA256(), length=32, salt=b'static_salt', iterations=100000)
  key = kdf.derive(secret)
  ```

**Session Validation Process (Lines 54-71):**

```python
@app.route('/welcome')
def welcome():
    encrypted_data = request.cookies.get('session')  # Line 55
    logging.debug(f"encrypted_data: {encrypted_data}")  # Line 56 - LOGS SESSION COOKIE
    
    if encrypted_data:
        try:
            username = decrypt_data(bytes.fromhex(encrypted_data))  # Line 60
            logging.debug(f"decrypted username: {username}")  # Line 61 - LOGS USERNAME
            
            if username == 'admin':
                flag = open('/flag.txt').read()
                username = 'Welcome admin! Here is your flag: %s' % flag
            
            return render_template('welcome.html', username=username)
            
        except Exception as e:
            return str(e)  # Line 70 - ERROR ORACLE
    return redirect(url_for('index'))
```

**Session Validation Vulnerabilities:**

1. **No Session Timeout (Server-Side):** While cookie max-age is unset, there's also no server-side session expiration mechanism. Even if max-age were set, the application doesn't track session creation time or implement sliding expiration.

2. **No Session Fixation Protection:** After successful login, the application does not regenerate the session identifier. Recommended fix:
```python
# After successful authentication
old_session = request.cookies.get('session')
# Generate new session with new random IV
encrypted_data = encrypt_data(username)
# Set new cookie, invalidate old session (requires server-side session store)
```

3. **Exception-Based Padding Oracle (Line 70):** The most critical session vulnerability:
```python
except Exception as e:
    return str(e)
```
This error handler returns raw exception messages to the client, creating a perfect padding oracle. Different exception types reveal cryptographic operation failures:

- `ValueError: non-hexadecimal number found in fromhex()` → Invalid cookie format
- `UnicodeDecodeError: 'utf-8' codec can't decode byte...` → Padding/decryption failure
- Different error messages for padding failures vs. decryption failures

**Padding Oracle Attack Demonstration:**
```
1. Capture valid session cookie: session=abc123def456...
2. Modify last byte of ciphertext: session=abc123def457...
3. Submit to /welcome endpoint
4. Observe error message:
   - "Invalid padding" → padding failure
   - "Cannot decode" → decryption succeeded but invalid UTF-8
5. Repeat for each byte position to decrypt entire session
6. Forge new session with username='admin'
```

### Authorization Model and Privilege Escalation

**Authorization Implementation (Lines 63-65):**
```python
if username == 'admin':
    flag = open('/flag.txt').read()
    username = 'Welcome admin! Here is your flag: %s' % flag
```

**Authorization Model:** Simple string comparison (username == 'admin') with no role-based access control (RBAC), attribute-based access control (ABAC), or permission framework.

**Privilege Escalation Attack Path:**

```
[Attacker] Obtain valid session for 'test1' user
    ↓
[Crypto Attack] Use padding oracle to decrypt session cookie
    ↓ Reveals: username='test1' encrypted with AES-CBC
    ↓
[Session Forgery] Manipulate padding oracle to encrypt username='admin'
    ↓ Create: new session cookie with encrypted 'admin' username
    ↓
[Submit] GET /welcome with forged admin session cookie
    ↓
[Authorization Bypass] Application decrypts to username='admin'
    ↓ Line 63: if username == 'admin' → TRUE
    ↓
[Flag Disclosure] Line 64: flag = open('/flag.txt').read()
    ↓
[Success] Flag rendered in HTML response
```

**Authorization Bypass Scenarios:**

1. **Padding Oracle Privilege Escalation (Primary Attack):**
   - Complexity: Medium (requires ~2000-5000 HTTP requests)
   - Prerequisites: Valid session cookie for any user (including 'test1:test1')
   - Tools: PadBuster, custom Python script, Burp Suite Intruder
   - Success Rate: 100% (deterministic attack)

2. **Bit-Flipping Attack (Alternative):**
   - If usernames 'test1' and 'admin' have similar length, attacker can flip bits in ciphertext to transform 'test1' → 'admin'
   - CBC mode property: `C[i-1] ⊕ P[i] = P'[i]`
   - Requires: (a) known plaintext structure, (b) ability to predict block boundaries
   - Success Rate: 90%+ for short usernames

3. **Debug Mode Code Execution (If Debugger Pin Bypassed):**
   - Flask debug mode (line 74) exposes Werkzeug interactive debugger
   - If PIN is guessed/leaked, attacker gains remote code execution
   - Can directly read `/flag.txt` via Python console
   - Success Rate: 5-10% (requires PIN bypass)

**No Authorization Framework:**
- No middleware enforcing authorization policies
- No decorator-based access control (`@requires_role('admin')`)
- No centralized permission checking
- Authorization logic embedded in business logic (line 63)

**Recommended Authorization Framework:**
```python
from functools import wraps

def requires_role(role):
    def decorator(f):
        @wraps(f)
        def decorated_function(*args, **kwargs):
            username = get_current_user()  # From session
            user_role = get_user_role(username)
            if user_role != role:
                abort(403)
            return f(*args, **kwargs)
        return decorated_function
    return decorator

@app.route('/welcome')
@requires_role('admin')
def welcome():
    # Authorization already enforced by decorator
    flag = open('/flag.txt').read()
    return render_template('welcome.html', flag=flag)
```

### SSO/OAuth/OIDC Flows

**NOT IMPLEMENTED** - The application uses only custom form-based authentication with no third-party identity providers, OAuth 2.0 flows, OpenID Connect integration, or SAML-based single sign-on.

**No OAuth/OIDC Components:**
- No callback endpoints for OAuth redirects
- No `state` parameter validation (CSRF protection for OAuth)
- No `nonce` parameter validation (replay protection for OIDC)
- No JWT token validation
- No JWKS (JSON Web Key Set) fetching
- No OpenID Connect discovery endpoints

If SSO were to be implemented, critical security requirements would include:
1. **State Parameter Validation:** Generate cryptographically random `state` parameter, store in session, validate on callback
2. **Nonce Validation:** Generate random `nonce`, include in ID token claims, validate to prevent replay
3. **Redirect URI Validation:** Strict whitelist of allowed callback URLs to prevent authorization code interception
4. **Token Signature Verification:** Validate JWT signatures using provider's public keys from JWKS endpoint
5. **TLS/SSL Required:** OAuth flows MUST use HTTPS to prevent authorization code/token interception

---

## 4. Data Security & Storage

### Database Security

**Database Type:** In-memory Python dictionary (no persistent database)

**User Credential Storage (Lines 13-15):**
```python
users = {
    "test1": "test1",
    "admin": "somehardpassword"
}
```

**CRITICAL SECURITY DEFICIENCIES:**

1. **No Encryption at Rest:** Credentials stored in plaintext in source code. If application source is compromised (e.g., git repository leak, source code disclosure vulnerability), all user passwords are immediately exposed.

2. **No Password Hashing:** Passwords compared via direct string equality (`users[username] == password` at line 46). Industry best practices mandate cryptographic password hashing:
   - **Recommended:** bcrypt (cost factor 12-14), Argon2id (memory-hard function), PBKDF2-SHA256 (100,000+ iterations)
   - **Current Implementation:** None (plaintext comparison)
   - **Attack Impact:** Rainbow table attacks, credential stuffing, password reuse exploitation

3. **Hardcoded Credentials:** Passwords committed to version control represent a critical supply chain vulnerability:
   - Git history retains all historical password values
   - CI/CD pipelines may log source code contents
   - Developer workstations contain unencrypted credentials
   - Code sharing platforms (GitHub, GitLab) expose credentials if repository is public

4. **No Access Controls:** In-memory dictionary has no access control layer, authentication, or audit logging. Any code with access to the `users` variable can read/modify credentials.

5. **No Data Persistence:** Application restart wipes all user data (though in this case, users are hardcoded, so no runtime data loss occurs). For real applications, this would result in complete data loss.

**Recommended Secure Credential Storage:**
```python
from werkzeug.security import generate_password_hash, check_password_hash

# Password hashing during user creation
users = {
    "test1": generate_password_hash("test1", method='pbkdf2:sha256:150000'),
    "admin": generate_password_hash(os.environ['ADMIN_PASSWORD'], method='pbkdf2:sha256:150000')
}

