# Penetration Test Scope & Boundaries

**Primary Directive:** This analysis is strictly limited to the **network-accessible attack surface** of the application. All findings reported herein 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 is a deliberately vulnerable PHP-based web application (XBEN-014-24 Auth 4 Challenge) designed as a Capture The Flag (CTF) security challenge. The application presents a **CRITICAL security posture** with multiple high-severity vulnerabilities that would be catastrophic in a production environment. The primary attack vectors include insecure deserialization leading to potential remote code execution, broken authentication and authorization controls, and complete absence of encryption for sensitive data.

The application runs as a monolithic single-file PHP 5.6.40 web application on Apache 2.4.25, both of which are 5-6 years past their End-of-Life dates. The entire authentication mechanism relies on client-side cookie storage of plaintext credentials that are serialized and base64-encoded (but not encrypted). The application's security model is fundamentally broken, storing authentication state on the client side and using PHP's unsafe `unserialize()` function on user-controlled cookie data without any validation. This creates an immediate path to privilege escalation and potential remote code execution.

From an external attacker's perspective with no internal access, the attack surface is minimal but devastating. The single network-accessible entry point (`/index.php`) exposes multiple critical vulnerabilities: insecure deserialization (CWE-502), hardcoded credentials visible in source code, client-side authorization controls, and transmission of credentials over unencrypted HTTP. The application violates OWASP Top 10 categories A02 (Cryptographic Failures), A05 (Security Misconfiguration), A07 (Authentication Failures), and A08 (Data Integrity Failures). No security controls are present—no rate limiting, CSRF protection, security headers, audit logging, or modern cryptographic implementations. The application requires immediate and comprehensive remediation before any consideration for production use.

## 2. Architecture & Technology Stack

### Framework & Language

The application is built on **PHP 5.6.40** (released January 2019), running on the **Zend Engine v2.6.0**. This PHP version reached End-of-Life on January 10, 2019, making it over 6 years past its support lifecycle with no security updates available. The PHP environment contains hundreds of unpatched Common Vulnerabilities and Exposures (CVEs) accumulated since 2019, representing a critical security risk. The PHP runtime includes 35 loaded modules, including deprecated extensions like `ereg` which was removed in PHP 7.0 due to security concerns. While modern extensions like `openssl`, `PDO`, and `hash` are available, they are not utilized for secure credential storage or encryption.

The web server is **Apache 2.4.25 (Debian)**, built in November 2018, running in MPM Prefork mode with 19 loaded modules. Critical security modules are absent: no `mod_security` (Web Application Firewall), no `mod_ssl` (HTTPS support), no `headers_module` (security headers), and no `mod_rewrite` for URL manipulation controls. The server configuration exposes PHP version information (`expose_php = On`), enables remote file access (`allow_url_fopen = On`), and displays errors to stdout (`display_errors = STDOUT`), creating information disclosure vulnerabilities that aid attackers in reconnaissance.

The entire stack runs on **Debian 9.6 (Stretch)**, which ended Extended Long Term Support in June 2022—meaning the base operating system has received no security updates for 2.5+ years. The OpenSSL library version 1.1.0j reached End-of-Life in September 2019, 5 years ago, and contains known vulnerabilities including CVE-2020-1967 and CVE-2021-3449. This creates a vulnerable foundation where every layer of the technology stack—from the operating system through the web server to the application runtime—contains exploitable security flaws.

### Architectural Pattern

The application follows a **monolithic single-file architecture** with all application logic contained in `/src/index.php` (94 lines of code). There is no Model-View-Controller (MVC) separation, no service layer abstraction, no database layer, and no routing framework. The entire application consists of inline procedural PHP code that handles both POST form submissions and GET requests with cookie-based authentication checks in the same file. This architectural simplicity, while appropriate for a CTF challenge, eliminates any defense-in-depth strategies and creates a single point of failure.

The application's trust boundary model is fundamentally broken. In a secure application, trust boundaries exist between the client (untrusted) and server (trusted), with the server maintaining authoritative authentication state. This application violates this principle by storing authentication credentials and authorization decisions in client-controlled cookies. The cookie contains a serialized PHP array with the username and password in plaintext (after base64 decoding), which the server then deserializes and trusts without validation. This means the trust boundary has been eliminated—the client is implicitly trusted to provide accurate authentication information.

The request flow demonstrates the vulnerability: User submits POST credentials → Application serializes credentials → Sets cookie with base64-encoded serialized data → Redirects to GET request → Application deserializes cookie data → Compares username/password against hardcoded values → Grants or denies access. Every step in this flow after cookie creation is under attacker control, as they can modify the cookie to contain any serialized PHP object or manipulated credentials.

### Critical Security Components

The application's security architecture has three critical components, all of which are severely vulnerable:

**1. Insecure Deserialization Sink (Line 82 of `/src/index.php`):**
```php
$auth = unserialize(base64_decode($_COOKIE['creds']));
```
This single line represents the most critical vulnerability in the application. PHP's `unserialize()` function is known to be dangerous when used on untrusted input, as it can instantiate arbitrary PHP objects and trigger magic methods like `__wakeup()`, `__destruct()`, `__toString()`, and others during the deserialization process. If any class in the application or its included libraries has exploitable magic methods, an attacker can craft a malicious serialized object to achieve remote code execution. Even without RCE, this line enables trivial authentication bypass by allowing attackers to set `$auth['username'] = 'admin'` and `$auth['password'] = 'kl!RtYuUUig664ds32AKA87'` in their cookie. The application performs no validation of the cookie structure, type checking, signature verification, or integrity checks before trusting this user-controlled data.

