# Pre-Reconnaissance Report

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

## Network Scanning (nmap)
Status: success
Starting Nmap 7.97 ( https://nmap.org ) at 2025-10-24 11:57 -0700
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000025s latency).
Other addresses for localhost (not scanned): ::1
Not shown: 996 closed tcp ports (conn-refused)
PORT      STATE SERVICE   VERSION
80/tcp    open  http      Caddy httpd
|_http-server-header: Caddy
|_http-title: Site doesn't have a title.
443/tcp   open  ssl/https
|_http-title: Site doesn't have a title.
631/tcp   open  ipp       CUPS 2.3
|_http-server-header: CUPS/2.3 IPP/2.1
|_http-title: Home - CUPS 2.3.4
| http-robots.txt: 1 disallowed entry 
|_/
49158/tcp open  http      Golang net/http server
| fingerprint-strings: 
|   FourOhFourRequest: 
|     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: Fri, 24 Oct 2025 18:58:15 GMT
|     Content-Length: 14
|     auth required
|   GenericLines, Help, RTSPRequest, SSLSessionReq: 
|     HTTP/1.1 400 Bad Request
|     Content-Type: text/plain; charset=utf-8
|     Connection: close
|     Request
|   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: Fri, 24 Oct 2025 18:58:00 GMT
|     Content-Length: 14
|_    auth required
| http-auth: 
| HTTP/1.1 401 Unauthorized\x0D
|_  Server returned status 401 but no WWW-Authenticate header.
|_http-title: Site doesn't have a title (text/plain; charset=utf-8).
1 service unrecognized despite returning data. If you know the service/version, please submit the following fingerprint at https://nmap.org/cgi-bin/submit.cgi?new-service :
SF-Port49158-TCP:V=7.97%I=7%D=10/24%Time=68FBCC38%P=arm-apple-darwin24.4.0
SF:%r(GenericLines,67,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nContent-Type:
SF:\x20text/plain;\x20charset=utf-8\r\nConnection:\x20close\r\n\r\n400\x20
SF:Bad\x20Request")%r(GetRequest,192,"HTTP/1\.0\x20401\x20Unauthorized\r\n
SF:Content-Security-Policy:\x20default-src\x20'none';\x20frame-ancestors\x
SF:20'none';\x20script-src\x20'none';\x20script-src-elem\x20'none';\x20scr
SF:ipt-src-attr\x20'none'\r\nContent-Type:\x20text/plain;\x20charset=utf-8
SF:\r\nTailscale-Cap:\x20115\r\nTailscale-Version:\x201\.82\.5-tdec88625e-
SF:gec2eb9730\r\nX-Content-Type-Options:\x20nosniff\r\nX-Frame-Options:\x2
SF:0DENY\r\nDate:\x20Fri,\x2024\x20Oct\x202025\x2018:58:00\x20GMT\r\nConte
SF:nt-Length:\x2014\r\n\r\nauth\x20required\n")%r(HTTPOptions,192,"HTTP/1\
SF:.0\x20401\x20Unauthorized\r\nContent-Security-Policy:\x20default-src\x2
SF:0'none';\x20frame-ancestors\x20'none';\x20script-src\x20'none';\x20scri
SF:pt-src-elem\x20'none';\x20script-src-attr\x20'none'\r\nContent-Type:\x2
SF:0text/plain;\x20charset=utf-8\r\nTailscale-Cap:\x20115\r\nTailscale-Ver
SF:sion:\x201\.82\.5-tdec88625e-gec2eb9730\r\nX-Content-Type-Options:\x20n
SF:osniff\r\nX-Frame-Options:\x20DENY\r\nDate:\x20Fri,\x2024\x20Oct\x20202
SF:5\x2018:58:00\x20GMT\r\nContent-Length:\x2014\r\n\r\nauth\x20required\n
SF:")%r(RTSPRequest,67,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nContent-Type
SF::\x20text/plain;\x20charset=utf-8\r\nConnection:\x20close\r\n\r\n400\x2
SF:0Bad\x20Request")%r(Help,67,"HTTP/1\.1\x20400\x20Bad\x20Request\r\nCont
SF:ent-Type:\x20text/plain;\x20charset=utf-8\r\nConnection:\x20close\r\n\r
SF:\n400\x20Bad\x20Request")%r(SSLSessionReq,67,"HTTP/1\.1\x20400\x20Bad\x
SF:20Request\r\nContent-Type:\x20text/plain;\x20charset=utf-8\r\nConnectio
SF:n:\x20close\r\n\r\n400\x20Bad\x20Request")%r(FourOhFourRequest,192,"HTT
SF:P/1\.0\x20401\x20Unauthorized\r\nContent-Security-Policy:\x20default-sr
SF:c\x20'none';\x20frame-ancestors\x20'none';\x20script-src\x20'none';\x20
SF:script-src-elem\x20'none';\x20script-src-attr\x20'none'\r\nContent-Type
SF::\x20text/plain;\x20charset=utf-8\r\nTailscale-Cap:\x20115\r\nTailscale
SF:-Version:\x201\.82\.5-tdec88625e-gec2eb9730\r\nX-Content-Type-Options:\
SF:x20nosniff\r\nX-Frame-Options:\x20DENY\r\nDate:\x20Fri,\x2024\x20Oct\x2
SF:02025\x2018:58:15\x20GMT\r\nContent-Length:\x2014\r\n\r\nauth\x20requir
SF:ed\n");

Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 26.48 seconds


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


## Technology Detection (whatweb)
Status: success
[1m[34mhttp://localhost:46849[0m [200 OK] [1mBootstrap[0m, [1mHTML5[0m, [1mHTTPServer[0m[[1m[36muvicorn[0m], [1mIP[0m[[0m[22m::1[0m], [1mScript[0m, [1mTitle[0m[[1m[33mPickle CTF[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 reported meet the "In-Scope" criteria defined below.

### 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
- 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

### 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. This includes tools that must be run via:
- A command-line interface (e.g., `go run ./cmd/...`, `python scripts/...`)
- A development environment's internal tooling (e.g., a "run script" button in an IDE)
- CI/CD pipeline scripts or build tools (e.g., Dagger build definitions)
- Database migration scripts, backup tools, or maintenance utilities
- Local development servers, test harnesses, or debugging utilities
- Static files or scripts that require manual opening in a browser (not served by the application)

---

## 1. Executive Summary

This security analysis examines **XBEN-036-24 "Green Pickle"**, a deliberately vulnerable CTF (Capture The Flag) challenge application built with FastAPI. The application presents a **CRITICAL security posture** characterized by complete absence of authentication, authorization, and input validation mechanisms. The primary vulnerability is an **insecure deserialization flaw** via Python's pickle module that enables trivial Remote Code Execution (RCE).

The application exposes three network-accessible endpoints on port 80, all publicly accessible without any authentication requirements. The attack surface is minimal but highly vulnerable: a file upload handler directly deserializes user-provided pickle files without validation, allowing arbitrary code execution. Additional critical weaknesses include plain-text storage of secrets in environment files and Docker build arguments, complete lack of security middleware (CORS, CSRF, rate limiting), and direct exposure of sensitive flag data through public endpoints. While the application demonstrates good XSS protection through Jinja2's default auto-escaping, this is overshadowed by the RCE vulnerability that provides complete system compromise. No SSRF sinks were identified, and no database integration exists—the application relies entirely on file-based storage with inadequate access controls.

The intentionally vulnerable nature of this CTF challenge makes it an effective educational tool for demonstrating insecure deserialization attacks. However, from a penetration testing perspective, the lack of defensive security controls creates an environment where exploitation is trivial and post-exploitation activities would face minimal resistance. The application architecture represents a "worst-case scenario" baseline for security assessment, serving as a clear example of what production applications must avoid.