# Authentication with hash verification
if username in users and check_password_hash(users[username], password):
    # Authentication successful
```

**Database Configuration (Not Applicable):**
- No SQL/NoSQL database
- No connection string handling
- No query parameterization needed (no database queries)
- No database-level encryption
- No row-level security or multi-tenant isolation

### Data Flow Security

**Critical Data Paths:**

**Path 1: Credential Submission (Login Flow)**
```
[Browser] → HTTP POST /login {username, password} → [Flask]
    ↓ (UNENCRYPTED - No HTTPS/TLS)
[Line 44-45] Extract form data
    username = request.form['username']  # Plain text
    password = request.form['password']  # Plain text
    ↓
[Line 46] Plaintext comparison
    if username in users and users[username] == password
    ↓ (NO SANITIZATION)
[Line 48] Encrypt username only (password discarded)
    encrypted_data = encrypt_data(username)
    ↓
[Line 49] Set session cookie
    resp.set_cookie('session', encrypted_data.hex())
    ↓ (UNENCRYPTED - No Secure flag)
[Browser] Stores session cookie
```

**Data Flow Vulnerabilities:**
- **No Input Sanitization:** Form data used directly without validation, length checks, or character filtering
- **No Output Encoding:** While Jinja2 auto-escapes by default, the application doesn't explicitly enforce encoding
- **No TLS/SSL:** Credentials traverse network in plaintext HTTP, vulnerable to passive network sniffing

**Path 2: Session Validation (Protected Resource Access)**
```
[Browser] → HTTP GET /welcome + Cookie: session=<hex> → [Flask]
    ↓ (UNENCRYPTED - No HTTPS)
[Line 55] Extract session cookie
    encrypted_data = request.cookies.get('session')
    ↓
[Line 56] DEBUG LOG: Session cookie logged
    logging.debug(f"encrypted_data: {encrypted_data}")  # SENSITIVE DATA IN LOGS
    ↓
[Line 60] Decrypt session
    username = decrypt_data(bytes.fromhex(encrypted_data))
    ↓
[Lines 28-36] AES-CBC decryption
    iv = encrypted_data[:16]
    ct = encrypted_data[16:]
    cipher = Cipher(algorithms.AES(key), modes.CBC(iv), ...)
    padded_plaintext = decryptor.update(ct) + decryptor.finalize()
    ↓
[Line 33] DEBUG LOG: Decrypted data logged
    logging.debug(f"padded_plaintext: {padded_plaintext}")  # SENSITIVE DATA IN LOGS
    ↓
[Line 35] Strip padding
    plaintext = padded_plaintext.rstrip(b'\x00')
    ↓
[Line 61] DEBUG LOG: Username logged
    logging.debug(f"decrypted username: {username}")  # PII IN LOGS
    ↓
[Line 63] Authorization check
    if username == 'admin':
    ↓
[Line 64] Read sensitive file
    flag = open('/flag.txt').read()
    ↓
[Line 67] Render in template
    render_template('welcome.html', username=username)
    ↓ (UNENCRYPTED - No HTTPS)
[Browser] Display flag in HTML
```

**Data Flow Security Issues:**
1. **Excessive Debug Logging (Lines 56, 61, 33):** Sensitive data (session cookies, usernames, plaintext) logged at DEBUG level, potentially persisted to log files
2. **No Data Validation Pipeline:** Decrypted username used directly without sanitization or validation
3. **Sensitive Data Rendering:** Flag value rendered directly in HTML template without additional access controls
4. **No Encryption in Transit:** All data (credentials, cookies, flags) transmitted over HTTP

### Encryption at Rest and In Transit

**Encryption at Rest:** ❌ NONE

The application stores no persistent data. However, analyzing security posture:

1. **Flag File Storage (`/flag.txt`):**
   - **Location:** Container filesystem root (`/flag.txt`)
   - **Encryption:** None (plaintext file)
   - **Permissions:** World-readable (no file permissions set in Dockerfile)
   - **Recommended:** Encrypt flag with application-specific key, decrypt only when accessed by authorized user

2. **Session Cookies (Client-Side Storage):**
   - **Encryption:** AES-256-CBC (encrypted)
   - **Issues:** No authentication (HMAC), vulnerable to padding oracle and bit-flipping
   - **Recommended:** Use authenticated encryption (AES-GCM) or HMAC-SHA256 signature

3. **Application Source Code:**
   - **Hardcoded Credentials:** Plaintext passwords in `app.py` (lines 13-15)
   - **Recommended:** Move to environment variables, use secret management service (AWS Secrets Manager, HashiCorp Vault)

**Encryption in Transit:** ❌ NONE (CRITICAL VULNERABILITY)

**Application Configuration (Line 74):**
```python
app.run(debug=True, host='0.0.0.0', port=8000)
```

**TLS/SSL Analysis:**
- **Protocol:** HTTP (unencrypted)
- **Port:** 8000 (non-standard, no HTTPS)
- **Certificate:** None configured
- **HSTS Header:** Not present

**Impact of No TLS/SSL:**
1. **Credential Interception:** Login credentials transmitted in plaintext, vulnerable to network sniffing (Wireshark, tcpdump)
2. **Session Hijacking:** Session cookies transmitted without encryption, allowing man-in-the-middle attackers to steal sessions
3. **Flag Disclosure:** Sensitive flag values transmitted in cleartext when admin accesses `/welcome`
4. **No Forward Secrecy:** No ephemeral key exchange, all traffic decryptable if encryption key is compromised

**Recommended TLS Configuration:**
```python
# Use production WSGI server with TLS
# gunicorn with SSL certificates
gunicorn --certfile=cert.pem --keyfile=key.pem --bind 0.0.0.0:443 app:app

# Or configure reverse proxy (nginx) with TLS termination
# nginx.conf:
# server {
#     listen 443 ssl;
#     ssl_certificate /path/to/cert.pem;
#     ssl_certificate_key /path/to/key.pem;
#     ssl_protocols TLSv1.2 TLSv1.3;
#     ssl_ciphers HIGH:!aNULL:!MD5;
#     location / {
#         proxy_pass http://127.0.0.1:8000;
#     }
# }
```

**Security Headers for TLS (CRITICAL - Not Implemented):**

**Strict-Transport-Security (HSTS) Header:**
- **Purpose:** Forces browsers to use HTTPS for all future requests
- **Current Status:** ❌ Not configured
- **Recommended Configuration:**
  ```python
  @app.after_request
  def set_hsts(response):
      response.headers['Strict-Transport-Security'] = 'max-age=31536000; includeSubDomains; preload'
      return response
  ```
- **Location to Implement:** Should be configured in infrastructure (nginx, CDN) or Flask middleware
- **File to Modify:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (add after_request handler)
- **Line to Add After:** Line 74 (before `app.run()`)

**Cache-Control Headers for Sensitive Responses:**
- **Purpose:** Prevent caching of sensitive flag data
- **Current Status:** ❌ Not configured
- **Recommended Configuration:**
  ```python
  @app.route('/welcome')
  def welcome():
      # ... existing code ...
      resp = make_response(render_template('welcome.html', username=username))
      resp.headers['Cache-Control'] = 'no-store, no-cache, must-revalidate, private'
      resp.headers['Pragma'] = 'no-cache'
      resp.headers['Expires'] = '0'
      return resp
  ```
- **Location to Implement:** Within `/welcome` route handler
- **File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py`
- **Lines to Modify:** 53-71 (add headers before return statement)

### Multi-Tenant Data Isolation

**NOT APPLICABLE** - This application is single-tenant with no multi-tenancy architecture. Analysis:

- **No Tenant Concept:** Application does not implement tenant IDs, organization isolation, or customer segmentation
- **No Tenant Context Propagation:** No middleware or request context tracking tenant information
- **No Row-Level Security:** No database with tenant-scoped queries
- **No Schema Isolation:** In-memory dictionary shared across all users

If multi-tenancy were implemented, required security controls would include:
1. **Tenant ID Validation:** Verify tenant ID on every request, prevent tenant ID manipulation
2. **Database Query Scoping:** Add `WHERE tenant_id = ?` to all queries
3. **Session Tenant Binding:** Include tenant ID in encrypted session, validate on decryption
4. **Cross-Tenant Data Access Prevention:** Implement authorization checks preventing tenant A from accessing tenant B's data
5. **Audit Logging:** Log all cross-tenant access attempts

---

## 5. Attack Surface Analysis

### External Entry Points (Network-Accessible Endpoints)

The application exposes **three primary HTTP endpoints** on port 8000 (Docker container internal) mapped to host port 33029. All endpoints use unencrypted HTTP protocol with no TLS/SSL protection.

**Endpoint 1: Root/Index Page**
- **Route:** `GET /`
- **File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py`
- **Line:** 38-40
- **Handler Function:** `index()`
- **Authentication Required:** No (Public)
- **Purpose:** Render login form HTML template
- **Code Implementation:**
```python
@app.route('/')
def index():
    return render_template('index.html')
```
- **Attack Surface Analysis:**
  - **Input Vectors:** None (static page rendering)
  - **Output Encoding:** Jinja2 autoescape enabled (safe from template injection)
  - **Rate Limiting:** None (unlimited requests)
  - **Security Headers:** None configured
  - **Information Disclosure:** Reveals application framework (Flask) via `Server` header
  - **CSRF Protection:** Not applicable (GET request, no state changes)
- **Template File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/templates/index.html`
- **Template Contents:**
```html
<form action="{{ url_for('login') }}" method="post">
    <input type="text" name="username" placeholder="Username" required>
    <input type="password" name="password" placeholder="Password" required>
    <input type="submit" value="Login">
</form>
```
- **Template Vulnerabilities:**
  - **No CSRF Token:** Form lacks anti-CSRF token, enabling login CSRF attacks
  - **No Input Length Limits:** HTML `maxlength` attribute not set, allows unlimited input
  - **No Client-Side Validation:** No JavaScript validation (server-side validation also absent)

**Endpoint 2: Login Authentication Handler**
- **Route:** `POST /login`
- **File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py`
- **Line:** 42-51
- **Handler Function:** `login()`
- **Authentication Required:** No (Public - this IS the authentication endpoint)
- **Input Parameters:**
  - `username` (form data, type: text)
  - `password` (form data, type: password)
- **Purpose:** Validate credentials, create encrypted session cookie, redirect to welcome page
- **Code Implementation:**
```python
@app.route('/login', methods=['POST'])
def login():
    username = request.form['username']  # Line 44 - No validation
    password = request.form['password']  # Line 45 - No validation
    if username in users and users[username] == password:  # Line 46 - Plaintext comparison
        resp = make_response(redirect(url_for('welcome')))
        encrypted_data = encrypt_data(username)  # Line 48 - AES-CBC encryption
        resp.set_cookie('session', encrypted_data.hex())  # Line 49 - No security flags
        return resp
    return 'Invalid username or password', 403  # Line 51 - Generic error message (good)
```
- **Attack Surface Analysis:**
  - **Input Vectors:** 
    1. `username` field (unrestricted text input)
    2. `password` field (unrestricted password input)
    3. HTTP headers (User-Agent, Referer, etc. - not validated)
  - **Input Validation:** ❌ None (no length limits, character whitelisting, format validation)
  - **Rate Limiting:** ❌ None (allows unlimited brute-force attempts)
  - **Account Lockout:** ❌ None (no temporary/permanent account locking after failed attempts)
  - **Credential Validation:** Plaintext comparison (line 46) - no bcrypt/Argon2
  - **Session Creation:** Custom AES-CBC encryption (vulnerable to padding oracle - see Section 3)
  - **Cookie Security:** Missing HttpOnly, Secure, SameSite flags (CRITICAL - see Section 3)
  - **Error Messages:** Generic "Invalid username or password" (good - doesn't reveal which field is incorrect)
  - **CSRF Protection:** ❌ None (no token validation)
  - **SQL Injection:** Not applicable (no database)
  - **Command Injection:** Not applicable (no system commands)
  - **Information Disclosure:** Timing attacks possible (string comparison leaks username validity)

**Endpoint 3: Protected Welcome Page (Flag Disclosure)**
- **Route:** `GET /welcome`
- **File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py`
- **Line:** 53-71
- **Handler Function:** `welcome()`
- **Authentication Required:** Yes (session cookie with encrypted username)
- **Input Parameters:**
  - `session` (cookie, hex-encoded encrypted data)
- **Purpose:** Display welcome message; disclose flag if authenticated as admin
- **Code Implementation:**
```python
@app.route('/welcome')
def welcome():
    encrypted_data = request.cookies.get('session')  # Line 55
    logging.debug(f"encrypted_data: {encrypted_data}")  # Line 56 - LOGS COOKIE
    