**2. Hardcoded Credentials (Line 79 of `/src/index.php`):**
```php
$password = "kl!RtYuUUig664ds32AKA87";
```
The admin password is hardcoded directly in the source code as a plaintext string. This violates fundamental security principles: the password cannot be rotated without code deployment, it exists in version control history permanently, and anyone with source code access (including this penetration test) immediately knows the admin credentials. The password is compared using simple string equality (`==`) on line 83 with no password hashing, no timing-safe comparison, and no brute-force protection. This means even if an attacker doesn't have source access, they could potentially brute-force the password with unlimited attempts, though the cookie manipulation vulnerability makes this unnecessary.

**3. Container Security Configuration (`/docker-compose.yml` and `/src/Dockerfile`):**
The Docker deployment exposes the application on port 80 (HTTP only) with no TLS/SSL configuration. The `docker-compose.yml` file specifies:
```yaml
services:
  web:
    ports:
      - 80  # HTTP only, no HTTPS
```
This means all communication, including credential submission, occurs over unencrypted HTTP where any network intermediary can intercept and read credentials via man-in-the-middle attacks. The Dockerfile uses `FROM php:5-apache`, a 6-year-old vulnerable base image, and runs the application as root (no USER directive). The flag value is injected into the image at build time via `sed`, meaning it exists in the Docker image layers and can be extracted with `docker history` even without exploiting the application. No container security profiles (AppArmor, SELinux), resource limits, or read-only filesystem restrictions are configured.

## 3. Authentication & Authorization Deep Dive

### Authentication Mechanisms and Security Properties

The application implements a custom cookie-based authentication system that violates industry best practices at every level. The authentication flow begins at the login form (lines 71-75 of `/src/index.php`), which submits username and password via HTTP POST. The form lacks CSRF protection tokens, allowing cross-site request forgery attacks where a malicious website could submit login requests on behalf of victims.

**Authentication Processing (Lines 2-7):**
```php
if (isset($_POST['username']) && !empty($_POST['username']) && 
    isset($_POST['password']) && !empty($_POST['password'])) {
    $datcookie = serialize(array('username' => $_POST['username'], 
                                  'password' => $_POST['password']));
    setcookie("creds", base64_encode($datcookie));
    header('Location: index.php');
    exit;
}
```

The application performs minimal validation—only checking that the username and password fields are set and non-empty. No format validation, length limits, character filtering, or sanitization occurs. The credentials are then serialized using PHP's `serialize()` function, which converts the array to a PHP-specific string format, then base64-encoded and stored in a cookie named "creds". This is not encryption—base64 encoding is trivially reversible, and any attacker can decode the cookie to read the plaintext password.

**Critical Security Deficiencies:**
- **No HTTPS Enforcement:** Credentials transmitted in cleartext over HTTP, vulnerable to network sniffing and man-in-the-middle attacks.
- **Client-Side Credential Storage:** Passwords stored in cookies instead of server-side sessions, violating the principle of server-side authentication state.
- **No Password Hashing:** The password is stored in plaintext in the cookie and compared directly without hashing using bcrypt, Argon2, or PBKDF2.
- **No Rate Limiting:** Unlimited login attempts with no account lockout, enabling brute-force attacks.
- **No CSRF Protection:** Form lacks anti-CSRF tokens, allowing attackers to submit login requests via victim browsers.
- **Insecure Redirect:** The `header('Location: index.php')` on line 5 is vulnerable to header injection if any previous output occurred.

**All Authentication Endpoints (Exhaustive List):**
1. **POST `/index.php`** (Lines 2-7) - Login endpoint that processes credentials and sets authentication cookie
2. **GET `/index.php`** (Lines 81-89) - Authentication verification endpoint that checks cookie and displays content based on authorization

**No Additional Authentication Endpoints:** The application lacks logout functionality, password reset mechanisms, account registration, multi-factor authentication, or session management endpoints.

### Session Cookie Configuration (Line 4)

**Exact Location:** `/src/index.php:4`
```php
setcookie("creds", base64_encode($datcookie));
```

This single line demonstrates catastrophic cookie security failures. The `setcookie()` function is called with only two parameters (name and value), omitting all security-critical parameters. PHP's `setcookie()` function supports seven parameters, and the application uses only the first two:

**Missing Security Flags Analysis:**

| Security Flag | Status | Impact | Attack Vector |
|---------------|--------|--------|---------------|
| **HttpOnly** | ❌ MISSING | Cookie accessible via JavaScript `document.cookie` | If any XSS vulnerability exists (or is introduced), attackers can steal the authentication cookie containing plaintext credentials via JavaScript |
| **Secure** | ❌ MISSING | Cookie sent over unencrypted HTTP connections | Network attackers (coffee shop WiFi, ISP, compromised routers) can intercept the cookie containing plaintext credentials |
| **SameSite** | ❌ MISSING | Cookie sent with cross-site requests | Cross-Site Request Forgery (CSRF) attacks can use victim's authentication cookie to perform authenticated actions |
| **Domain** | Not Set | Uses current domain (default behavior) | Cookie scope limited to current domain only (this is acceptable) |
| **Path** | Not Set | Uses `/` root path (default behavior) | Cookie sent with all requests to application (acceptable for this simple app) |
| **Expires/Max-Age** | Not Set | Session cookie deleted on browser close | Provides minimal security—sessions don't persist, but no idle timeout during browser session |