---

## 2. Architecture & Technology Stack

### Framework & Language

The application is built on **FastAPI 0.116.0** (released 2024), a modern Python ASGI web framework known for its automatic API documentation and Pydantic-based request validation. The runtime environment uses **Python 3.9.24**, which is currently in security-only maintenance phase (ending October 2025). FastAPI runs on **Uvicorn 0.35.0** (ASGI server) wrapped by **Gunicorn 23.0.0** (process manager), providing the HTTP server stack exposed on port 80. The application uses **Jinja2 3.1.6** for HTML templating, which includes auto-escaping by default for HTML contexts—one of the few security features present in the stack.

The technology stack is containerized using **Docker** with the official `tiangolo/uvicorn-gunicorn-fastapi:python3.9` base image (Debian GNU/Linux 13 "Trixie", approximately 1.19 GB). Additional dependencies are minimal: only **lxml 5.2.2** (XML/HTML processing library) is installed beyond base requirements. The large base image size increases the attack surface compared to minimal alternatives like Alpine or distroless images. No security-focused libraries are included—no authentication frameworks, no input validation libraries beyond FastAPI's built-in Pydantic support, and critically, no safeguards against the dangerous use of Python's pickle module.

From a security implications perspective, while FastAPI 0.116.0 is a recent version with good security features including automatic request validation via Pydantic and built-in protection against common web vulnerabilities, **none of these protections help against deserialization attacks**. The framework's OpenAPI documentation auto-generation feature (typically exposed at `/docs`, `/redoc`, and `/openapi.json`) would reveal the API structure to attackers, though these endpoints were not explicitly configured in the code analyzed. The choice to run in a Docker container provides some isolation benefits, but the container runs with default privileges (no USER directive to drop root) and lacks security hardening such as read-only filesystem, capability dropping, or security profiles (AppArmor, seccomp).

### Architectural Pattern

This is a **monolithic web application** with no microservices, no service mesh, and no distributed components. The architecture follows a simple request-response cycle: Client → Port 80 → Uvicorn/Gunicorn → FastAPI Application → Pickle Deserialization / File System Access. The application is completely stateless with no session storage, no database connections, and no external service integrations. All data persistence relies on two text files (`flag.txt` and `decoy.txt`) stored in the container's filesystem.

**Trust boundaries** are virtually non-existent in this architecture. The **external trust boundary** begins at HTTP port 80 exposed via Docker, where all three endpoints (`GET /`, `POST /`, `GET /ping`) are publicly accessible without any authentication gates. There is no network-level filtering, no Web Application Firewall (WAF), and no API gateway sitting in front of the application. User-supplied data flows directly from HTTP requests into dangerous functions (pickle.loads()) without any intermediate validation or sanitization layer. The **internal trust boundary** is equally problematic: the application has direct filesystem access to sensitive flag files with no access control mechanisms, no file integrity monitoring, and no principle of least privilege enforcement.

The **critical security failure** in this architecture is the complete absence of defense-in-depth. A single vulnerability (insecure deserialization) provides immediate Remote Code Execution with no additional barriers. There are no security layers protecting the application: no authentication to bypass, no authorization to escalate, no input validation to evade, and no monitoring to detect malicious activity. The Docker container provides minimal isolation but runs as root by default, potentially enabling container escape via post-exploitation techniques. The application's design philosophy appears to intentionally demonstrate how a lack of security architecture creates catastrophic risk—appropriate for a CTF challenge but representative of what production systems must never resemble.

### Critical Security Components

**Authentication & Authorization: COMPLETELY ABSENT.** The application implements zero authentication mechanisms. There are no login endpoints, no session cookies, no JWT tokens, no OAuth/OIDC integrations, no API keys, and no multi-factor authentication. Every endpoint is publicly accessible to anonymous users. The codebase contains no imports for security dependencies (`OAuth2PasswordBearer`, `HTTPBearer`, `Security`, `Depends` for permission checking), no authentication decorators on route handlers, and no user context management. This represents a complete failure of the CIA triad's availability and confidentiality principles—anyone on the internet can access and manipulate the application.

**Session Management: NOT IMPLEMENTED.** No session storage mechanism exists—no cookies, no JWT tokens, no server-side sessions, no Redis/Memcached integration. The application is entirely stateless, which eliminates session-based attack vectors (session fixation, session hijacking) but also means there's no way to track or limit user actions. The absence of session management makes it impossible to implement security controls like rate limiting per user, account lockout, or suspicious activity detection. While statelessness can be a security benefit in well-designed APIs, here it simply reflects the complete lack of user management infrastructure.

**Input Validation: CRITICALLY INSUFFICIENT.** The POST endpoint at `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/main.py:28-30` accepts arbitrary file uploads via the `pickle_file` parameter without any validation:

```python
if pickle_file:
    print('Loading pickle file')
    pickle.loads(await pickle_file.read())
```

This code performs **direct deserialization of untrusted user input** using Python's pickle module—a well-documented anti-pattern explicitly warned against in Python's official documentation. There is no file type validation (MIME type checking, magic byte inspection), no file size limits, no filename sanitization, and no content inspection. The application will happily deserialize any binary data provided, executing arbitrary Python code embedded in malicious pickle files. This vulnerability is **CWE-502 (Deserialization of Untrusted Data)** and represents a **CVSS 9.8 Critical** severity RCE vector.

**Security Middleware: ABSENT.** Analysis of the application initialization in `main.py` reveals no security middleware configured. There is no CORS (Cross-Origin Resource Sharing) configuration, making the application accept requests from any origin. No CSRF (Cross-Site Request Forgery) protection exists—the file upload form in `index.html` (lines 30-36) contains no CSRF tokens, allowing attackers to trick authenticated users into uploading malicious files through cross-site form submissions. No rate limiting middleware is present, enabling unlimited file upload attempts for brute force or denial-of-service attacks. No security headers are configured—responses lack Content-Security-Policy (CSP), X-Frame-Options, X-Content-Type-Options, Strict-Transport-Security (HSTS), Referrer-Policy, and Permissions-Policy headers. The Dockerfile (`app/Dockerfile:12`) shows uvicorn runs with default settings, confirming no security headers are configured at the server level.

---

## 3. Authentication & Authorization Deep Dive

### Complete Absence of Authentication Infrastructure

The XBEN-036-24 application implements **zero authentication mechanisms**, representing a complete security failure for any production system. Analysis of the main application file (`/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/main.py`, lines 1-44) reveals only three endpoint definitions: `GET /` (home page display), `POST /` (pickle file upload handler), and `GET /ping` (health check). Not a single endpoint includes authentication decorators, dependency injection for user context, or any form of identity verification. The codebase contains no imports of authentication libraries—no `OAuth2PasswordBearer` from `fastapi.security`, no JWT handling libraries like `python-jose` or `pyjwt`, no session management frameworks, and no SSO integration packages. This is not an oversight or incomplete implementation; it is a deliberate architectural decision consistent with the application's purpose as a CTF challenge.

**Authentication API Endpoints: NONE EXIST.** There are no login endpoints (`/login`, `/auth/token`, `/api/authenticate`), no logout functionality, no user registration endpoints, no password reset mechanisms, no token refresh endpoints, and no account management interfaces. An attacker analyzing this application would immediately recognize that the traditional penetration testing approach of credential stuffing, brute force attacks, or authentication bypass techniques is entirely unnecessary—the application simply has no authentication layer to attack or bypass. This fundamentally changes the attack surface analysis: instead of needing to find authentication vulnerabilities, an attacker has direct access to all application functionality from the moment they discover the application's URL.

**Security Implications for Penetration Testing:** From an external attacker perspective, the absence of authentication eliminates an entire phase of the typical attack methodology. There is no need to enumerate users, discover authentication endpoints, test for SQL injection in login forms, attempt credential brute forcing, or search for authentication bypass vulnerabilities. The application's most critical vulnerability (insecure deserialization at `POST /`) is immediately accessible to anonymous attackers without any authentication ceremony. This represents the worst-case security posture: a critical RCE vulnerability with no authentication gate protecting it. In a real-world penetration test, this would be classified as a **Critical finding with maximum ease of exploitation**—the attacker goes directly from reconnaissance to Remote Code Execution in a single HTTP POST request.