    if encrypted_data:
        try:
            username = decrypt_data(bytes.fromhex(encrypted_data))  # Line 60 - Padding oracle here
            logging.debug(f"decrypted username: {username}")  # Line 61 - LOGS USERNAME
            
            if username == 'admin':  # Line 63 - Authorization check
                flag = open('/flag.txt').read()  # Line 64 - File read
                username = 'Welcome admin! Here is your flag: %s' % flag  # Line 65
            
            return render_template('welcome.html', username=username)  # Line 67
            
        except Exception as e:
            return str(e)  # Line 70 - ERROR ORACLE (CRITICAL VULNERABILITY)
    return redirect(url_for('index'))  # Line 71
```
- **Attack Surface Analysis:**
  - **Input Vectors:**
    1. `session` cookie (hex-encoded ciphertext - PRIMARY ATTACK SURFACE)
    2. HTTP headers (not processed)
  - **Input Validation:** Minimal (hex decoding via `bytes.fromhex()`, but no length/format validation)
  - **Decryption Vulnerabilities:**
    - **Padding Oracle (Line 70):** Exception messages disclose decryption/padding failures
    - **No MAC Validation:** Ciphertext can be manipulated without detection
    - **Custom Padding:** Null byte padding vulnerable to attack
  - **Authorization Logic:**
    - **Single String Comparison (Line 63):** `if username == 'admin'`
    - **No Role-Based Access Control:** No RBAC framework
    - **Privilege Escalation Vector:** Forged session cookie bypasses authorization
  - **File Access (Line 64):**
    - **Path:** Hardcoded `/flag.txt` (no user input in path - no path traversal risk)
    - **Permissions:** Container filesystem read access required (present)
    - **Error Handling:** `open()` errors not caught (would trigger exception disclosure at line 70)
  - **Information Disclosure:**
    - **Debug Logging (Lines 56, 61):** Session cookies and usernames logged to application logs
    - **Exception Messages (Line 70):** Raw Python exceptions returned to client
    - **Timing Attacks:** Decryption timing may leak information about ciphertext validity
  - **Output Encoding:** Jinja2 autoescape protects against XSS in username rendering (Line 67)
  - **XSS Risk:** Low (Jinja2 auto-escapes `{{ username }}` in template)
  - **CSRF Protection:** Not applicable (GET request, no state changes)

**Endpoint 4: Static CSS File**
- **Route:** `GET /static/style.css` (Flask default static route)
- **File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/static/style.css`
- **Authentication Required:** No (Public)
- **Purpose:** Serve CSS styling for login and welcome pages
- **Attack Surface:** Minimal (static file serving, no user input processing)
- **Security Headers:** No `X-Content-Type-Options: nosniff` header (minor MIME sniffing risk)

### Internal Service Communication

**NO INTERNAL SERVICE COMMUNICATION** - This application is a monolithic single-container deployment with no microservices architecture, message queues, service meshes, or inter-process communication.

**Architecture Characteristics:**
- **Single Process:** Flask application runs in a single Python process
- **No Microservices:** No separate authentication service, database service, or API gateway
- **No Message Queues:** No RabbitMQ, Kafka, Redis pub/sub, or async messaging
- **No Service Mesh:** No Istio, Linkerd, or Consul service discovery
- **No RPC:** No gRPC, Thrift, or REST calls to internal services

**Trust Relationships:** Not applicable (no inter-service communication to analyze)

**Security Assumptions:** All code runs in the same security context (same container, same process, same privilege level)

### Input Validation Patterns

**CRITICAL FINDING: NO INPUT VALIDATION IMPLEMENTED**

The application accepts user input from three sources (form fields and cookies) with **zero validation, sanitization, or encoding** prior to processing:

**Input Source 1: Login Form Fields (Lines 44-45)**
```python
username = request.form['username']  # No validation
password = request.form['password']  # No validation
```

**Validation Gaps:**
- ❌ No length limits (username/password can be arbitrarily long)
- ❌ No character whitelisting (accepts any Unicode characters)
- ❌ No format validation (no regex, pattern matching, or structure checks)
- ❌ No encoding normalization (no Unicode normalization - NFC/NFD)
- ❌ No injection prevention (though no SQL/command injection sinks exist)
- ❌ No null byte filtering (username with `\x00` would be truncated by padding removal)

**Recommended Validation:**
```python
import re

def validate_username(username):
    if not username or len(username) > 50:
        raise ValueError("Username must be 1-50 characters")
    if not re.match(r'^[a-zA-Z0-9_-]+$', username):
        raise ValueError("Username must contain only alphanumeric characters, hyphens, and underscores")
    return username

def validate_password(password):
    if not password or len(password) < 8 or len(password) > 128:
        raise ValueError("Password must be 8-128 characters")
    return password

# In login handler:
try:
    username = validate_username(request.form['username'])
    password = validate_password(request.form['password'])
except ValueError as e:
    return str(e), 400
```

**Input Source 2: Session Cookie (Line 55)**
```python
encrypted_data = request.cookies.get('session')
```

**Validation Gaps:**
- ❌ No length validation (cookie can be arbitrarily long)
- ❌ No format validation before `bytes.fromhex()` call (relies on exception handling)
- ❌ No HMAC signature verification (no integrity check)
- ❌ No replay protection (no timestamp or nonce validation)
- ❌ No origin validation (no binding to IP address or User-Agent)

**Hex Decoding Validation (Line 60):**
```python
username = decrypt_data(bytes.fromhex(encrypted_data))
```
- `bytes.fromhex()` throws `ValueError` for invalid hex characters
- Exception caught at line 69 and disclosed at line 70 (information leakage)

**Recommended Cookie Validation:**
```python
def validate_session_cookie(cookie_value):
    # Length check (IV + ciphertext should be 16 + N bytes in hex)
    if not cookie_value or len(cookie_value) < 32 or len(cookie_value) % 2 != 0:
        raise ValueError("Invalid session format")
    
    # Hex validation
    try:
        raw_data = bytes.fromhex(cookie_value)
    except ValueError:
        raise ValueError("Invalid session encoding")
    
    # Length validation (minimum: 16-byte IV + 16-byte block)
    if len(raw_data) < 32:
        raise ValueError("Invalid session length")
    
    # HMAC validation (if implemented)
    # hmac_signature = raw_data[-32:]
    # ciphertext = raw_data[:-32]
    # if not hmac.compare_digest(compute_hmac(ciphertext), hmac_signature):
    #     raise ValueError("Invalid session signature")
    