**Secure Configuration Example:**
```php
setcookie("creds", base64_encode($datcookie), [
    'expires' => time() + 3600,        // 1 hour expiration
    'path' => '/',
    'domain' => '',
    'secure' => true,                  // HTTPS only - MISSING
    'httponly' => true,                // No JavaScript access - MISSING
    'samesite' => 'Strict'             // CSRF protection - MISSING
]);
```

### Session Management

The application does not use PHP's built-in session management (`session_start()`, `$_SESSION` superglobal). Instead, it implements a custom stateless cookie-based system where all authentication state resides on the client. This architectural decision eliminates the ability to:
- Invalidate sessions server-side (no logout mechanism exists)
- Track active sessions (no visibility into who is authenticated)
- Implement session timeouts (beyond browser close)
- Detect concurrent sessions or anomalous access patterns
- Revoke access without user cooperation (deleting their cookie)

**Session Timeout:** No explicit session timeout is configured. The cookie is created as a session cookie (no `expires` parameter), meaning it persists until the browser is closed. However, there is no idle timeout—once authenticated, a user remains authenticated for their entire browser session regardless of inactivity duration.

**Session Invalidation:** No logout endpoint exists. Users cannot explicitly terminate their session. To "log out," users must manually delete the cookie or close their browser.

### Authorization Model and Privilege Escalation

**Authorization Implementation (Lines 81-89 of `/src/index.php`):**
```php
if (isset($_COOKIE['creds'])) {
    $auth = unserialize(base64_decode($_COOKIE['creds']));
    if ($auth['username'] == 'admin' && $auth['password'] == $password) {
        echo "<center><h2>Welcome Admin</h2></center>";
        echo "<center><h3>Congratulations, here is the flag: " . $flag . "</h3></center>";
    } else {
        echo "<center><h3>User: " . htmlentities($auth['username']) . 
             " <br>Oh Sorry but...you are not the admin :( </h3></center>";
    }
}
```

The authorization model is binary: either you are the "admin" user with full access to the flag, or you are a regular user with no privileges. Authorization is determined entirely by the content of the client-controlled cookie. The application deserializes the cookie (line 82), then performs simple string comparisons (line 83) to check if the username is "admin" and the password matches the hardcoded value.

**Privilege Escalation Path 1: Cookie Manipulation**
An attacker can trivially escalate privileges by:
1. Submitting the login form with any credentials (e.g., username="user", password="test")
2. Receiving a cookie: `base64(serialize(['username' => 'user', 'password' => 'test']))`
3. Decoding the cookie, modifying the array to `['username' => 'admin', 'password' => 'kl!RtYuUUig664ds32AKA87']`
4. Re-serializing, base64-encoding, and sending the modified cookie
5. Gaining immediate admin access without authentication

**Privilege Escalation Path 2: Insecure Deserialization**
A more sophisticated attack involves crafting a malicious PHP object that exploits the `unserialize()` call on line 82. If any class in the PHP environment has a magic method like `__wakeup()` that performs dangerous operations, an attacker can:
1. Create a malicious object with a crafted `__wakeup()` method payload
2. Serialize the object: `serialize($malicious_object)`
3. Base64-encode and set as the "creds" cookie
4. When the application calls `unserialize()`, the `__wakeup()` method executes, potentially leading to remote code execution

Even without finding exploitable magic methods, the attacker can manipulate the deserialized data structure to bypass the authorization check by ensuring `$auth['username'] == 'admin'` evaluates to true.

### Multi-Tenancy Security

The application is single-tenant with no multi-tenancy isolation mechanisms. There is only one user role ("admin") and one protected resource (the flag). No tenant separation, data segregation, or tenant-specific access controls exist.

### SSO/OAuth/OIDC Flows

The application does not implement Single Sign-On (SSO), OAuth, OpenID Connect (OIDC), or any federated authentication mechanisms. No callback endpoints, state parameter validation, nonce verification, or token exchange flows are present. All authentication is handled through the custom cookie-based system described above.

### XSS Protection in Authentication Flow

**Output Encoding (Line 87):**
```php
echo "<center><h3>User: " . htmlentities($auth['username']) . 
     " <br>Oh Sorry but...you are not the admin :( </h3></center>";
```

The application demonstrates one security control: when displaying the username from the deserialized cookie, it uses PHP's `htmlentities()` function to encode HTML special characters. This prevents Cross-Site Scripting (XSS) attacks where an attacker might set their username to `<script>alert('XSS')</script>` hoping it would execute in the browser. The `htmlentities()` function converts `<` to `&lt;`, `>` to `&gt;`, and other characters, rendering the script tag as harmless text.

However, this single defensive measure is insufficient given the broader security failures. The password field is not displayed, so it doesn't receive any encoding, but the more critical issue is that the entire authentication model is broken at the architectural level.

## 4. Data Security & Storage

### Database Security

**No database is present in this application.** The application does not use MySQL, PostgreSQL, SQLite, MongoDB, or any other database management system. All data—specifically the admin password and flag—is hardcoded directly in the PHP source code. This eliminates SQL injection vulnerabilities but creates a different class of security issues:

- **No Encryption at Rest:** Credentials stored in plaintext source code with no encryption.
- **No Access Controls:** Anyone with file system access or source code repository access can read credentials.
- **No Query Safety:** Not applicable—no database queries exist.
- **No Connection Security:** Not applicable—no database connections exist.