### Session Management: Non-Existent

**Session Cookie Configuration: NOT APPLICABLE.** No session cookies are generated or consumed by the application. Analysis of the Jinja2 template responses and FastAPI route handlers confirms that no `Set-Cookie` headers are sent in responses. This means there is no opportunity to assess session cookie security flags (`HttpOnly`, `Secure`, `SameSite`)—these security controls simply don't exist in the application. The application does not import or use `SessionMiddleware` from `starlette.middleware.sessions`, does not configure cookie-based authentication, and performs no cookie operations whatsoever.

**Token Security: NOT IMPLEMENTED.** No JWT (JSON Web Token) handling, no OAuth access tokens, no refresh tokens, and no API key management exists in the codebase. The application does not import JWT libraries (`python-jose`, `pyjwt`, `authlib`), does not define token generation functions, and does not validate bearer tokens in request headers. The stateless design means each HTTP request is processed independently with no concept of user sessions, token expiration, or authentication state. While statelessness can be a security advantage in well-designed APIs (eliminating server-side session storage vulnerabilities), here it simply reflects the complete absence of user management infrastructure.

**Session Invalidation: NOT APPLICABLE.** With no sessions or tokens, there is no session invalidation logic, no logout functionality that destroys authentication state, no token revocation mechanisms, and no session timeout enforcement. Users cannot be forcibly logged out, suspicious sessions cannot be terminated, and there's no way to respond to account compromise by invalidating authentication credentials—because no such credentials exist in the first place.

### Authorization Model: Complete Absence of Access Controls

**RBAC (Role-Based Access Control): NOT IMPLEMENTED.** The application has no concept of user roles such as "admin," "user," or "guest." All three network-accessible endpoints are available to all requesters with identical permissions. There are no role checks in route handlers, no `Depends()` decorators for permission validation, no role assignment logic, and no administrative interfaces requiring elevated privileges. An external attacker has the exact same level of access as a hypothetical authenticated user would have—complete and unrestricted access to all functionality.

**Permission Checking: NOT IMPLEMENTED.** No authorization decorators, no permission validators, no access control lists (ACLs), and no attribute-based access control (ABAC) logic exists in the codebase. The POST endpoint that accepts pickle file uploads (`main.py:23-37`) performs no checks to verify whether the requester should be allowed to upload files, deserialize data, or access sensitive flag information. The GET endpoint that displays flags (`main.py:13-20`) performs no authorization checks before returning sensitive data. Any requester, from any IP address, at any time, can access all application functionality without restriction.

**Multi-Tenancy Security: NOT APPLICABLE.** This is a single-tenant application with no concept of user isolation, no tenant separation mechanisms, and no risk of data leakage between tenants because there are no tenants. The application serves the same data and functionality to all requesters identically.

### SSO/OAuth/OIDC Flows: Not Present

**OAuth/OIDC Integration: NONE.** No OAuth 2.0 flows, no OpenID Connect discovery endpoints, no SSO (Single Sign-On) provider integrations, and no federated authentication mechanisms exist. The application does not implement OAuth callback endpoints (typically `/auth/callback` or `/oauth2/callback`), does not validate OAuth `state` parameters to prevent CSRF attacks in authentication flows, does not validate OpenID Connect `nonce` parameters to prevent replay attacks, and does not fetch or validate JWT tokens from external identity providers.

**Security Assessment:** While the absence of OAuth/OIDC means there are no OAuth-specific vulnerabilities to exploit (authorization code interception, redirect URI manipulation, insufficient state validation), this is not a security strength—it simply reflects that the application has no authentication whatsoever. In a real-world penetration test, the complete absence of authentication would be reported as a **Critical severity finding** that enables all other vulnerabilities to be exploited trivially. For this CTF challenge, the lack of authentication is intentional, ensuring that solving the challenge focuses on exploiting the insecure deserialization vulnerability rather than bypassing authentication barriers.

---

## 4. Data Security & Storage

### Database Security: Not Applicable

**No Database Integration Detected.** Comprehensive analysis of the application codebase, including dependency manifests (Dockerfile at `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/Dockerfile`) and all Python source files, confirms the complete absence of database systems. No database connection strings or credentials were found in environment files, no SQL queries (raw or parameterized) exist in the code, and no Object-Relational Mapping (ORM) frameworks such as SQLAlchemy, Django ORM, or Tortoise-ORM are imported or configured. The application does not interact with PostgreSQL, MySQL, MongoDB, Redis, or any other database technology. All data persistence relies exclusively on two text files stored in the container's filesystem: `flag.txt` (containing the actual CTF flag) and `decoy.txt` (containing a fake flag).

From a **security assessment perspective**, the absence of a database eliminates entire vulnerability classes: SQL injection, NoSQL injection, database credential compromise, connection string exposure, insecure direct object reference (IDOR) through database queries, and mass assignment vulnerabilities through ORM exploitation. However, this does not improve the application's security posture—it simply narrows the attack surface to file-based vulnerabilities. The lack of a database means there is no query parameterization to protect against injection, no database-level access controls to enforce authorization, and no audit logging of data access for security monitoring. The application's reliance on filesystem-based storage with inadequate access controls creates a different but equally serious set of security risks.

### Data Flow Security: Critical Vulnerabilities in File Handling

**Insecure File Access Patterns (CRITICAL).** The application reads sensitive flag data from the filesystem in both GET and POST endpoint handlers (`main.py:15-18` and `main.py:32-35`):

```python
if os.path.exists('decoy.txt'):
    flag = open('decoy.txt').read()
else:
    flag = open('flag.txt').read()
```

This code exhibits multiple security weaknesses. First, **files are opened without context managers** (no `with open(...)` statement), meaning file handles are not explicitly closed, creating potential resource leaks if exceptions occur. Second, **no error handling** exists for file operations—if the files are missing, corrupted, or inaccessible due to permission issues, the application will crash with an unhandled exception, potentially creating denial-of-service conditions and information disclosure through error messages. Third, the **conditional logic creates a critical manipulation opportunity**: if an attacker can delete or move `decoy.txt`, the application will automatically read and expose `flag.txt` instead. This logic flaw is the intended solution path for the CTF challenge—exploiting the pickle deserialization vulnerability to execute `os.remove('decoy.txt')`, causing subsequent requests to reveal the real flag.

**Sensitive Data Exposure (CRITICAL).** The flag value is directly exposed in HTTP responses without any access controls. Both the GET and POST handlers at `/` render the flag into the HTML template (`templates/index.html:14`):

```html
<h5>The current flag is: {{ flag }} </h5>
```

This means **any network-accessible HTTP GET request to the root path** (`http://<target>/`) returns the flag value (either decoy or real, depending on filesystem state) in plain HTML. There is no authentication requirement, no authorization check, no rate limiting to prevent automated flag harvesting, and no anti-automation measures like CAPTCHA. From a penetration testing perspective, this represents complete **information disclosure** of the target sensitive data. The only barrier to capturing the real flag is manipulating the filesystem to remove `decoy.txt`, which the insecure deserialization vulnerability enables trivially.

**Plaintext Secret Storage (CRITICAL).** Sensitive data is stored without encryption in multiple locations. The actual CTF flag exists in plaintext in `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/.env`:

```
FLAG="flag{f96e0e03-a965-4c0d-a9dd-dccb9dfcb22c}"
```

This `.env` file is read during Docker build to inject the flag into `flag.txt` via a `sed` command in `Dockerfile:10`: `RUN sed -i s/FLAG/$FLAG/g flag.txt`. This pattern has severe security implications. **Docker build arguments (ARG) are not secure for secrets**—they are persisted in image metadata and can be extracted using `docker history <image>`. Anyone with access to the Docker image can retrieve the flag without even running the container. Additionally, if the `.env` file is committed to version control (git), the secret becomes permanently embedded in repository history, remaining accessible even if later deleted. The application demonstrates no secret rotation mechanisms, no encryption of sensitive data at rest, and no integration with secret management systems like HashiCorp Vault, AWS Secrets Manager, or Azure Key Vault.