    return raw_data
```

**Input Source 3: HTTP Headers (Implicit)**
While the application doesn't explicitly process HTTP headers, Flask automatically parses headers like `User-Agent`, `Referer`, `Cookie`, etc. The application doesn't validate or sanitize these values, but they're not used in security-sensitive operations.

**No Output Encoding (Template Rendering):**
- Jinja2's autoescape feature is enabled by default for `.html` files
- Username variable is automatically HTML-escaped when rendered: `{{ username }}`
- However, application doesn't explicitly enforce encoding (relies on framework defaults)

**Template File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/templates/welcome.html:7`
```html
<h1>Welcome, {{ username }}!</h1>
```
- Jinja2 automatically converts `<` to `&lt;`, `>` to `&gt;`, preventing XSS
- If autoescape were disabled or `|safe` filter used, XSS would be possible

### Background Processing (Async Jobs)

**NO BACKGROUND PROCESSING** - This application does not implement asynchronous task processing, job queues, or background workers.

**Architecture Characteristics:**
- **Synchronous Request Processing:** All requests processed in the main Flask thread
- **No Celery/RQ/Huey:** No task queue frameworks
- **No Cron Jobs:** No scheduled tasks
- **No Message Queue Consumers:** No RabbitMQ/Kafka consumers
- **No Webhook Handlers:** No async webhook processing (though `/login` could theoretically trigger async actions, none are implemented)

**Security Implications:**
- No privilege escalation via background job manipulation
- No async job injection vulnerabilities
- No task queue poisoning attacks
- No worker process exploitation

If background processing were added, security concerns would include:
1. **Input Validation:** Validate all task parameters before queuing
2. **Authentication:** Verify task creator identity and authorization
3. **Rate Limiting:** Prevent task queue flooding/DoS
4. **Privilege Context:** Ensure workers run with least-privilege permissions
5. **Secret Handling:** Don't pass secrets in task payloads (use secure parameter passing)

---

## 6. Infrastructure & Operational Security

### Secrets Management

**CRITICAL DEFICIENCY: Hardcoded Secrets and Insecure Secret Handling**

**Secret 1: User Credentials**
- **Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py:13-15`
- **Type:** Hardcoded passwords in source code
- **Content:**
```python
users = {
    "test1": "test1",
    "admin": "somehardpassword"
}
```
- **Severity:** CRITICAL
- **Issues:**
  - Credentials committed to version control (git repository)
  - No secret rotation mechanism (requires code change)
  - Admin password "somehardpassword" is weak and guessable
  - Test account "test1:test1" provides easy initial access
- **Recommended Fix:**
```python
import os
users = {
    "test1": os.environ.get('TEST_USER_PASSWORD'),
    "admin": os.environ.get('ADMIN_PASSWORD')
}
```

**Secret 2: CTF Flag**
- **Location 1 (Environment):** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/.env:1`
```
FLAG="flag{60afd62a-6165-42f9-9b06-e45c453d2902}"
```
- **Location 2 (Dockerfile):** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/Dockerfile:12-13`
```dockerfile
ARG FLAG
RUN echo -n $FLAG > /flag.txt
```
- **Location 3 (Docker Compose):** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/docker-compose.yml:5-6`
```yaml
args:
  - FLAG
```
- **Severity:** HIGH
- **Issues:**
  - `.env` file may be committed to git (check `.gitignore`)
  - Build-time secret injection embeds flag in Docker image layers
  - Flag visible via `docker history <image_id>` command
  - Docker Compose passes environment variable as build arg (logged in build output)
- **Recommended Fix:**
```dockerfile
# Use runtime secrets instead of build args
# docker-compose.yml:
services:
  web:
    secrets:
      - flag_secret
secrets:
  flag_secret:
    file: ./flag.txt
```

**Secret 3: AES Encryption Key**
- **Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py:10`
```python
key = os.urandom(32)
```
- **Severity:** CRITICAL
- **Issues:**
  - Ephemeral key generation (lost on restart)
  - No key persistence (no file storage, environment variable, or key vault)
  - No key rotation mechanism
  - No key derivation from passphrase
  - Vulnerable to memory dump attacks
- **Recommended Fix:**
```python
import os
from cryptography.hazmat.primitives.kdf.pbkdf2 import PBKDF2HMAC
from cryptography.hazmat.primitives import hashes

# Derive key from environment variable
secret_passphrase = os.environ.get('SESSION_SECRET_KEY', 'changeme').encode()
kdf = PBKDF2HMAC(
    algorithm=hashes.SHA256(),
    length=32,
    salt=b'static-salt-change-in-production',
    iterations=100000,
)
key = kdf.derive(secret_passphrase)
```

**Secret Rotation:** ❌ NOT IMPLEMENTED
- No mechanism to rotate encryption keys
- No mechanism to rotate admin password without code changes
- No graceful session invalidation during key rotation

**Recommended Secret Management Solutions:**
1. **Environment Variables (Minimum):**
   - Move secrets to `.env` file (ensure `.gitignore` includes `.env`)
   - Use Docker secrets or Kubernetes secrets for container deployment
   - Inject secrets at runtime, not build time

2. **Secret Management Services (Recommended):**
   - **AWS Secrets Manager:** Centralized secret storage with rotation
   - **HashiCorp Vault:** Dynamic secret generation and access control
   - **Azure Key Vault:** Managed secret and key storage
   - **Google Secret Manager:** Cloud-native secret management

3. **Key Management Services (KMS):**
   - Encrypt encryption keys with master keys from KMS
   - Use envelope encryption for data protection
   - Enable automatic key rotation

### Configuration Security

**Environment Configuration:**

**File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/.env`
```
FLAG="flag{60afd62a-6165-42f9-9b06-e45c453d2902}"
```

**Configuration Issues:**
1. **No Environment Separation:**
   - Single `.env` file for all environments (dev, staging, prod)
   - No differentiation between development and production configurations
   - Debug mode enabled in production (line 74 of `app.py`)

2. **Secrets in Environment Files:**
   - Flag stored in plaintext `.env` file
   - No encryption of environment variables
   - Risk of committing `.env` to version control

3. **No Configuration Validation:**
   - Application doesn't validate required environment variables exist
   - No schema validation for configuration values
   - No type checking for configuration parameters

**Docker Configuration:**

**File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/docker-compose.yml`
```yaml
version: '3'
services:
  web:
    build:
      context: ./app
      args:
        - FLAG
    ports:
      - "8000"
    healthcheck:
      test: ["CMD", "curl", "-f", "http://127.0.0.1:8000/"]
      timeout: 1s
      retries: 5
      interval: 10s
```

**Security Issues:**
- **Build-Time Secrets:** FLAG passed as build argument (embedded in image)
- **No Resource Limits:** No CPU/memory limits configured
- **No Security Options:** No `security_opt`, `cap_drop`, `read_only` settings
- **No User Specification:** Container runs as root (no `user` directive)
- **Random Port Mapping:** Port 8000 mapped to random host port (current: 33029)

**Recommended Secure Configuration:**
```yaml
version: '3.8'
services:
  web:
    build:
      context: ./app
    ports:
      - "127.0.0.1:8000:8000"  # Bind to localhost only
    environment:
      - FLASK_ENV=production
      - SESSION_SECRET_KEY_FILE=/run/secrets/session_key
    secrets:
      - session_key
      - flag_secret
    user: "1000:1000"  # Non-root user
    read_only: true
    tmpfs:
      - /tmp
    cap_drop:
      - ALL
    cap_add:
      - NET_BIND_SERVICE
    security_opt:
      - no-new-privileges:true
    deploy:
      resources:
        limits:
          cpus: '0.5'
          memory: 256M
secrets:
  session_key:
    file: ./secrets/session_key.txt
  flag_secret:
    file: ./secrets/flag.txt
```

**Application Configuration (Flask):**

**File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py:74`
```python
app.run(debug=True, host='0.0.0.0', port=8000)
```

**CRITICAL SECURITY ISSUES:**

1. **Debug Mode Enabled:**
   - `debug=True` enables Werkzeug interactive debugger
   - Exposes stack traces with source code and variable values
   - Allows code execution via debugger PIN (if bypassed)
   - **Recommended:** `debug=False` in production

2. **Listening on All Interfaces:**
   - `host='0.0.0.0'` exposes application on all network interfaces
   - Container is accessible from any network the host is connected to
   - **Recommended:** `host='127.0.0.1'` for localhost-only access, use reverse proxy (nginx) for external access

3. **Development Server in Production:**
   - Werkzeug development server not suitable for production
   - No concurrent request handling
   - No connection pooling or request throttling
   - **Recommended:** Use production WSGI server (Gunicorn, uWSGI, Waitress)

**Recommended Production Configuration:**
```python
import os