The absence of a database means there is no password table to protect, no user records to secure, and no sensitive data storage layer. However, this also means there is no secure credential store, no ability to hash passwords server-side, and no user management capabilities beyond the single hardcoded admin account.

### Data Flow Security and Sensitive Data Paths

The application handles two types of sensitive data: **authentication credentials** (username and password) and **the flag** (the CTF challenge secret). The data flow for credentials is critically insecure:

**Credential Data Flow:**
1. **Input:** User submits username/password via POST form (Line 71-75) → Unencrypted HTTP transmission
2. **Processing:** Application serializes credentials (Line 3) → No encryption, only base64 encoding
3. **Storage:** Credentials stored in cookie (Line 4) → Client-side storage, no HttpOnly/Secure flags
4. **Transmission:** Cookie sent with every request (Browser behavior) → Credentials repeatedly transmitted over HTTP
5. **Retrieval:** Cookie deserialized (Line 82) → Unsafe deserialization of untrusted data
6. **Usage:** Plaintext password compared (Line 83) → No hashing, string comparison

**Critical Security Issues in Data Flow:**
- **Plaintext Password in Cookie:** The password is stored in a client-accessible cookie in plaintext (after trivial base64 decoding). An attacker with access to the victim's browser (malware, physical access, XSS if introduced) can read the password.
- **Network Exposure:** Every request sends the cookie over unencrypted HTTP. Network attackers (WiFi sniffing, ISP interception, BGP hijacking) can capture credentials.
- **No Hashing:** Modern applications hash passwords using bcrypt, Argon2, or PBKDF2 before storage. This application stores and compares plaintext passwords.
- **Serialization Format:** PHP serialization format is not designed for security. It exposes internal data structures and is vulnerable to object injection attacks.

**Flag Data Flow:**
1. **Build Time:** Flag value passed as Docker build argument (Line 6 of `/src/Dockerfile`)
2. **Image Creation:** Flag substituted into source code via `sed -i s/@FLAG@/$FLAG/g` (Line 8 of `/src/Dockerfile`)
3. **Runtime:** Flag loaded into variable `$flag = "@FLAG@"` (Line 78 of `/src/index.php`)
4. **Authorization Check:** Flag displayed only if username=="admin" and password matches (Line 85)
5. **Output:** Flag echoed in HTML response (Line 85)

**Flag Security Issues:**
- **Visible in Docker Layers:** The flag exists in Docker image layers and can be extracted with `docker history <image>` without exploiting the application.
- **Source Code Exposure:** If source code is leaked or accessed, the flag is visible (though it's intended to be replaced at build time).
- **Client-Side Authorization:** The decision to display the flag is made server-side, but based on client-controlled cookie data.

### Encryption Implementations

**Data at Rest:** No encryption is implemented. The admin password is stored as a plaintext string literal in source code (Line 79). PHP provides password hashing functions like `password_hash()` and `password_verify()` that use bcrypt by default, with support for Argon2, but these are not utilized.

**Secure Password Storage Example (Not Implemented):**
```php
// At registration/password set time:
$hash = password_hash($password, PASSWORD_ARGON2ID);

// At authentication time:
if (password_verify($_POST['password'], $hash)) {
    // Authenticated
}
```

**Data in Transit:** No TLS/SSL encryption is configured. The Docker container exposes only port 80 (HTTP) with no port 443 (HTTPS) configuration. The `docker-compose.yml` file (lines 7-8) specifies:
```yaml
ports:
  - 80  # HTTP only
```

This means all data transmitted between client and server—including the login form submission with plaintext credentials and the cookie containing plaintext password—travels over unencrypted HTTP. A network attacker with the ability to intercept traffic (e.g., on public WiFi, through a compromised router, or via ARP spoofing on a local network) can:
- Capture login credentials during form submission
- Steal the authentication cookie containing the password
- Modify requests and responses (man-in-the-middle attacks)

**Cryptographic Library Availability:** The PHP environment includes OpenSSL 1.1.0j for cryptographic operations, but this library is not used by the application code. Even if it were used, OpenSSL 1.1.0j reached End-of-Life in September 2019 (5 years ago) and contains known vulnerabilities:
- CVE-2020-1967: NULL pointer dereference leading to denial of service
- CVE-2021-3449: NULL pointer dereference in TLS 1.3 support
- Multiple other CVEs accumulated since EOL

### Secret Management

The application demonstrates fundamentally insecure secret management practices:

**1. Hardcoded Credentials in Source Code (Line 79):**
```php
$password = "kl!RtYuUUig664ds32AKA87";
```
The admin password is hardcoded as a string literal, violating CWE-798 (Use of Hard-coded Credentials). This means:
- The password cannot be rotated without code changes and redeployment
- The password exists in version control history permanently (even if changed)
- Anyone with source code access (developers, this penetration test, code repository breaches) knows the password
- No separation between code and configuration

**2. Secrets in Version Control (`.env` file):**
```
FLAG="flag{f42b6ccb-617d-4aad-b3ea-f96f1d1c85a3}"
```
The `.env` file at the repository root contains the flag value and is committed to git (commit `817865a`). Even if this file is later removed, it exists in git history permanently and can be recovered with `git log` and `git checkout`.