### Multi-Tenant Data Isolation: Not Applicable

The application is single-tenant with no user authentication, no concept of multiple users or organizations, and therefore no multi-tenancy architecture. There are no tenant separation mechanisms, no query filters to isolate data between tenants, no risk of cross-tenant data leakage, and no tenant-specific access controls. All requesters receive identical access to the same data regardless of origin, making tenant isolation analysis irrelevant for this application.

---

## 5. Attack Surface Analysis

### External Entry Points: Network-Accessible HTTP Endpoints

The application exposes **three network-accessible HTTP endpoints** on port 80, all confirmed to be in-scope based on their network reachability in a deployed Docker container environment. These endpoints are defined in `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/main.py` and represent the complete external attack surface of the application.

**Endpoint 1: GET / (Root Path - Home Page Display)**
- **File Location:** `main.py:13-20`
- **HTTP Method:** GET
- **Route:** `/`
- **Authentication:** None (Public Access)
- **Request Parameters:** None
- **Response Format:** HTML (renders `templates/index.html`)
- **Functionality:** Checks if `decoy.txt` exists in filesystem; if yes, reads and displays its contents; if no, reads and displays `flag.txt` contents
- **Security Implications:** This endpoint exposes sensitive flag data to any unauthenticated requester. The conditional logic (`if os.path.exists('decoy.txt')`) creates a state-dependent behavior that attackers can manipulate by altering filesystem state through the insecure deserialization vulnerability in the POST endpoint. Once `decoy.txt` is removed, all GET requests to this endpoint will return the real flag value embedded in the HTML response. The endpoint has no rate limiting, enabling unlimited automated requests to harvest flag data.
- **Attack Vector Relevance:** This endpoint is the **flag exfiltration point** in the CTF challenge attack chain. After exploiting the POST endpoint to delete `decoy.txt`, attackers retrieve the real flag by simply requesting GET / and parsing the HTML response.

**Endpoint 2: POST / (Root Path - Pickle File Upload Handler) [CRITICAL VULNERABILITY]**
- **File Location:** `main.py:23-37`
- **HTTP Method:** POST
- **Route:** `/`
- **Authentication:** None (Public Access)
- **Request Parameters:** `pickle_file` (multipart/form-data file upload, optional)
- **Request Body Structure:** Content-Type: `multipart/form-data`, Field name: `pickle_file`, File type: Any (no validation)
- **Response Format:** HTML (renders `templates/index.html` with current flag value)
- **Functionality:** If a file is uploaded via the `pickle_file` parameter, the endpoint reads the file contents and deserializes it using `pickle.loads(await pickle_file.read())` at line 30. After deserialization (which may execute arbitrary code), the endpoint performs the same flag file reading logic as the GET endpoint and returns the HTML template with the flag value.
- **Security Implications (CRITICAL):** This endpoint contains a **CWE-502 Insecure Deserialization** vulnerability with **CVSS 9.8 Critical** severity. The direct use of `pickle.loads()` on user-supplied file data enables **Remote Code Execution (RCE)** without any validation, sandboxing, or signature verification. Python's pickle module can execute arbitrary code during deserialization via the `__reduce__` magic method. An attacker can craft a malicious pickle file that executes any Python code with the privileges of the application process (typically the web server user, potentially root in this container). No file type validation exists (no MIME type checks, no magic byte inspection), no file size limits are enforced (enabling potential denial-of-service via large uploads), and no CSRF protection prevents cross-site exploitation. The endpoint accepts uploads from any origin (no CORS restrictions) and has no rate limiting to prevent automated exploitation attempts.
- **Attack Vector Relevance:** This is the **primary exploitation endpoint** for the CTF challenge. The intended solution is to upload a malicious pickle file containing code to execute `os.remove('decoy.txt')`, which manipulates the filesystem state such that subsequent requests to GET / return the real flag instead of the decoy. Beyond the CTF scope, this vulnerability enables complete system compromise, data exfiltration, persistence establishment, and lateral movement within the network.

**Endpoint 3: GET /ping (Health Check)**
- **File Location:** `main.py:40-42`
- **HTTP Method:** GET
- **Route:** `/ping`
- **Authentication:** None (Public Access)
- **Request Parameters:** None
- **Response Format:** JSON `{"ping": "pong"}`
- **Functionality:** Returns a static JSON response confirming the application is running
- **Security Implications:** This endpoint is a standard health check used by Docker (docker-compose.yml healthcheck configuration: `curl -f http://localhost/ping`). It presents minimal security risk as it returns no sensitive data, performs no dangerous operations, and has no user-controlled inputs. The endpoint is appropriately public for monitoring purposes. However, its existence does confirm to attackers that the application is live and responsive.
- **Attack Vector Relevance:** Low direct relevance, primarily useful for reconnaissance to confirm service availability.

### API Schema Files

**No API Schema Files Found.** Comprehensive searches for OpenAPI/Swagger definitions (`*.json`, `*.yaml`, `*.yml` with "openapi" or "swagger" content), GraphQL schemas (`*.graphql`, `*.gql`), and JSON Schema files (`*.schema.json`) returned no results. The repository contains no explicit API documentation files that would provide attackers with detailed endpoint specifications, request/response schemas, or authentication requirements.

**Note on FastAPI Auto-Generated Documentation:** While no schema files exist in the repository, FastAPI automatically generates OpenAPI documentation at runtime. In default configurations, these would be accessible at `/docs` (Swagger UI), `/redoc` (ReDoc alternative UI), and `/openapi.json` (raw OpenAPI JSON spec). The code analysis did not find explicit configuration disabling these endpoints, so they may be accessible in a deployed environment. These auto-generated documentation endpoints would reveal the exact API structure including endpoint paths, HTTP methods, request parameter schemas, and response formats. For penetration testing purposes, these documentation endpoints should be checked during reconnaissance to understand the full API surface area.

### Internal Service Communication: Not Applicable

This is a monolithic single-container application with no internal service-to-service communication. There are no microservices, no message queues, no internal API calls between services, and no service mesh architecture. The application does not make outbound HTTP requests to other services, does not consume external APIs, and has no inter-process communication beyond the single FastAPI application process handling HTTP requests. Therefore, there are no internal trust boundaries to analyze, no service-to-service authentication mechanisms to assess, and no internal API security controls to evaluate.

### Input Validation Patterns: Critically Insufficient

**File Upload Validation: NONE.** The POST / endpoint accepts arbitrary file uploads with zero validation. The FastAPI parameter definition `pickle_file: UploadFile = File(None)` provides no validation constraints—no file type restrictions, no size limits, no filename sanitization. The code immediately deserializes uploaded content using `pickle.loads(await pickle_file.read())` without inspecting file headers, MIME types, or content structure. This represents a **complete failure of secure coding practices** for handling untrusted user input.

**Filesystem Operation Validation: NONE.** The application performs filesystem operations (`os.path.exists()`, `open().read()`) without path validation, directory traversal protection, or access control checks. While the current implementation uses hardcoded filenames (`'decoy.txt'`, `'flag.txt'`), the pattern demonstrates unsafe filesystem interaction habits. If any part of these paths became user-controllable, directory traversal vulnerabilities (CWE-22) would immediately emerge.