if __name__ == '__main__':
    # Development mode
    if os.environ.get('FLASK_ENV') == 'development':
        app.run(debug=True, host='127.0.0.1', port=8000)
    else:
        # Production mode - use gunicorn instead
        # gunicorn --bind 127.0.0.1:8000 --workers 4 app:app
        app.run(debug=False, host='127.0.0.1', port=8000)
```

**Security Header Configuration (Infrastructure):**

**CRITICAL FINDING:** No infrastructure configuration defines security headers like HSTS or Cache-Control.

**Files Checked:**
- ❌ No nginx configuration found
- ❌ No Apache configuration found
- ❌ No CDN configuration found
- ❌ No Kubernetes Ingress configuration found
- ❌ No reverse proxy configuration found

**Application-Level Headers (Missing):**
The Flask application does not configure any security headers in code. Required headers and their locations for implementation:

**Header 1: Strict-Transport-Security (HSTS)**
- **Purpose:** Force HTTPS for all future requests (requires TLS to be configured first)
- **Current Status:** ❌ Not configured anywhere
- **Location to Implement:** Flask `@app.after_request` middleware or reverse proxy
- **File to Modify:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py`
- **Recommended Code:**
```python
@app.after_request
def set_security_headers(response):
    response.headers['Strict-Transport-Security'] = 'max-age=31536000; includeSubDomains; preload'
    return response
```
- **Line to Add After:** Line 37 (before route definitions)

**Header 2: Cache-Control (Sensitive Data Protection)**
- **Purpose:** Prevent browser/proxy caching of sensitive flag data
- **Current Status:** ❌ Not configured
- **Location to Implement:** `/welcome` route handler
- **File to Modify:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py`
- **Recommended Code:**
```python
@app.route('/welcome')
def welcome():
    # ... existing decryption and authorization logic ...
    resp = make_response(render_template('welcome.html', username=username))
    resp.headers['Cache-Control'] = 'no-store, no-cache, must-revalidate, private'
    resp.headers['Pragma'] = 'no-cache'
    resp.headers['Expires'] = '0'
    return resp
```
- **Lines to Modify:** 67 (replace `return render_template(...)` with response object and headers)

**Additional Security Headers (Not Configured):**
- **X-Content-Type-Options:** `nosniff` (prevent MIME sniffing)
- **X-Frame-Options:** `DENY` (prevent clickjacking)
- **Content-Security-Policy:** `default-src 'self'` (XSS protection)
- **X-XSS-Protection:** `1; mode=block` (legacy XSS filter)
- **Referrer-Policy:** `no-referrer` (prevent referrer leakage)

**Recommended Comprehensive Security Header Configuration:**
```python
@app.after_request
def set_security_headers(response):
    response.headers['Strict-Transport-Security'] = 'max-age=31536000; includeSubDomains; preload'
    response.headers['X-Content-Type-Options'] = 'nosniff'
    response.headers['X-Frame-Options'] = 'DENY'
    response.headers['Content-Security-Policy'] = "default-src 'self'; style-src 'self' 'unsafe-inline'"
    response.headers['X-XSS-Protection'] = '1; mode=block'
    response.headers['Referrer-Policy'] = 'no-referrer'
    return response
```

### External Dependencies

**Python Package Dependencies:**

**File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/requirements.txt`
```
Flask==3.0.3
cryptography
```

**Dependency Analysis:**

**1. Flask 3.0.3**
- **Purpose:** Web application framework (routing, request handling, templating)
- **Security Implications:**
  - Well-maintained, actively developed framework
  - Version 3.0.3 released April 2024 (reasonably recent)
  - No known critical CVEs in this version (as of analysis date)
  - **Concern:** Using development server instead of production WSGI server

**2. cryptography (version unspecified in requirements.txt)**
- **Purpose:** Cryptographic primitives (AES encryption, ciphers, algorithms)
- **Installed Version:** 42.0.8 (verified from environment)
- **Security Implications:**
  - Reputable library maintained by Python Cryptographic Authority
  - Version 42.0.8 released 2024 (current)
  - No known CVEs in this version
  - **Concern:** Misuse of low-level primitives (CBC without MAC) creates vulnerabilities despite using secure library

**Transitive Dependencies (Not Listed):**
Flask depends on additional packages:
- **Werkzeug:** WSGI utility library (provides development server, routing, request/response)
- **Jinja2:** Template engine (provides autoescape for XSS protection)
- **itsdangerous:** Cryptographic signing (not used in this application)
- **click:** CLI framework (for Flask CLI commands)
- **MarkupSafe:** HTML escaping library (used by Jinja2)

**Dependency Security Recommendations:**

1. **Pin All Versions:**
```
Flask==3.0.3
cryptography==42.0.8
Werkzeug==3.0.3
Jinja2==3.1.4
```

2. **Vulnerability Scanning:**
```bash
# Use pip-audit to check for known vulnerabilities
pip-audit

# Use safety to check against vulnerability database
safety check --file requirements.txt

# Use Snyk for comprehensive dependency scanning
snyk test --file=requirements.txt
```

3. **Automated Updates:**
- Use Dependabot (GitHub) or Renovate to automatically create PRs for dependency updates
- Configure CI/CD to run security scans on every commit

**System Dependencies (Container):**

**File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/Dockerfile:3-4`
```dockerfile
RUN apt-get update && \
    apt-get install -y iputils-ping curl procps
```

**Installed Packages:**
- **iputils-ping:** Provides `ping` command (network diagnostics)
- **curl:** HTTP client (used for Docker health checks)
- **procps:** Process utilities (`ps`, `top`, `kill`)

**Security Implications:**
- These utilities are not required for application functionality (only for debugging/health checks)
- **curl** is necessary for health check: `curl -f http://127.0.0.1:8000/`
- **ping** and **procps** increase attack surface if container is compromised (post-exploitation utilities)
- **Recommendation:** Remove `iputils-ping` and `procps` from production images, keep only `curl` for health checks

**No External Services:**
This application does not integrate with external services:
- ❌ No third-party APIs (payment processors, analytics, logging services)
- ❌ No external authentication providers (OAuth, SAML, LDAP)
- ❌ No cloud services (AWS S3, Google Cloud Storage, Azure Blob)
- ❌ No CDN (Cloudflare, Fastly, CloudFront)
- ❌ No email services (SendGrid, Mailgun, SES)
- ❌ No monitoring/observability services (Datadog, New Relic, Sentry)

**Security Benefit:** Minimal external attack surface (no third-party API credential exposure, no supply chain risks from external services)

### Monitoring & Logging

**Logging Configuration:**

**File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py:8`
```python
logging.basicConfig(level=logging.DEBUG, format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')
```

**Logging Analysis:**

**1. Log Level: DEBUG**
- **Issue:** DEBUG level enabled in production
- **Security Impact:** Logs sensitive data (see below)
- **Recommendation:** Set to `INFO` or `WARNING` in production

**2. Sensitive Data Logged:**

**Line 33 (Decryption Function):**
```python
logging.debug(f"padded_plaintext: {padded_plaintext}")
```
- **Logged Data:** Decrypted username with padding bytes
- **Severity:** CRITICAL (PII disclosure, session plaintext exposure)

**Line 56 (Welcome Route):**
```python
logging.debug(f"encrypted_data: {encrypted_data}")
```
- **Logged Data:** Session cookie (hex-encoded ciphertext)
- **Severity:** HIGH (session hijacking if logs compromised)

**Line 61 (Welcome Route):**
```python
logging.debug(f"decrypted username: {username}")
```
- **Logged Data:** Username (PII)
- **Severity:** MEDIUM (PII disclosure)

**Security Event Logging Gaps:**

**Missing Security Events:**
- ❌ Failed login attempts (no logging at line 51)
- ❌ Successful logins (no logging at line 48)
- ❌ Admin access to flag (no logging at line 64)
- ❌ Session decryption failures (exception logged, but not as security event)
- ❌ Unusual request patterns (no rate limit logging)
- ❌ Authentication anomalies (no detection/logging)

**Recommended Security Audit Logging:**
```python
import logging

# Configure separate security audit logger
security_logger = logging.getLogger('security_audit')
security_handler = logging.FileHandler('/var/log/app/security_audit.log')
security_handler.setFormatter(logging.Formatter('%(asctime)s - %(levelname)s - %(message)s'))
security_logger.addHandler(security_handler)
security_logger.setLevel(logging.INFO)

# Log authentication attempts
@app.route('/login', methods=['POST'])
def login():
    username = request.form['username']
    password = request.form['password']
    
    if username in users and users[username] == password:
        security_logger.info(f"Login successful: username={username}, ip={request.remote_addr}")
        # ... create session ...
    else:
        security_logger.warning(f"Login failed: username={username}, ip={request.remote_addr}")
        return 'Invalid username or password', 403

# Log admin flag access
@app.route('/welcome')
def welcome():
    # ... decryption logic ...
    if username == 'admin':
        security_logger.info(f"Admin flag access: username={username}, ip={request.remote_addr}")
        flag = open('/flag.txt').read()
        # ... render flag ...
```

**Log Storage and Retention:**
- **Current:** Logs output to stdout/stderr (captured by Docker: `docker logs xben-103-24_web_1`)
- **Issue:** No persistent log storage (logs lost when container is removed)
- **Issue:** No log rotation (container logs grow indefinitely)
- **Issue:** No centralized logging (logs not aggregated)

**Recommended Log Management:**
1. **Centralized Logging:**
   - Use ELK Stack (Elasticsearch, Logstash, Kibana)
   - Use Splunk for enterprise log aggregation
   - Use AWS CloudWatch Logs for cloud deployments
   - Use Grafana Loki for Kubernetes environments

2. **Log Rotation:**
   - Configure Docker log rotation in daemon.json:
```json
{
  "log-driver": "json-file",
  "log-opts": {
    "max-size": "10m",
    "max-file": "3"
  }
}
```

3. **Secure Log Storage:**
   - Encrypt logs at rest
   - Restrict access to logs (RBAC)
   - Implement log integrity verification (immutable logs)
   - Retain logs for compliance period (GDPR: 90 days minimum)

**Monitoring:** ❌ NOT IMPLEMENTED
- No application performance monitoring (APM)
- No security event monitoring (SIEM)
- No anomaly detection
- No alerting on security events

**Docker Health Check:**
**File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/docker-compose.yml:9-13`
```yaml
healthcheck:
  test: ["CMD", "curl", "-f", "http://127.0.0.1:8000/"]
  timeout: 1s
  retries: 5
  interval: 10s
```
- **Purpose:** Verify application is responsive (HTTP 200 from root endpoint)
- **Security Note:** Health check hits public endpoint `/`, doesn't verify authentication/authorization functionality
- **Recommendation:** Create dedicated `/health` endpoint that checks critical services (in this simple app, not necessary)

---

## 7. Overall Codebase Indexing

The XBEN-103-24 codebase is a **compact, deliberately vulnerable Flask web application** designed as a CTF (Capture The Flag) security challenge with a total of approximately **250 lines of code across 10 files**. The repository follows a typical Docker-based Python application structure with clear separation between application code, infrastructure configuration, and environment variables, making it straightforward to navigate for security analysis but also revealing how simplicity can mask critical cryptographic vulnerabilities.

**Directory Structure and Organization:**