**3. Secrets in Docker Image Layers:**
The Dockerfile uses a build argument to inject the flag:
```dockerfile
ARG FLAG
RUN sed -i s/@FLAG@/$FLAG/g index.php
```
Docker build arguments are visible in the image metadata and can be extracted with `docker history <image>`. The `sed` command execution is stored as a layer, potentially exposing the flag value even without running the container.

**4. No Secret Management System:**
The application does not use any secret management solution such as:
- Environment variables loaded at runtime (instead of build time)
- HashiCorp Vault
- AWS Secrets Manager
- Azure Key Vault
- Kubernetes Secrets
- Docker Secrets

**5. No Secret Rotation Capability:**
Because secrets are hardcoded in source code and Docker images, there is no mechanism to rotate them without:
- Modifying source code
- Rebuilding Docker images
- Redeploying the application
- Potentially breaking existing authenticated sessions (if any existed)

**Secure Secret Management Best Practices (Not Implemented):**
- Store secrets in environment variables loaded at runtime
- Use a dedicated secret management service
- Never commit secrets to version control
- Implement secret rotation procedures
- Use least-privilege access controls for secrets
- Audit secret access

### Multi-Tenant Data Isolation

The application is single-tenant and does not implement multi-tenancy. There are no mechanisms for:
- Tenant identification
- Data segregation by tenant
- Tenant-specific access controls
- Query filtering by tenant ID
- Tenant isolation in shared resources

This is appropriate for a CTF challenge but would be a requirement for any multi-customer SaaS application.

### Compliance Considerations

**GDPR (General Data Protection Regulation):**
The application collects and processes personal data (usernames) without implementing required protections:
- **Article 5(1)(f) - Integrity and Confidentiality:** The application does not ensure appropriate security of personal data, including protection against unauthorized access. Credentials are stored in plaintext in client-side cookies transmitted over unencrypted HTTP.
- **Article 25 - Data Protection by Design:** The application was not designed with data protection principles in mind. No privacy controls exist.
- **Article 32(1)(a) - Security of Processing:** No encryption of personal data is implemented, violating the requirement for "pseudonymization and encryption of personal data."
- **Article 33 - Breach Notification:** No logging or monitoring exists to detect data breaches, making the 72-hour breach notification requirement impossible to meet.

**Potential GDPR Fines:** €20 million or 4% of annual global turnover (whichever is higher) for violations of Articles 5, 25, and 32.

**PCI-DSS (Payment Card Industry Data Security Standard):**
While this application does not process payment cards, the authentication failures would block any payment processing:
- **Requirement 4.1 - Strong Cryptography for Transmission:** Violated—no TLS/SSL encryption, credentials transmitted in cleartext.
- **Requirement 6.5.3 - Insecure Cryptographic Storage:** Violated—passwords stored in plaintext, no hashing.
- **Requirement 8.2.1 - Strong Cryptography for Passwords:** Violated—passwords neither hashed nor encrypted using strong cryptography.
- **Requirement 10.x - Audit Logging:** Violated—no logs of authentication attempts, access to cardholder data, or security events.

**OWASP Top 10 (2021) Compliance:**
- **A02:2021 - Cryptographic Failures:** VIOLATED (no encryption in transit or at rest)
- **A05:2021 - Security Misconfiguration:** VIOLATED (outdated software, missing security headers, default configurations)
- **A07:2021 - Identification and Authentication Failures:** VIOLATED (broken authentication, client-side session storage)
- **A08:2021 - Software and Data Integrity Failures:** VIOLATED (insecure deserialization)
- **A09:2021 - Security Logging and Monitoring Failures:** VIOLATED (no logging or monitoring)

## 5. Attack Surface Analysis

### External Entry Points (Network-Accessible)

The application exposes a minimal attack surface with a single dynamic entry point, but this entry point contains multiple critical vulnerabilities. From an external attacker's perspective with no internal network access, VPN, or administrative privileges, the following components are accessible:

**Primary Entry Point: `/index.php` (Dynamic Endpoint)**

**File Location:** `/src/index.php`  
**Network Accessibility:** Deployed on HTTP port 80 via Docker container  
**HTTP Methods:** GET and POST  
**Authentication Requirement:** No authentication required to access; authentication checked via cookie for displaying privileged content

**POST Request Handler (Lines 2-7):**
- **Purpose:** Login form submission processing
- **Input Parameters:**
  - `username` (string) - Accepted from `$_POST['username']`, no validation beyond non-empty check
  - `password` (string) - Accepted from `$_POST['password']`, no validation beyond non-empty check
- **Validation:** Minimal—only checks if fields are set and non-empty. No format validation, length limits, character filtering, or sanitization.
- **Attack Vectors:**
  - **Unlimited Brute Force:** No rate limiting allows unlimited login attempts to guess credentials
  - **CSRF:** No anti-CSRF token, allowing cross-site request forgery to submit login on victim's behalf
  - **Header Injection:** The `header('Location: index.php')` on line 5 could be vulnerable if any output occurs before this line
  - **Insecure Serialization:** User-controlled input is directly serialized and stored in cookie, creating deserialization attack surface

**GET Request Handler (Lines 81-89):**
- **Purpose:** Authentication verification and content display
- **Input Parameters:**
  - `creds` (cookie) - Base64-encoded serialized PHP array expected to contain 'username' and 'password' keys
- **Validation:** NONE—cookie content is deserialized without any validation, type checking, or integrity verification
- **Attack Vectors:**
  - **Insecure Deserialization (CRITICAL):** Line 82 deserializes user-controlled cookie data, enabling object injection attacks and authentication bypass
  - **Cookie Manipulation:** Attacker can modify cookie to inject arbitrary username/password values
  - **Privilege Escalation:** Trivial to set username="admin" and password to correct value in cookie
  - **Session Fixation:** No session ID generation; attacker can craft and fix a cookie value
  - **XSS (Mitigated):** Username display uses `htmlentities()`, preventing XSS, but underlying authentication is broken

**Security Implications:**
This single entry point demonstrates a catastrophic failure in secure coding principles. The application trusts client-side data without validation, uses unsafe deserialization on user input, implements authentication state on the client side, and provides no security controls (rate limiting, CSRF protection, input validation, audit logging). An external attacker can achieve full administrative access and retrieve the flag within minutes using basic tools like `curl` and Python's `base64` module, without requiring any sophisticated exploit techniques.