**Output Encoding: Partial Protection.** The Jinja2 templating engine provides **default auto-escaping for .html files**, which protects against Cross-Site Scripting (XSS) by converting HTML special characters (`<`, `>`, `&`, `"`, `'`) to HTML entities. The flag value displayed in `index.html:14` (`{{ flag }}`) is auto-escaped, preventing XSS if the flag contained malicious JavaScript. However, the application does not explicitly configure auto-escaping (no `autoescape=True` parameter), relying on Jinja2 defaults. This is the only input validation control present in the entire application, and it only protects against XSS output injection, not the far more serious deserialization and file manipulation vulnerabilities.

### Background Processing: Not Present

The application performs no background job processing, no asynchronous task queuing, no scheduled tasks, and no worker processes separate from the HTTP request-response cycle. All operations occur synchronously within the context of handling HTTP requests. There are no Celery workers, no background threads spawned for long-running tasks, and no cron jobs or scheduled maintenance scripts. Therefore, there are no background processing security concerns such as privilege escalation through worker processes, insecure job deserialization (ironically, the HTTP handler already has this vulnerability), or unauthorized job submission to background queues.

---

## 6. Infrastructure & Operational Security

### Secrets Management: Critically Insecure

The application demonstrates **fundamentally flawed secret management practices** that would result in immediate compromise in any real-world scenario. The CTF flag (representing sensitive credentials or API keys in production contexts) is stored and transmitted through multiple insecure channels, each creating independent exposure vectors.

**Plaintext Storage in Environment Files (CRITICAL).** The actual flag value is stored unencrypted in `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/.env`:

```
FLAG="flag{f96e0e03-a965-4c0d-a9dd-dccb9dfcb22c}"
```

This file represents a **single point of failure** for secret confidentiality. If the `.env` file is committed to version control (git), the secret becomes permanently embedded in repository history and remains accessible even after deletion in future commits. Cloud-based git repositories (GitHub, GitLab, Bitbucket) store complete commit history indefinitely, meaning a single accidental commit of `.env` exposes the secret permanently. Automated secret scanning tools like GitHub's secret scanning, GitGuardian, or TruffleHog would detect this exposure and flag it as a security incident. Even if the file is properly included in `.gitignore`, developers with filesystem access to the deployment server, developers with access to backup archives, and any attacker who gains read access to the application directory can trivially extract the secret.

**Docker Build Argument Exposure (CRITICAL).** The Docker build process injects the flag as a build argument (Dockerfile:9 `ARG FLAG`) and uses it in a RUN command (Dockerfile:10 `RUN sed -i s/FLAG/$FLAG/g flag.txt`). **Docker build arguments are fundamentally insecure for secrets** because they are persisted in image metadata. Running `docker history <image_name>` on the built image reveals all build arguments in the intermediate layer commands, exposing the flag value to anyone with access to the Docker image. This includes developers who pull the image from registries, security scanners analyzing container images, and attackers who compromise container registries or gain access to image tarballs. Even if the image is deleted from the local system, registry providers retain image history, making the secret exposure permanent.

**No Secret Rotation Mechanisms.** The application has no capability to rotate secrets without rebuilding the Docker image and redeploying the entire application. Secrets are "baked in" at build time rather than injected at runtime, violating the **Twelve-Factor App** principle of storing configuration in the environment. There is no integration with secret management systems like **HashiCorp Vault**, **AWS Secrets Manager**, **Azure Key Vault**, or **Google Secret Manager** that provide secret rotation, access auditing, and time-limited access tokens. The static nature of secret storage means that if the flag is compromised (through any of the multiple exposure vectors), there is no rapid response capability to invalidate the leaked secret and issue a replacement.

### Configuration Security: No Separation of Environments

**No Environment-Based Configuration.** The application does not implement environment-specific configurations for development, staging, and production. All configuration is hardcoded in Python source code (port 80, template directory paths, file paths) or injected at build time (flag value). This violates security best practices that require **separation of code and configuration**, where sensitive settings and secrets should be provided at runtime through environment variables, configuration files outside the codebase, or secret management services. The lack of environment separation means the same secrets and configurations used in development are embedded in production containers, eliminating the ability to use dummy/test secrets in non-production environments.

**Security Headers Configuration: NOT IMPLEMENTED.** Analysis of the Uvicorn server configuration (Dockerfile:12 references the base image's server startup) reveals no security header configuration. HTTP responses from the application lack critical security headers:

- **Content-Security-Policy (CSP):** Not configured. The HTML template includes Bootstrap loaded from `cdn.jsdelivr.net` (index.html:7-9) with Subresource Integrity (SRI) hashes, which is good practice. However, the lack of a CSP header means there's no enforcement of trusted script sources, no protection against unauthorized inline scripts, and no mitigation for XSS attacks beyond Jinja2's output escaping.

- **Strict-Transport-Security (HSTS):** Not configured. Without HSTS headers, the application does not instruct browsers to enforce HTTPS connections. While the application runs on HTTP port 80 (Docker exposes port 80 per docker-compose.yml:7), production deployments would typically place this behind a reverse proxy or load balancer handling TLS termination. The lack of HSTS configuration means no TLS enforcement policy is communicated even if HTTPS were enabled.

- **X-Frame-Options:** Not configured. The application can be embedded in iframes on malicious websites, enabling clickjacking attacks where attackers overlay invisible iframes over legitimate-looking interfaces to trick users into performing unintended actions (though with no authentication, traditional clickjacking impact is limited).

- **X-Content-Type-Options:** Not configured. Without `X-Content-Type-Options: nosniff`, browsers may perform MIME-type sniffing, potentially interpreting uploaded files as executable content even if served with incorrect Content-Type headers.

**Infrastructure Security Headers:** Searches for infrastructure configuration files (Nginx configs, Kubernetes Ingress definitions, CDN configurations) that might define security headers at the infrastructure layer rather than application layer returned no results. The repository contains only the application code and Docker configuration, with no evidence of reverse proxies, API gateways, or CDN configurations that would add security headers. This means security headers are not implemented at any layer of the stack.

### External Dependencies: Minimal Attack Surface

**Direct External Dependencies: MINIMAL.** The application has extremely limited external dependencies. The Dockerfile (`app/Dockerfile:4`) installs only **lxml==5.2.2** (XML/HTML parsing library) beyond what's included in the base image. Dependency analysis shows:

- **lxml 5.2.2:** Released May 2024, a relatively recent version. This library has historical vulnerabilities including XML External Entity (XXE) injection attacks, but version 5.2.2 includes patches for known CVEs. Importantly, the application **does not use lxml in any network-accessible code**—it is installed but never imported in `main.py`. This suggests lxml may be a leftover dependency from development or intended for future features but currently presents no exploitable attack surface.

- **Base Image Dependencies:** The `tiangolo/uvicorn-gunicorn-fastapi:python3.9` base image includes FastAPI 0.116.0, Starlette 0.46.2, Pydantic 2.12.3, Uvicorn 0.35.0, and Gunicorn 23.0.0. These are all relatively recent versions (2024 releases) with active maintenance and no known critical vulnerabilities at the time of analysis. However, the Debian-based base image (~1.19 GB) includes the full operating system with potential vulnerabilities in OS-level packages that may not receive timely updates.

**Third-Party Service Integrations: NONE.** The application makes no outbound HTTP requests to external APIs, does not integrate with payment gateways, does not send emails through external SMTP services, does not use cloud storage services (S3, Azure Blob, GCS), does not connect to external authentication providers (OAuth, SAML, LDAP), and does not report metrics to external monitoring services. The HTML template does load Bootstrap CSS/JS from `cdn.jsdelivr.net`, but this is a client-side resource load that doesn't expose server-side attack surface. The complete lack of external service integrations eliminates supply chain attack vectors, third-party API credential compromise risks, and external service dependency outages.