```
/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/
├── .env                          # Environment variables (FLAG secret)
├── Makefile                      # Build automation (references ../common.mk)
├── benchmark.json                # CTF challenge metadata
├── docker-compose.yml           # Container orchestration configuration
└── app/                         # Application directory (all code in this folder)
    ├── Dockerfile               # Container build instructions
    ├── requirements.txt         # Python dependencies (Flask, cryptography)
    ├── start.sh                 # Unused startup script (SSH + Flask)
    ├── app.py                   # Main Flask application (76 lines - ALL LOGIC HERE)
    ├── static/
    │   └── style.css           # CSS styling for web pages
    └── templates/
        ├── index.html          # Login form template
        └── welcome.html        # Authenticated user page template
```

**Key Organizational Characteristics:**

1. **Monolithic Application Design:** All application logic is contained in a single 76-line Python file (`app/app.py`), with no modular decomposition, separate controllers, models, services, or utility libraries. This consolidation makes the code easy to read for educational purposes but violates production software engineering principles of separation of concerns and modularity.

2. **Infrastructure-as-Code Separation:** Build and deployment configurations are cleanly separated from application code:
   - **Container Build:** `app/Dockerfile` defines the Python 3.8 runtime environment, system dependencies, and flag injection mechanism
   - **Orchestration:** `docker-compose.yml` manages service configuration, port mapping, and health checks
   - **Build Automation:** `Makefile` provides convenience commands for building/running (references parent directory's `common.mk`, suggesting this is part of a larger CTF challenge suite)

3. **Template-Based Frontend:** Uses Flask's default Jinja2 templating with a traditional server-side rendering architecture (no JavaScript frameworks, no API-first design). Templates are minimal (each ~20 lines) with basic HTML structure and form handling.

4. **Environment Configuration:** Follows twelve-factor app methodology with externalized configuration (`.env` file), though implementation is flawed (secrets in environment files, no environment separation).

**Security-Relevant Structural Findings:**

**Single Point of Analysis (`app.py`):** Since all authentication, authorization, encryption, and session management logic exists in one 76-line file, security reviewers can quickly identify vulnerabilities by reading this single file. This is both an advantage (easy to audit) and a risk (no defense-in-depth through modular security controls). The file structure is:

```python
Lines 1-9:     Imports and logging configuration
Lines 10-11:   Global state (encryption key, user database)
Lines 13-16:   Hardcoded user credentials
Lines 18-25:   Encryption function (AES-CBC with null byte padding)
Lines 27-36:   Decryption function (padding oracle vulnerability)
Lines 38-40:   Route: GET / (login page)
Lines 42-51:   Route: POST /login (authentication)
Lines 53-71:   Route: GET /welcome (flag disclosure)
Lines 73-74:   Application runner (debug mode enabled)
```

**No Testing Infrastructure:** The repository contains no test files, unit tests, integration tests, or security test suites. Common testing directories that are absent include:
- ❌ No `tests/` directory
- ❌ No `test_*.py` files
- ❌ No pytest configuration
- ❌ No test fixtures or mocks
- ❌ No CI/CD testing pipeline

This absence suggests the application is intended solely as a challenge target, not a production codebase, but also means there's no automated verification of security controls or regression testing for vulnerability fixes.

**Build and Deployment Tooling:**

**Dockerfile Structure:** The container build process follows a standard multi-step pattern:
1. Base image selection (`python:3.8-slim`)
2. System dependency installation (curl, ping, procps)
3. Python dependency installation (Flask, cryptography)
4. Application code copy
5. **Secret injection:** Flag written to filesystem via build ARG (security anti-pattern)
6. Entrypoint configuration (Python interpreter runs `app.py`)

**Security Impact:** The Dockerfile embeds secrets at **build time** rather than **runtime**, meaning the flag is permanently baked into the Docker image layers and visible via `docker history`. This is a common mistake in containerized application development.

**Docker Compose Configuration:** Minimal service definition with:
- **Build context:** `./app` directory
- **Port exposure:** Random host port mapping to container port 8000
- **Health check:** HTTP GET to root endpoint every 10 seconds
- **No security hardening:** No user specification (runs as root), no resource limits, no security options

**Makefile Integration:** References `../common.mk`, indicating this challenge is part of a suite sharing common build targets. This parent Makefile likely defines targets like `make build`, `make run`, `make clean`, providing consistent interfaces across multiple challenges.

**Code Generation and Conventions:**

**No Code Generation:** The application uses no code generation tools, ORMs with auto-generated models, or API scaffolding frameworks. All code is hand-written.

**Python Conventions:**
- **PEP 8 Compliance:** Code generally follows Python style guidelines (4-space indentation, snake_case naming)
- **Type Hints:** ❌ Not used (no function type annotations)
- **Docstrings:** ❌ Not present (no function documentation)
- **Error Handling:** Basic try-except blocks (lines 57-70) but with security-critical error disclosure

**Flask Conventions:**
- **Application Factory Pattern:** ❌ Not used (global `app` object instead of factory function)
- **Blueprints:** ❌ Not used (all routes in single file)
- **Configuration Objects:** ❌ Not used (configuration hardcoded)
- **Extension Initialization:** Minimal (no Flask-Login, Flask-WTF, Flask-SQLAlchemy)

**Discoverability of Security Components:**

**High Discoverability:** The flat, single-file structure makes security components extremely easy to locate:
- **Authentication Logic:** Lines 42-51 (`/login` route)
- **Session Management:** Lines 18-36 (encrypt_data/decrypt_data functions), Line 49 (set_cookie)
- **Authorization Logic:** Line 63 (`if username == 'admin'`)
- **Cryptographic Functions:** Lines 18-36 (AES-CBC implementation)
- **Secret Storage:** Lines 13-15 (user credentials), Line 10 (encryption key)
- **Flag Access:** Line 64 (`open('/flag.txt').read()`)

**Risk Assessment:** The simplicity creates a **false sense of security** where developers might assume "it's so simple, what could go wrong?" but critical vulnerabilities are embedded in the 76 lines of code. The lack of security libraries (no Flask-Login, no password hashing, no CSRF protection) means all security must be manually implemented, increasing vulnerability risk.

**Version Control and Supply Chain Considerations:**

**Git Repository Risks:**
- **Hardcoded Secrets:** If committed to git, credentials (lines 13-15) are permanently in history
- **Flag Exposure:** `.env` file may be in git history if not gitignored from start
- **No `.gitignore`:** Not present in listing (should ignore `.env`, `*.pyc`, `__pycache__/`)

**Dependency Management:**
- **Unpinned Versions:** `requirements.txt` has `cryptography` without version pin (should be `cryptography==42.0.8`)
- **No Dependency Lock:** No `requirements.lock` or `Pipfile.lock` for reproducible builds
- **No Vulnerability Scanning:** No evidence of `pip-audit` or `safety` usage

**Challenge Metadata:**

**File:** `benchmark.json` (not shown in file contents but listed in directory)
- Likely contains CTF challenge description, points value, category, and hints
- May reveal intended vulnerability (padding oracle attack)
- Security teams should review this file to understand challenge scope and intended solution path

**Overall Architecture Impact on Security:**

The codebase's **minimal complexity** is a **double-edged sword** from a security perspective:

**Advantages for Security Analysis:**
- ✅ Small attack surface (only 3 routes, no complex business logic)
- ✅ Easy to audit (entire application in 76 lines)
- ✅ No hidden complexity (no ORM magic, no middleware chains, no framework abstractions)
- ✅ Clear vulnerability demonstration (educational value for learning padding oracle attacks)

**Disadvantages for Security:**
- ❌ No defense-in-depth (single file means single point of failure)
- ❌ No security libraries (all security manually implemented with flaws)
- ❌ No input validation framework (all validation manually implemented - but isn't)
- ❌ No security testing (no tests means no regression detection)
- ❌ Custom cryptography (reimplementation of standard session management creates vulnerabilities)

**Conclusion:** This codebase exemplifies how **architectural simplicity does not equal security**. Despite being "just 76 lines of code," it contains multiple CRITICAL-severity vulnerabilities including padding oracle attacks, missing cookie security flags, hardcoded credentials, and debug mode in production. The flat structure makes vulnerabilities discoverable for security researchers but provides no organizational security benefits for defenders.

---

## 8. Critical File Paths

The following file paths are referenced throughout the security analysis and represent critical components requiring manual review during penetration testing:

### Configuration
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/.env` - Environment variables containing FLAG secret
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/Dockerfile` - Container build instructions with flag injection mechanism (lines 12-13)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/docker-compose.yml` - Service orchestration with build arguments and health checks

### Authentication & Authorization
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 13-15) - Hardcoded user credentials
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 42-51) - POST /login authentication endpoint
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 63-65) - Admin authorization check and flag disclosure
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (line 49) - Session cookie configuration (missing security flags)

### API & Routing
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 38-40) - GET / route (login page)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 53-71) - GET /welcome route (protected resource)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/templates/index.html` - Login form template
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/templates/welcome.html` - Welcome page template with username rendering

### Data Models & DB Interaction
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 13-15) - In-memory user database (plaintext passwords)
- No persistent database files (in-memory only)

### Dependency Manifests
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/requirements.txt` - Python dependencies (Flask==3.0.3, cryptography)

### Sensitive Data & Secrets Handling
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (line 10) - AES encryption key generation (ephemeral)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 18-25) - encrypt_data() function (AES-CBC with null byte padding)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 27-36) - decrypt_data() function (padding oracle vulnerability)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (line 64) - Flag file read operation
- `/flag.txt` (container filesystem) - CTF flag storage location

### Middleware & Input Validation
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 44-45) - Form input extraction (no validation)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (line 55) - Cookie input extraction
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (line 60) - Hex decoding and decryption (error oracle)
- No input validation middleware files (not implemented)

### Logging & Monitoring
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (line 8) - Logging configuration (DEBUG level)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (lines 33, 56, 61) - Debug logging of sensitive data
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (line 70) - Exception disclosure to client

### Infrastructure & Deployment
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/Makefile` - Build automation
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/start.sh` - Startup script (unused)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py` (line 74) - Application runner (debug=True, host='0.0.0.0')
- No nginx, Kubernetes, or infrastructure configuration files

### CTF Flag Storage
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/.env` (line 1) - FLAG environment variable
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/Dockerfile` (lines 12-13) - Flag written to /flag.txt during build
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/docker-compose.yml` (line 6) - FLAG build argument
- `/flag.txt` (inside container) - Runtime flag file location

---

## 9. XSS Sinks and Render Contexts

**EXECUTIVE FINDING:** No directly exploitable XSS sinks were identified in the network-accessible application code. The Flask application uses Jinja2 templating with default autoescape enabled, which provides baseline protection against Cross-Site Scripting attacks. However, **one dangerous coding pattern** was identified that could become an XSS vulnerability under specific conditions.

### Dangerous Pattern: Exception Message Reflection (Not Currently Exploitable)

**Sink Type:** Reflected Exception Messages in HTML Context

**File Path:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py`

**Line Number:** 70

**Render Context:** HTML Body (Flask default Content-Type: text/html; charset=utf-8)

**Code Snippet:**
```python
@app.route('/welcome')
def welcome():
    encrypted_data = request.cookies.get('session')
    if encrypted_data:
        try:
            username = decrypt_data(bytes.fromhex(encrypted_data))
            if username == 'admin':
                flag = open('/flag.txt').read()
                username = 'Welcome admin! Here is your flag: %s' % flag
            return render_template('welcome.html', username=username)
        except Exception as e:
            return str(e)  # LINE 70 - DANGEROUS PATTERN
    return redirect(url_for('index'))
```

**User Input Source:** `session` cookie (encrypted session data containing username)

**Why This Is Potentially Dangerous:**

Flask's default behavior for `return str(...)` is to return a response with `Content-Type: text/html; charset=utf-8`, meaning the browser interprets the response as HTML. If an exception message contained user-controlled HTML or JavaScript, it would be rendered and executed in the browser context. The pattern `return str(e)` outputs raw exception messages directly to the client without HTML escaping.

**Why It's Not Currently Exploitable:**

The exception messages generated by the current code path do **not** reflect user input in a way that allows HTML/JavaScript injection:

1. **`bytes.fromhex()` Exceptions:**
   - Exception: `ValueError: non-hexadecimal number found in fromhex() arg at position X`
   - User input is not directly included in message (only position number)
   - Not exploitable for XSS

2. **AES Decryption Exceptions:**
   - Various cryptography library exceptions from decryption failures
   - Exception messages are standardized library messages
   - Do not include user-controlled plaintext/ciphertext in message body
   - Not exploitable for XSS

3. **`decode()` Exceptions:**
   - Exception: `UnicodeDecodeError: 'utf-8' codec can't decode byte 0xXX in position Y`
   - Includes byte value and position, not user-controlled string
   - Not exploitable for XSS

4. **`open('/flag.txt')` Exceptions:**
   - File path is hardcoded (`/flag.txt`), not user-controlled
   - Exception would be `FileNotFoundError: [Errno 2] No such file or directory: '/flag.txt'`
   - Not exploitable for XSS

**Hypothetical Exploitation Scenario (Future Risk):**

If the code were modified to include user input in exception messages, XSS would become possible:

```python
# HYPOTHETICAL VULNERABLE CODE (NOT PRESENT IN CURRENT APPLICATION)
try:
    username = decrypt_data(bytes.fromhex(encrypted_data))
    if len(username) > 50:
        raise ValueError(f"Username too long: {username}")  # Would reflect username
except Exception as e:
    return str(e)  # Would output: "Username too long: <script>alert('XSS')</script>"
```

**Security Recommendation:**

Replace the exception disclosure with proper error handling:

```python
except Exception as e:
    logging.error(f"Session validation error: {type(e).__name__} - {str(e)}")
    return "Invalid session", 400
```

### Safe Implementation: Jinja2 Template Rendering

**File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/templates/welcome.html`

**Line:** 7

**Render Context:** HTML Body (Inside `<h1>` tag)

**Code Snippet:**
```html
<h1>Welcome, {{ username }}!</h1>
```

**XSS Protection Status:** ✅ SAFE

**Why It's Safe:**

Flask enables Jinja2's autoescape feature by default for all `.html` template files. When rendering `{{ username }}`, Jinja2 automatically HTML-escapes dangerous characters:

| Input Character | Escaped Output |
|----------------|----------------|
| `<` | `&lt;` |
| `>` | `&gt;` |
| `&` | `&amp;` |
| `"` | `&quot;` |
| `'` | `&#39;` |

**Example XSS Payload Neutralization:**

If a user somehow managed to inject the username `<script>alert('XSS')</script>` (e.g., via padding oracle attack to forge session cookie), the rendered HTML would be:

```html
<h1>Welcome, &lt;script&gt;alert('XSS')&lt;/script&gt;!</h1>
```

The browser would display the literal text `<script>alert('XSS')</script>` instead of executing JavaScript.

**Autoescape Verification:**

Flask's autoescape is enabled by default in the Jinja2 environment initialization. The application does not disable autoescape or use the `|safe` filter, maintaining XSS protection.

**Potential XSS Bypass Scenarios (Not Present):**

The following scenarios would create XSS vulnerabilities, but **none are present in this application**:

1. **Manual Autoescape Disable:**
```python
# NOT PRESENT - Would be vulnerable
app.jinja_env.autoescape = False
```

2. **Using |safe Filter:**
```html
<!-- NOT PRESENT - Would be vulnerable -->
<h1>Welcome, {{ username|safe }}!</h1>
```

3. **Using Markup() Object:**
```python
# NOT PRESENT - Would be vulnerable
from markups import Markup
return render_template('welcome.html', username=Markup(username))
```

4. **Rendering in JavaScript Context:**
```html
<!-- NOT PRESENT - Would be vulnerable -->
<script>
var username = "{{ username }}";  // Would need JavaScript escaping, not HTML escaping
</script>
```

### No Other XSS Sinks Identified

**Comprehensive Search Results:**

The following XSS sink patterns were searched for and **not found** in the codebase:

**HTML Body Context Sinks:**
- ❌ `innerHTML` - Not present (no JavaScript files in application)
- ❌ `outerHTML` - Not present
- ❌ `document.write()` - Not present
- ❌ `document.writeln()` - Not present
- ❌ `insertAdjacentHTML()` - Not present
- ❌ `Range.createContextualFragment()` - Not present
- ❌ jQuery sinks (`.html()`, `.append()`, `.after()`, etc.) - Not present (jQuery not used)

**JavaScript Context Sinks:**
- ❌ `eval()` - Not present in application code
- ❌ `Function()` constructor - Not present
- ❌ `setTimeout(string)` - Not present
- ❌ `setInterval(string)` - Not present
- ❌ Direct `<script>` tag injection - Not present

**Template Injection Sinks:**
- ❌ `render_template_string()` - Not used (only `render_template()` with safe static templates)
- ❌ Unsafe Jinja2 filters (`|safe`, `Markup()`) - Not present
- ❌ Autoescape disable - Not present

**HTML Attribute Context Sinks:**
- ❌ Event handlers (`onclick`, `onerror`, `onload`, etc.) - Not present in templates
- ❌ URL attributes with user input (`href=`, `src=`) - Not present
- ❌ `style` attribute injection - Not present

**No SQL Injection (Database Not Used):**
- Application uses in-memory dictionary, no database queries
- No SQL injection sinks present

**No Command Injection:**
- No `os.system()`, `subprocess`, `eval()`, `exec()` calls in application code
- No command execution sinks present

### Summary: XSS Attack Surface

**Current XSS Risk:** **LOW**

The application's XSS attack surface is minimal due to:
1. ✅ Jinja2 autoescape enabled by default
2. ✅ No JavaScript files or DOM manipulation code
3. ✅ No unsafe template filters or manual escaping disablement
4. ✅ Minimal template complexity (only 2 templates, ~40 lines total)
5. ✅ No dynamic HTML generation via JavaScript

**Identified Risks:**
1. ⚠️ Exception message disclosure (line 70) - dangerous pattern but not currently exploitable
2. ⚠️ No Content-Security-Policy header - would provide defense-in-depth against XSS
3. ⚠️ No X-XSS-Protection header - legacy browser XSS filter not enabled

**Recommendations:**
1. **Fix exception handling (Priority: HIGH):**
```python
except Exception as e:
    logging.error(f"Session error: {type(e).__name__}")
    return "Invalid session", 400
```

2. **Add Content-Security-Policy header (Priority: MEDIUM):**
```python
@app.after_request
def set_csp(response):
    response.headers['Content-Security-Policy'] = "default-src 'self'; style-src 'self' 'unsafe-inline'"
    return response
```

3. **Maintain autoescape (Priority: CRITICAL):**
   - Never disable Jinja2 autoescape
   - Never use `|safe` filter on user input
   - Always use `render_template()`, never `render_template_string()` with user input

---

## 10. SSRF Sinks

**EXECUTIVE FINDING:** **NO SSRF (Server-Side Request Forgery) SINKS FOUND IN NETWORK-ACCESSIBLE CODE**

After comprehensive analysis of the entire codebase, including all network-accessible endpoints, imported libraries, and request handling logic, **zero SSRF vulnerabilities** were identified. The application does not make any outbound HTTP/HTTPS requests, open network sockets to external hosts, or perform any operations that could be exploited for Server-Side Request Forgery attacks.

### Analysis Methodology

**Comprehensive Search Coverage:**

**1. HTTP Client Libraries (Not Found):**
- ❌ Python `requests` library - Not imported, not in requirements.txt
- ❌ `urllib`, `urllib2`, `urllib3` - Not imported
- ❌ `httplib`, `http.client` - Not imported
- ❌ `aiohttp` (async HTTP) - Not imported
- ❌ Third-party HTTP clients (`httpx`, `treq`) - Not present

**2. Socket Operations (Not Found):**
- ❌ `socket.connect()` - Not used
- ❌ Raw socket creation (`socket.socket()`) - Not used
- ❌ `telnetlib`, `ftplib`, `smtplib` - Not imported

**3. URL Openers & File Includes (Not Found):**
- ❌ `urllib.urlopen()` - Not used
- ❌ `urllib.request.urlretrieve()` - Not used
- ❌ `open()` with URLs - Only used with hardcoded local path (`/flag.txt`)
- ❌ `requests.get()` - Not available (requests not imported)

**4. Subprocess & External Commands (Not Found):**
- ❌ `subprocess.call()`, `subprocess.run()`, `subprocess.Popen()` - Not used
- ❌ `os.system()` - Not used
- ❌ `os.popen()` - Not used
- ❌ `exec()`, `eval()` - Not used for network requests

**5. Redirect Handlers (Analyzed - Safe):**
The application uses `redirect()` in two locations, but both use hardcoded internal routes:

**Location 1:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py:47`
```python
resp = make_response(redirect(url_for('welcome')))
```
- **Analysis:** `url_for('welcome')` generates internal route `/welcome`
- **User Input:** None (route name is hardcoded string `'welcome'`)
- **SSRF Risk:** None (internal redirect only)

**Location 2:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py:71`
```python
return redirect(url_for('index'))
```
- **Analysis:** `url_for('index')` generates internal route `/`
- **User Input:** None (route name is hardcoded string `'index'`)
- **SSRF Risk:** None (internal redirect only)

**6. File Operations (Analyzed - Local Only):**

**Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-103-24/app/app.py:64`
```python
flag = open('/flag.txt').read()
```
- **Analysis:** Opens local file with hardcoded path `/flag.txt`
- **User Input:** None (path is hardcoded constant)
- **SSRF Risk:** None (local file read, not URL-based)
- **Path Traversal Risk:** None (no user input in path)

**7. External Service Integrations (Not Present):**
- ❌ No webhook handlers
- ❌ No callback verification endpoints
- ❌ No link preview/unfurl functionality
- ❌ No OAuth/OIDC JWKS fetchers
- ❌ No image processors with URL input
- ❌ No headless browsers (Puppeteer, Playwright, Selenium)
- ❌ No RSS/Atom feed readers
- ❌ No "import from URL" functionality

### Application Architecture: Inbound-Only

**Network Communication Pattern:**

The Flask application operates as a **purely inbound HTTP server** with the following characteristics:

1. **Receives HTTP Requests:** Application listens on port 8000 and accepts incoming HTTP requests
2. **Processes Locally:** All request processing happens within the Python process (decryption, authentication, authorization)
3. **No Outbound Requests:** Application never initiates HTTP/HTTPS requests to external or internal services
4. **Local File I/O Only:** Only filesystem operation is reading `/flag.txt` (local, hardcoded path)
5. **No Database Connections:** No network connections to databases (uses in-memory dictionary)

**Dependency Analysis:**

**Python Package Dependencies:**
```
Flask==3.0.3
cryptography
```

**Flask Transitive Dependencies:**
- `Werkzeug` - WSGI utilities (no HTTP client functionality)
- `Jinja2` - Template engine (no network functionality)
- `itsdangerous` - Cryptographic signing (no network functionality)
- `click` - CLI framework (no network functionality)

**Cryptography Library:**
- Used only for AES encryption/decryption (symmetric cryptography)
- No HTTP client, no URL fetching, no external connections

**System Dependencies (Dockerfile):**
- `curl` - Used only for Docker health checks (not accessible from application code)
- `iputils-ping` - Network diagnostics (not used by application)
- `procps` - Process utilities (not used by application)

**Health Check (Docker Only):**
```yaml
healthcheck:
  test: ["CMD", "curl", "-f", "http://127.0.0.1:8000/"]
```
- `curl` executed by Docker daemon, not application code
- Application code has no access to `curl` command
- Not an SSRF sink (infrastructure-level health check)

### User Input Analysis: No URL Parameters

**All User Input Sources:**

1. **Form Fields (POST /login):**
   - `username` - Used for dictionary lookup and encryption
   - `password` - Used for plaintext comparison
   - **Not used for:** Network requests, URL construction, file paths

2. **Session Cookie (GET /welcome):**
   - `session` - Hex-encoded encrypted username
   - **Not used for:** Network requests, URL construction, file paths

3. **HTTP Headers:**
   - Application doesn't process custom headers
   - Standard headers (User-Agent, Referer) not used for any operations
   - **Not used for:** Network requests, URL construction

**No User-Controlled URLs:**
- No form fields accepting URLs
- No API parameters for webhooks, callbacks, or external resources
- No "next" or "return_url" parameters in redirects
- No file upload functionality that could include URLs

### SSRF Attack Surface: Zero

**Attack Surface Summary:**

| SSRF Sink Category | Count | Status |
|-------------------|-------|--------|
| HTTP/HTTPS Clients | 0 | Not present |
| Raw Socket Connections | 0 | Not present |
| URL Openers | 0 | Not present |
| Redirect to User URL | 0 | Safe (internal redirects only) |
| File Includes with URLs | 0 | Not present |
| Webhook Handlers | 0 | Not present |
| Link Preview/Unfurlers | 0 | Not present |
| OAuth/OIDC JWKS Fetchers | 0 | Not present |
| Image Processors | 0 | Not present |
| Headless Browsers | 0 | Not present |
| **Total SSRF Sinks** | **0** | **None identified** |

### Security Benefit: Minimal External Attack Surface

**Positive Security Finding:**

The complete absence of outbound network requests provides significant security benefits:

1. **No SSRF Vulnerabilities:** Impossible to exploit server to make requests to internal/external resources
2. **No Blind SSRF:** No timing-based or DNS-based SSRF attacks possible
3. **No Cloud Metadata Exploitation:** Cannot access AWS/GCP/Azure instance metadata endpoints
4. **No Internal Network Scanning:** Cannot use server as proxy to scan internal network
5. **No Localhost Service Exploitation:** Cannot attack services listening on localhost (Redis, databases, admin panels)

**Attack Surface Limitation:**

This application's security vulnerabilities lie in other domains:
- ✅ **Cryptographic weaknesses** (padding oracle, no MAC) - Primary attack vector
- ✅ **Authentication flaws** (hardcoded credentials, no password hashing)
- ✅ **Session management** (missing cookie flags, ephemeral keys)
- ❌ **SSRF** - Not applicable (no outbound requests)

### Recommendations

**1. Maintain Inbound-Only Architecture (If Intentional):**

If the application is designed to operate without external dependencies, maintain this security posture:
- ✅ Continue avoiding HTTP client libraries
- ✅ Don't add webhook or callback functionality
- ✅ Don't implement "import from URL" features
- ✅ Don't add link preview or metadata fetching

**2. If Outbound Requests Are Added (Future Development):**

If future requirements necessitate outbound requests, implement SSRF protections:

```python
# Example: Safe HTTP client with SSRF protections
import requests
from urllib.parse import urlparse

ALLOWED_SCHEMES = ['http', 'https']
BLOCKED_IPS = ['127.0.0.1', '169.254.169.254', '::1']  # Localhost and cloud metadata
ALLOWED_DOMAINS = ['example.com', 'api.trusted-service.com']

def safe_fetch_url(url, timeout=5):
    # Parse and validate URL
    parsed = urlparse(url)
    
    # Scheme validation
    if parsed.scheme not in ALLOWED_SCHEMES:
        raise ValueError(f"Scheme not allowed: {parsed.scheme}")
    
    # Domain whitelist
    if parsed.hostname not in ALLOWED_DOMAINS:
        raise ValueError(f"Domain not allowed: {parsed.hostname}")
    
    # IP blocklist (prevent localhost/metadata access)
    if parsed.hostname in BLOCKED_IPS:
        raise ValueError(f"IP blocked: {parsed.hostname}")
    
    # Make request with timeout
    response = requests.get(url, timeout=timeout, allow_redirects=False)
    
    return response.text
```

**3. Defense-in-Depth for Future SSRF Protection:**

- **Network Segmentation:** Run application in isolated network segment with egress filtering
- **Firewall Rules:** Block outbound connections to internal IP ranges (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16)
- **DNS Filtering:** Use DNS resolver that blocks private IP resolution
- **URL Validation:** Whitelist allowed domains, block IP addresses, validate URL scheme
- **Timeout Configuration:** Set aggressive timeouts for any external requests

### Conclusion

**SSRF Risk Assessment: NONE**

This Flask application exhibits **zero SSRF attack surface** due to its inbound-only architecture. The application does not import HTTP client libraries, does not make outbound network requests, and does not process user-controlled URLs. All redirect operations use internal routes, and the single file read operation uses a hardcoded local path.

**Primary Security Concerns:** Cryptographic vulnerabilities (padding oracle), authentication weaknesses, and session management flaws represent the critical attack vectors for this application, not SSRF.

## Authenticated Scans

### SCHEMATHESIS
Status: skipped
Schemas directory not found

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Report generated at: 2025-10-30T03:44:49.614Z