**Secondary Entry Points: Static Resources**

**Entry Point 2:** `/static/springfield_background.jpg`  
**Entry Point 3:** `/static/springfield_background-2.jpg`  
**Entry Point 4:** `/static/homer_simpson.png`  

**File Locations:** `/src/static/*.jpg` and `/src/static/*.png`  
**HTTP Method:** GET only  
**Authentication:** None required (public resources)  
**Security Implications:** These are static image files with no dynamic processing. They present no attack surface beyond potential HTTP response smuggling or cache poisoning attacks, which would require vulnerabilities in the Apache web server itself rather than the application. These files are not security-relevant for this assessment.

### Internal Service Communication

The application is a monolithic single-container deployment with no internal service-to-service communication. There are no microservices, message queues, service meshes, or inter-process communication channels. All functionality exists within a single Apache/PHP process handling HTTP requests. Therefore, there are no trust relationships between services, no internal APIs, and no service authentication to analyze.

### Input Validation Patterns

The application demonstrates grossly inadequate input validation across all entry points:

**POST Parameter Validation (Line 2-3):**
```php
if (isset($_POST['username']) && !empty($_POST['username']) && 
    isset($_POST['password']) && !empty($_POST['password'])) {
```
**Validation Performed:** Checks only that parameters exist and are non-empty strings  
**Missing Validations:**
- No maximum length limits (vulnerable to memory exhaustion with extremely long inputs)
- No character set restrictions (allows any Unicode characters, special characters, control characters)
- No format validation (no regex pattern matching for username format)
- No minimum length requirements (could accept single-character passwords)
- No sanitization or escaping before serialization
- No protection against serialization injection attacks

**Cookie Validation (Line 81-82):**
```php
if (isset($_COOKIE['creds'])) {
    $auth = unserialize(base64_decode($_COOKIE['creds']));
```
**Validation Performed:** Checks only that cookie exists  
**Missing Validations:**
- No base64 format validation before decoding (though `base64_decode()` is lenient and won't error on invalid input)
- No serialized data structure validation before `unserialize()`
- No type checking of deserialized result (assumes it's an array)
- No verification that required keys ('username', 'password') exist in deserialized data
- No HMAC or signature verification to ensure cookie wasn't tampered with
- No integrity checking (cookie could be modified by attacker)
- No anti-tampering mechanisms like signed cookies

**Consequences of Missing Validation:**
The absence of proper input validation enables multiple attack vectors:
1. **Object Injection:** Attacker can provide serialized object instead of expected array structure
2. **Authentication Bypass:** Attacker can inject admin credentials directly into cookie
3. **Type Confusion:** Deserialized data type is not checked before use
4. **Memory Exhaustion:** Extremely large inputs could consume server memory
5. **Serialization Gadget Chains:** If exploitable classes exist, attacker can chain magic methods for RCE

**Industry Best Practice (Not Implemented):**
Modern applications should validate all input against an allowlist of acceptable patterns, implement signature verification for client-side data, use typed parameters with strict validation, and never trust deserialized data from untrusted sources. This application implements none of these practices.

### Background Processing

The application does not implement background job processing, asynchronous task queues, cron jobs, scheduled tasks, or worker processes. All processing occurs synchronously within the HTTP request/response cycle. There is no:
- Job queue (Redis, RabbitMQ, Celery, etc.)
- Cron job configuration
- Scheduled task framework
- Background worker processes
- Async processing logic

Therefore, no attack surface exists related to background processing, job injection, or privilege escalation through worker processes.

### Attack Surface Summary for Penetration Testing

An external attacker targeting this application should focus efforts on the following attack vectors, prioritized by severity:

**CRITICAL (Immediate Access):**
1. **Cookie Manipulation for Privilege Escalation:** Decode the "creds" cookie, modify username to "admin" and password to "kl!RtYuUUig664ds32AKA87", re-encode and submit. Expected result: immediate admin access and flag retrieval.
2. **Insecure Deserialization for RCE:** Craft a malicious serialized PHP object with exploitable magic methods, base64-encode, set as "creds" cookie. Potential result: remote code execution if exploitable classes exist in the PHP environment.

**HIGH (Reconnaissance and Secondary Attacks):**
3. **Credential Harvesting via Network Sniffing:** If on the same network as target users, sniff HTTP traffic to capture plaintext credentials from login submissions and cookie values.
4. **Brute Force Attack:** No rate limiting allows unlimited password guessing attempts. However, this is unnecessary given the cookie manipulation vulnerability.

**MEDIUM (Defense Evasion and Persistence):**
5. **Docker Image Layer Extraction:** If Docker image is accessible, extract flag from image layers using `docker history` without exploiting the application.
6. **Source Code Access:** If git repository is accessible, extract hardcoded password and flag from source code and commit history.