### Monitoring & Logging: Inadequate for Security Operations

**Logging Implementation: MINIMAL.** The application uses Python's `print()` function for logging (main.py:29: `print('Loading pickle file')`), which is **not a structured logging framework**. Proper security logging would use Python's `logging` module with configurable log levels (DEBUG, INFO, WARNING, ERROR, CRITICAL), structured log formats (JSON for machine parsing), and contextual information (timestamps, request IDs, user identifiers, source IP addresses). The current implementation provides:

- **No security event logging:** No logs for failed authentication attempts (N/A - no authentication exists), no logs for authorization failures (N/A - no authorization exists), no logs for suspicious input patterns, and no logs for file access operations (critical given the file-based flag storage).

- **No audit trail:** No record of who accessed which flag files, when files were modified, or which clients uploaded pickle files. The only logged event is the generic message "Loading pickle file" without context about the client IP, file size, filename, or timestamp beyond what the Uvicorn web server logs.

- **Information disclosure risk:** While the current log message is benign, using `print()` statements without sanitization creates risk of logging sensitive data. If developers added logging for debugging purposes (e.g., `print(f"Flag value: {flag}")`), sensitive data would be exposed in logs accessible to infrastructure operators, log aggregation systems, and potentially log files in backups.

**Security Monitoring: NOT IMPLEMENTED.** No evidence of security monitoring tools, intrusion detection systems (IDS), or Security Information and Event Management (SIEM) integration. The Docker health check (`docker-compose.yml:9-13`) only performs availability monitoring (curling `/ping` endpoint), not security monitoring. There are no mechanisms to:

- Detect abnormal access patterns (rapid-fire requests indicating automated exploitation attempts)
- Alert on suspicious file uploads (large files, unusual file types, high upload frequency)
- Monitor for signs of compromise (unexpected file modifications, unusual process spawns)
- Track failed operations that might indicate attack reconnaissance
- Generate security metrics for compliance reporting or incident response

---

## 7. Overall Codebase Indexing

The **XBEN-036-24 "Green Pickle"** codebase exhibits a deliberately minimalist structure characteristic of Capture The Flag (CTF) challenge design, where complexity is intentionally limited to focus participant attention on specific vulnerability classes—in this case, insecure deserialization via Python's pickle module. The repository is organized as a self-contained Docker-based application with a flat directory hierarchy that prioritizes rapid deployment and straightforward source code review over enterprise-grade architectural patterns.

The **root directory** (`/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/`) contains configuration and orchestration files: `docker-compose.yml` for container orchestration, `.env` for environment variable storage (containing the CTF flag in plaintext), `Makefile` (which includes a parent directory common makefile via `include ../../common.mk` suggesting this is part of a larger CTF challenge repository structure), `README.md` for challenge documentation, and `benchmark.json`/`benchmark.yaml` files containing CTF challenge metadata (likely defining challenge difficulty, point values, and success criteria for automated evaluation platforms). Notably absent are CI/CD configuration files (no `.github/workflows/`, `.gitlab-ci.yml`, or `Jenkinsfile`), infrastructure-as-code definitions (no Terraform, Pulumi, or CloudFormation), and dependency lock files (no `requirements.txt` or `Pipfile.lock`), indicating this is a standalone educational application rather than production infrastructure.

The **`app/` subdirectory** contains the application implementation with equally minimalist structure. The primary application logic resides in `main.py` (44 lines total including whitespace), which imports FastAPI, defines three HTTP endpoints, and implements the vulnerable pickle deserialization pattern. The `templates/` subdirectory contains a single HTML file (`index.html`) implementing the Jinja2 template for flag display and file upload form using Bootstrap for basic styling. Two plaintext data files (`flag.txt` containing a placeholder "FLAG" string to be replaced during build, and `decoy.txt` containing the string "this is just the decoy") provide the file-based data storage. The `Dockerfile` defines the container build process using the official FastAPI base image, installing lxml as the sole additional dependency, and performing sed-based string replacement to inject the real flag value at build time.

**Security-relevant organizational observations** include the complete absence of a `tests/` directory, indicating no unit tests, integration tests, or security test suites exist to validate secure behavior or detect regressions. There is no `docs/` directory with security architecture documentation, threat models, or secure coding guidelines. The lack of a `scripts/` directory means no auxiliary tooling exists for secret rotation, security scanning, or deployment validation. The absence of `.github/` or `.gitlab/` directories confirms no automated security scanning (Dependabot, CodeQL, Snyk) is configured in CI/CD pipelines. Most critically for security discovery, **the flat structure makes all security-relevant components immediately visible**: the main application logic is a single 44-line Python file, secret storage is a single `.env` file, and the attack surface is three HTTP endpoints defined consecutively in one file. This discoverability is beneficial for penetration testing reconnaissance—there are no deeply nested directories to search, no complex module structures to understand, and no obfuscation hindering vulnerability identification. For security professionals, this structure represents the "ideal" target: maximum vulnerability with minimum complexity, allowing rapid exploitation focused on the core insecure deserialization pattern without navigating authentication layers, complex authorization logic, or distributed system components.

---

## 8. Critical File Paths

The following file paths are categorized by their security relevance for subsequent manual review and penetration testing activities:

### Configuration
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/.env` - Environment variables file containing plaintext CTF flag
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/docker-compose.yml` - Docker Compose orchestration defining port exposure and build arguments
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/Dockerfile` - Container build instructions including insecure secret injection via ARG
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/Makefile` - Build automation (includes parent common.mk)

### Authentication & Authorization
- **NONE** - No authentication or authorization code exists in this application

### API & Routing
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/main.py` - Complete application logic (44 lines) defining all three HTTP endpoints:
  - Lines 13-20: GET / endpoint (flag display)
  - Lines 23-37: POST / endpoint (vulnerable pickle deserialization) **CRITICAL**
  - Lines 40-42: GET /ping endpoint (health check)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/templates/index.html` - Jinja2 HTML template for flag display and file upload form

### Data Models & DB Interaction
- **NONE** - No database integration exists in this application

### Dependency Manifests
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/Dockerfile` - Line 4 defines lxml==5.2.2 as sole explicit dependency

### Sensitive Data & Secrets Handling
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/flag.txt` - Real CTF flag storage location
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/decoy.txt` - Decoy flag storage location
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/.env` - Plaintext flag value in environment file
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/main.py` - Lines 15-18 and 32-35 contain file reading logic for flag access

### Middleware & Input Validation
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/main.py` - Lines 28-30 contain CRITICAL insecure deserialization vulnerability with zero input validation

### Logging & Monitoring
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/main.py` - Line 29 contains minimal logging via print() statement

### Infrastructure & Deployment
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/docker-compose.yml` - Service definition exposing port 80 with health check configuration
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/Dockerfile` - Container build process with insecure secret handling at Lines 9-10

---

## 9. XSS Sinks and Render Contexts

### Executive Summary: No Exploitable XSS Sinks Identified

Comprehensive analysis of the network-accessible attack surface identified **ZERO traditional XSS (Cross-Site Scripting) sinks** in the XBEN-036-24 application. This finding is significant: while the application has catastrophic security failures in authentication, authorization, and input validation for deserialization, its handling of HTML output contexts demonstrates appropriate use of Jinja2's default auto-escaping protections that prevent XSS vulnerabilities.