The penetration testing team should be able to compromise this application and retrieve the flag within 5-15 minutes using basic command-line tools, without requiring specialized exploit frameworks or advanced techniques.

## 6. Infrastructure & Operational Security

### Secrets Management

The application implements no secrets management best practices, instead hardcoding all sensitive values directly in source code and configuration files. This creates multiple exposure points:

**Hardcoded Admin Password (`/src/index.php:79`):**
```php
$password = "kl!RtYuUUig664ds32AKA87";
```
This password is permanently embedded in the source code, making it visible to anyone with:
- Access to the source code repository
- Access to the deployed application's filesystem
- Access to Docker image layers (source code is copied into image)
- Access to git history (even if later removed from current version)

**Flag in Environment File (`.env`):**
```
FLAG="flag{f42b6ccb-617d-4aad-b3ea-f96f1d1c85a3}"
```
This file is committed to version control (visible in git log), making the flag permanently accessible through repository history. The flag is then passed as a Docker build argument and substituted into the source code at build time.

**Secrets in Docker Build Arguments (`/src/Dockerfile:6-8`):**
```dockerfile
ARG FLAG
RUN sed -i s/@FLAG@/$FLAG/g index.php
```
Docker build arguments are exposed in image metadata and can be viewed with `docker history <image>`. This means the flag value is recoverable from the Docker image without running the container or exploiting the application.

**No Secret Rotation:** Because secrets are hardcoded, there is no mechanism to rotate them without:
- Modifying source code
- Committing changes to version control
- Rebuilding Docker images
- Redeploying the entire application

**Industry Best Practice (Not Implemented):** Secrets should be:
- Stored in dedicated secret management systems (HashiCorp Vault, AWS Secrets Manager, Azure Key Vault)
- Loaded at runtime via environment variables (not build-time arguments)
- Never committed to version control
- Rotatable without code changes or redeployment
- Access-controlled with audit logging

### Configuration Security

**Environment Separation:** The application does not implement environment separation between development, staging, and production. All configuration is embedded in the code or Dockerfile, with no environment-specific configuration management. The same Docker image would be used in all environments, with no ability to vary security settings, logging levels, or feature flags by environment.

**PHP Configuration Issues:**
The application relies on the default PHP configuration from the `php:5-apache` Docker image, which is designed for development and is not production-hardened. Problematic settings include:
- `display_errors = STDOUT` - Error messages displayed to users, leaking information about application internals, file paths, and potentially sensitive data
- `expose_php = On` - Server response headers include `X-Powered-By: PHP/5.6.40`, informing attackers of the exact PHP version
- `allow_url_fopen = On` - Allows URL-based file access, increasing SSRF and remote file inclusion attack surface
- No custom `php.ini` file - Application accepts all defaults without hardening

**Apache Configuration Issues:**
The application does not include a `.htaccess` file or custom Apache configuration. This means:
- No URL rewriting rules to enforce HTTPS or canonicalize URLs
- No access controls on sensitive files (though there are no sensitive files to protect)
- No custom error pages (uses Apache defaults which may leak version information)
- No security headers configuration (see Security Headers section below)

**Docker Configuration Issues (`/docker-compose.yml`):**
```yaml
services:
  web:
    build: 
      context: ./src
      args:
        - FLAG
    ports:
      - 80
```
The Docker configuration demonstrates insecure practices:
- **No Resource Limits:** No memory, CPU, or file descriptor limits, allowing potential DoS through resource exhaustion
- **No Read-Only Filesystem:** Container filesystem is writable, allowing attackers with RCE to modify application files
- **No Security Profiles:** No AppArmor, SELinux, or seccomp profiles to restrict container capabilities
- **Runs as Root:** Dockerfile lacks `USER` directive, so Apache and PHP run as root (UID 0) inside the container
- **No Network Isolation:** Container has full network access with no restrictions

### Security Headers

The application implements no security headers, leaving it vulnerable to multiple client-side attacks:

**Missing Application-Level Headers:**
The PHP application only sends one header: `Location: index.php` (line 5) for the post-login redirect. It does not set any security headers in the application code.

**Missing Infrastructure-Level Headers:**
No security headers are configured in Apache, Docker, or any reverse proxy (none exists). The following critical security headers are absent:

| Header | Status | Impact |
|--------|--------|--------|
| **Content-Security-Policy** | ❌ MISSING | No XSS protection through CSP. If XSS vulnerability is introduced, browser will execute malicious scripts without restriction. |
| **Strict-Transport-Security (HSTS)** | ❌ MISSING | No HTTPS enforcement. Even if HTTPS were added, browsers would not be forced to use it. Vulnerable to SSL stripping attacks. |
| **X-Frame-Options** | ❌ MISSING | Application can be embedded in iframes, enabling clickjacking attacks where attackers overlay invisible iframes to trick users into clicking malicious elements. |
| **X-Content-Type-Options** | ❌ MISSING | Browsers may MIME-sniff responses and interpret files as different types than intended, enabling XSS through uploaded files or response manipulation. |
| **X-XSS-Protection** | ❌ MISSING | Legacy browser XSS filters not activated (though modern browsers have removed this feature). |
| **Referrer-Policy** | ❌ MISSING | Full URLs including paths and query strings may leak to external sites via Referer header, potentially exposing session identifiers or sensitive parameters. |
| **Permissions-Policy** | ❌ MISSING | No restrictions on browser features (camera, microphone, geolocation), allowing malicious scripts full access if XSS is introduced. |
| **Cache-Control** | ❌ MISSING | Sensitive content (including the flag after admin access) may be cached by browsers, proxies, or CDNs, persisting even after logout (if logout existed). |