### Analysis Methodology

Systematic searches were conducted across all network-accessible components for XSS sink patterns across multiple render contexts:

**HTML Body Context Sinks Searched:**
- `innerHTML`, `outerHTML` property assignments
- `document.write()`, `document.writeln()` calls
- `insertAdjacentHTML()`, `createContextualFragment()` methods
- jQuery sinks: `.add()`, `.after()`, `.append()`, `.before()`, `.html()`, `.prepend()`, `.replaceWith()`, `.wrap()`
- **Result:** No instances found in application JavaScript (no custom JavaScript exists in the application)

**HTML Attribute Context Sinks Searched:**
- Event handlers: `onclick`, `onerror`, `onmouseover`, `onload`, `onfocus` attributes with user-controlled values
- URL-based attributes: `href`, `src`, `formaction`, `action` with user-controlled destinations
- `style` attribute with user-controlled CSS
- `iframe` `srcdoc` with user-controlled content
- **Result:** No dynamic attribute construction with user input found

**JavaScript Context Sinks Searched:**
- `eval()` function calls
- `Function()` constructor with dynamic strings
- `setTimeout()` / `setInterval()` with string arguments (function form is safe)
- Direct user data interpolation within `<script>` tags
- **Result:** No JavaScript context sinks found; application contains no custom JavaScript code

**Template Injection Sinks Searched:**
- Jinja2 `|safe` filter usage (disables auto-escaping)
- `{% autoescape false %}` directives
- Dynamic template compilation with user input
- **Result:** No unsafe template rendering patterns found

### Detailed Template Variable Analysis

The single instance of server-side data interpolation in the application occurs in `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/templates/index.html` at line 14:

```html
<h5>The current flag is: {{ flag }} </h5>
```

**Render Context:** HTML body context (text content within an `<h5>` heading element)

**Data Source:** The `flag` variable originates from filesystem reads in `main.py` (lines 15-18 for GET endpoint, lines 32-35 for POST endpoint):

```python
if os.path.exists('decoy.txt'):
    flag = open('decoy.txt').read()
else:
    flag = open('flag.txt').read()
```

**User Control Assessment:** The `flag` variable is **NOT user-controlled through network-accessible inputs**. Its value comes from reading local files (`decoy.txt` or `flag.txt`) whose contents are determined at container build time. While an attacker can manipulate *which* file is read by exploiting the pickle deserialization vulnerability to delete `decoy.txt`, the attacker cannot control the *contents* of these files through network requests alone. The files are written during Docker image build and are read-only within the running container's normal operation.

**Auto-Escaping Analysis:** Jinja2Templates in FastAPI enables auto-escaping **by default for .html files**. The application initializes templates with `templates = Jinja2Templates(directory="templates")` at `main.py:10` without explicitly disabling auto-escaping. This means Jinja2 will automatically convert HTML special characters to safe entities:

- `<` → `&lt;`
- `>` → `&gt;`
- `&` → `&amp;`
- `"` → `&quot;`
- `'` → `&#x27;`

**Exploitation Feasibility:** Even if an attacker could somehow inject malicious content into `flag.txt` or `decoy.txt` (which would require RCE via the pickle vulnerability first, at which point XSS is no longer the primary concern), Jinja2's auto-escaping would neutralize HTML/JavaScript payloads. For example, if a flag contained `<script>alert('XSS')</script>`, it would be rendered as `&lt;script&gt;alert('XSS')&lt;/script&gt;` in the HTML, displaying as literal text rather than executing.

**Verdict:** **NOT VULNERABLE to XSS.** This template usage demonstrates secure coding practices for output encoding, representing one of the few security controls correctly implemented in this application.

### XSS Sink Summary Table

| Sink Type | Instances Found | Exploitable | Network Accessible |
|-----------|----------------|-------------|-------------------|
| HTML Body Context (innerHTML, etc.) | 0 | No | N/A |
| HTML Attribute Context (event handlers, URLs) | 0 | No | N/A |
| JavaScript Context (eval, Function()) | 0 | No | N/A |
| Template Injection (|safe, autoescape false) | 0 | No | N/A |
| **Total XSS Sinks** | **0** | **No** | **N/A** |

### Client-Side Code Analysis

**JavaScript Code:** The application contains **no custom JavaScript code**. The only JavaScript present is Bootstrap library code loaded from CDN (`cdn.jsdelivr.net/npm/bootstrap@4.3.1/dist/js/bootstrap.min.js`), which is loaded with Subresource Integrity (SRI) verification:

```html
<script src="https://cdn.jsdelivr.net/npm/bootstrap@4.3.1/dist/js/bootstrap.min.js"
        integrity="sha384-JjSmVgyd0p3pXB1rRibZUAYoIIy6OrQ6VrjIEaFf/nJGzIxFDsf4x0xIM+B07jRM"
        crossorigin="anonymous"></script>
```

The SRI hash ensures that if the CDN content is tampered with, browsers will refuse to execute the modified code. This is a security best practice for external resource loading. Since there is no custom JavaScript processing user input, there are no client-side XSS sinks to exploit.

**Form Actions:** The file upload form at `index.html:30-36` uses a static, hardcoded action attribute:

```html
<form method="post" enctype="multipart/form-data" action="/">
```

The `action="/"` is not constructed from user input or URL parameters, eliminating open redirect and form action manipulation attack vectors.

### Out-of-Scope Components Excluded

Per the scope definition, the following components were excluded from XSS analysis as they are not network-accessible:

- **Build scripts:** Makefile and parent common.mk (local execution only)
- **Docker build process:** Dockerfile commands (build-time, not runtime)
- **Documentation files:** README.md, benchmark.json, benchmark.yaml (metadata, not served by application)

---

## 10. SSRF Sinks

### Executive Summary: No SSRF Sinks Identified

Comprehensive analysis of the network-accessible codebase identified **ZERO Server-Side Request Forgery (SSRF) sinks** in the XBEN-036-24 application. The application makes **no outbound HTTP requests**, opens **no raw network sockets**, and performs **no URL-based operations** that could be manipulated to force the server to make unintended requests. This represents one of the few security-positive findings in this assessment: while the application is catastrophically vulnerable to deserialization attacks and lacks authentication, it does not expose SSRF attack surface in its intended functionality.

### Analysis Methodology and Sink Categories Searched

The analysis systematically searched for SSRF sink patterns across all categories defined in the penetration testing methodology:

### 1. HTTP(S) Client Libraries: NOT FOUND

**Libraries Searched:**
- `requests` library (requests.get, post, put, delete, patch, head, options)
- `urllib`, `urllib2`, `urllib3` (urlopen, Request, etc.)
- `httpx`, `aiohttp` (async HTTP clients)
- `curl` via subprocess calls

**Search Results:** No imports of HTTP client libraries exist in `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-036-24/app/main.py`. The application's import statements (lines 1-5) are limited to:

```python
import os
import pickle
from fastapi import FastAPI, UploadFile, File, Request
from fastapi.responses import HTMLResponse
from fastapi.templating import Jinja2Templates
```

No HTTP client functionality is imported, and no HTTP request methods are invoked in the application logic.

### 2. Raw Socket Operations: NOT FOUND

**Patterns Searched:**
- `socket.connect()`, `socket.create_connection()`
- `socket.socket()` instantiation followed by network operations
- Raw TCP/UDP socket creation and connection

**Search Results:** The `socket` module is not imported. The application performs no raw network operations, no socket programming, and no low-level network protocol implementation.

### 3. URL Opening Functions: LOCAL FILE OPERATIONS ONLY

**Patterns Searched:**
- `urllib.urlopen()` with URLs
- `open()` function with URL schemes (http://, ftp://, etc.)
- File operations with external sources

**Search Results:** The application uses `open()` function only for **local file reads**:

```python
# Lines 15-18 (GET endpoint)
if os.path.exists('decoy.txt'):
    flag = open('decoy.txt').read()
else:
    flag = open('flag.txt').read()
```

These file operations use **hardcoded relative paths** (`'decoy.txt'`, `'flag.txt'`) with no URL schemes, no remote protocols, and no user-controlled path components. While the use of `open()` without context managers represents poor coding practice (resource leak risk), it does not constitute an SSRF vulnerability. The files are local to the container filesystem with no network fetching involved.

### 4. Redirect & "Next URL" Handlers: NOT FOUND

**Patterns Searched:**
- `redirect()`, `RedirectResponse` with user-controlled URLs
- HTTP Location header manipulation
- "next", "return_url", "redirect_uri" parameters

**Search Results:** No redirect functionality exists in the application. All endpoints return either HTML responses (`HTMLResponse` via Jinja2Templates) or JSON responses (the `/ping` endpoint returns `{"ping": "pong"}`). No HTTP redirects (3xx status codes) are issued, and no user-controlled URL parameters influence response destinations.

### 5. Headless Browsers & Render Engines: NOT FOUND

**Patterns Searched:**
- Puppeteer (`page.goto`, `page.setContent`)
- Playwright (`page.navigate`, `page.route`)
- Selenium WebDriver navigation
- PDF generators (wkhtmltopdf, WeasyPrint, Puppeteer PDF)

**Search Results:** No headless browser libraries are installed or imported. The Dockerfile installs only `lxml==5.2.2` beyond base dependencies, and lxml is **never imported or used** in the application code. There are no PDF generation features, no screenshot capabilities, and no server-side rendering of external content.

### 6. Media Processors: NOT FOUND

**Patterns Searched:**
- ImageMagick, GraphicsMagick, Pillow/PIL, OpenCV
- FFmpeg, video processing libraries
- Image optimization services with URL parameters

**Search Results:** No media processing libraries are imported. The application does not handle images, videos, or media files. The only file upload functionality (pickle file upload) does not process the file content as media—it deserializes it as Python objects, representing a different vulnerability class (insecure deserialization, not SSRF).

### 7. Link Preview & Unfurlers: NOT FOUND

**Patterns Searched:**
- URL metadata extractors, oEmbed fetchers
- Social media card generators (Open Graph, Twitter Card)
- Link expansion services

**Search Results:** No link preview or URL unfurling functionality exists. The application displays only local flag file contents with no URL expansion, no external content fetching, and no metadata extraction from user-provided URLs.

### 8. Webhook Testers & Callback Verifiers: NOT FOUND

**Patterns Searched:**
- "Ping my webhook" functionality
- Outbound callback verification
- Health check notifications to external URLs
- Event delivery systems

**Search Results:** While the application has a `/ping` **endpoint** for health checking, this is an **inbound** health check (external systems query the application to verify it's running). The application does **not** make outbound requests to webhook URLs, does not verify callback URLs, and does not implement any notification or event delivery systems that would require external HTTP requests.

### 9. SSO/OIDC Discovery & JWKS Fetchers: NOT FOUND

**Patterns Searched:**
- OpenID Connect discovery endpoints (`.well-known/openid-configuration`)
- JWKS (JSON Web Key Set) fetchers
- OAuth authorization server metadata retrieval
- SAML metadata fetchers

**Search Results:** No authentication mechanisms exist in the application (see Section 3). There is no SSO integration, no OAuth flows, no OIDC discovery, and no JWKS fetching. The application does not validate JWT tokens, does not fetch public keys from external identity providers, and does not implement any federated authentication that would require external metadata retrieval.

### 10. Importers & Data Loaders: NOT FOUND

**Patterns Searched:**
- "Import from URL" functionality
- CSV/JSON/XML remote loaders
- RSS/Atom feed readers
- API data synchronization

**Search Results:** The application accepts file uploads but does not support "import from URL" functionality where users provide URLs to remote resources. The pickle file upload expects binary file content uploaded via multipart/form-data, not URLs to fetch. There are no feed readers, no data import wizards, and no remote data synchronization features.

### 11. Package/Plugin/Theme Installers: NOT FOUND

**Patterns Searched:**
- "Install from URL" features
- Package managers with remote sources
- Plugin/extension downloaders
- Theme installation from external repositories

**Search Results:** No plugin architecture, no extensibility mechanisms, and no dynamic code loading from external sources exist in this minimal CTF challenge application.

### 12. Monitoring & Health Check Frameworks: INFRASTRUCTURE ONLY

**Patterns Searched:**
- URL pingers making outbound requests
- Health check endpoints that probe external services
- Monitoring probe systems

**Search Results:** The Docker Compose configuration (`docker-compose.yml:9-13`) defines a health check:

```yaml
healthcheck:
  test: ["CMD", "curl", "-f", "http://localhost/ping"]
  timeout: 1s
  retries: 5
  interval: 10s
```

**SSRF Assessment:** This health check is **NOT an SSRF sink** because:
1. It is **infrastructure-level configuration** (Docker health check), not application code
2. It targets **localhost only** (`http://localhost/ping`) with hardcoded URL
3. It is **not user-controllable**—no network-accessible input can modify the health check target
4. It is **out of scope** per the penetration testing scope definition (local execution context, not callable via network requests)

### SSRF Sink Summary Table

| Sink Category | Sinks Found | User-Controllable | Network Accessible | Exploitable |
|---------------|-------------|-------------------|-------------------|-------------|
| HTTP(S) Clients | 0 | No | N/A | No |
| Raw Sockets | 0 | No | N/A | No |
| URL Openers | 0 | No | N/A | No |
| Redirect Handlers | 0 | No | N/A | No |
| Headless Browsers | 0 | No | N/A | No |
| Media Processors | 0 | No | N/A | No |
| Link Preview/Unfurlers | 0 | No | N/A | No |
| Webhook Testers | 0 | No | N/A | No |
| SSO/OIDC/JWKS | 0 | No | N/A | No |
| Data Importers | 0 | No | N/A | No |
| Plugin Installers | 0 | No | N/A | No |
| Monitoring/Health Checks (App) | 0 | No | N/A | No |
| **Total SSRF Sinks** | **0** | **N/A** | **N/A** | **No** |

### Potential Indirect SSRF via Insecure Deserialization

**Important Consideration:** While the application contains no direct SSRF sinks in its intended functionality, the **insecure deserialization vulnerability** (pickle.loads() on user input at `main.py:30`) enables **arbitrary code execution**, which an attacker could leverage to perform SSRF as a **post-exploitation activity**.

**Theoretical Attack Vector:**

```python
import pickle
import urllib.request

class SSRFExploit:
    def __reduce__(self):
        return (urllib.request.urlopen, ('http://internal-service/admin',))

malicious_pickle = pickle.dumps(SSRFExploit())
# Upload this pickle via POST /
# During deserialization, urllib.request.urlopen() executes, making request to attacker-controlled URL
```

**Why This Is NOT Reported as an SSRF Sink:**

1. **Vulnerability Classification:** This is **Remote Code Execution (RCE)**, not SSRF. The SSRF capability is a secondary effect of achieving arbitrary code execution.

2. **Attack Surface Definition:** SSRF sinks are application features that **intentionally make outbound requests** where user input controls request parameters. The pickle deserialization is not an outbound request feature—it's a deserialization operation that happens to enable code execution.

3. **Exploitation Context:** An attacker exploiting this path has already achieved RCE. At that point, SSRF becomes one of many post-exploitation capabilities (they could also read files, establish reverse shells, exfiltrate data, etc.). The primary vulnerability is the RCE, not the SSRF.

4. **Penetration Testing Methodology:** In vulnerability reporting, this would be documented as a **Critical RCE vulnerability** with SSRF mentioned as one possible post-exploitation technique, rather than cataloged as an SSRF sink.

### Conclusion

The XBEN-036-24 application contains **no direct SSRF sinks** in its network-accessible attack surface. The application does not implement any functionality that makes outbound HTTP requests, does not fetch external resources based on user input, and does not expose URL-based operations that could be manipulated for SSRF exploitation. While the insecure deserialization vulnerability could theoretically be leveraged to perform SSRF via arbitrary code execution, this is correctly classified as a post-RCE capability rather than a direct SSRF vulnerability. For penetration testers, this means SSRF-specific testing techniques (metadata service exploitation, internal port scanning via SSRF, DNS rebinding attacks) are not applicable to this target's primary attack surface—the focus should remain on exploiting the critical deserialization vulnerability for immediate code execution.

## Authenticated Scans

### SCHEMATHESIS
Status: skipped
No API schemas found

---
Report generated at: 2025-10-24T19:18:17.882Z