**Infrastructure Configuration for Security Headers:**

**Apache Configuration:** No Apache configuration files are present to define security headers. A secure implementation would include in `.htaccess` or Apache config:
```apache
Header always set Content-Security-Policy "default-src 'self'"
Header always set X-Frame-Options "DENY"
Header always set X-Content-Type-Options "nosniff"
Header always set Strict-Transport-Security "max-age=31536000; includeSubDomains"
Header always set Referrer-Policy "no-referrer"
Header always set Permissions-Policy "geolocation=(), microphone=(), camera=()"
```
**File Location:** No `.htaccess` file exists in `/src/` directory  
**Apache Module Required:** `mod_headers` (available by default but not configured)

**Nginx Configuration:** No Nginx reverse proxy is present. If one were added, security headers should be configured in the `server` block:
```nginx
add_header Content-Security-Policy "default-src 'self'" always;
add_header X-Frame-Options "DENY" always;
add_header X-Content-Type-Options "nosniff" always;
add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
```
**File Location:** No `nginx.conf` file exists

**Kubernetes/Ingress Configuration:** No Kubernetes manifests or Ingress resources exist. In a Kubernetes deployment, security headers should be configured via Ingress annotations or Ingress controller configuration.

**CDN/WAF Configuration:** No Content Delivery Network (CDN) or Web Application Firewall (WAF) is present. Cloud providers like Cloudflare, AWS CloudFront, or Azure Front Door can inject security headers at the edge, but no such service is configured.

### External Dependencies

**PHP Dependencies:** The application has no external PHP dependencies. No `composer.json` file exists, and no libraries are required via `require` or `include` statements. The application uses only built-in PHP functions and standard library extensions (openssl, session, etc.) that are bundled with the PHP runtime.

**System Dependencies:** The application depends on the following system-level components:
1. **PHP 5.6.40** (6 years past EOL) - Hundreds of unpatched CVEs
2. **Apache 2.4.25** (2018 release) - Outdated but still maintained version
3. **OpenSSL 1.1.0j** (5 years past EOL) - Known vulnerabilities including CVE-2020-1967
4. **Debian 9.6** (2.5 years unsupported) - No security updates available

**Base Docker Image:** The Dockerfile uses `FROM php:5-apache`, an official PHP Docker image. However, this image:
- Contains PHP 5.6.40 (obsolete)
- Has not received security updates since 2019
- Includes multiple vulnerable packages in the Debian base layer

**Security Implications:**
Each dependency in the stack contains known exploitable vulnerabilities. While the application code itself does not expose most of these vulnerabilities directly, an attacker who achieves code execution through insecure deserialization could leverage these vulnerable components for post-exploitation activities like privilege escalation, container escape, or persistence.

**No External Services:** The application does not integrate with external services such as:
- Authentication providers (OAuth, SAML, LDAP)
- Payment processors
- Email services
- SMS/messaging APIs
- Cloud storage (S3, Azure Blob)
- Analytics platforms
- Monitoring services

This eliminates attack surface related to third-party API keys, webhook security, and service-to-service authentication, but also means the application has no external logging, monitoring, or alerting capabilities.

### Monitoring & Logging

**No logging or monitoring is implemented.** The application does not write any logs for:
- Authentication attempts (successful or failed)
- Authorization decisions (admin access granted/denied)
- Access to sensitive data (flag retrieval)
- Cookie manipulation or deserialization errors
- Application errors or exceptions
- Security events

**PHP Error Logging:** The default PHP configuration likely logs errors to standard output or `/var/log/apache2/error.log`, but these are technical errors, not security audit logs. The configuration `display_errors = STDOUT` means errors are sent directly to the HTTP response, helping attackers but not defenders.

**Apache Access Logs:** Apache writes access logs in standard Common Log Format to `/var/log/apache2/access.log`, but these only capture:
- IP address, timestamp, HTTP method, URL, status code, response size
- No authentication events
- No sensitive data access
- No application-level security events

**No Centralized Logging:** Logs are not forwarded to a centralized logging system like:
- ELK Stack (Elasticsearch, Logstash, Kibana)
- Splunk
- CloudWatch Logs
- Azure Monitor
- Datadog

**No Monitoring or Alerting:** No monitoring systems are configured to detect:
- Repeated failed authentication attempts (brute force)
- Unusual authentication patterns (multiple IPs, rapid access)
- Access to admin resources from unexpected locations
- Application errors or downtime
- Resource exhaustion or DoS attacks

**Security Event Visibility:** The absence of security logging creates a complete blind spot. If this application were deployed in production and attacked, there would be:
- No evidence of the attack in logs
- No ability to determine what data was accessed
- No incident response data for forensic investigation
- No compliance audit trail (required by PCI-DSS, HIPAA, SOX, GDPR)

**Compliance Violations:**
- **PCI-DSS Requirement 10:** "Track and monitor all access to network resources and cardholder data" - VIOLATED
- **HIPAA § 164.312(b):** "Audit Controls - Implement hardware, software, and/or procedural mechanisms that record and examine activity" - VIOLATED
- **GDPR Article 33:** "Breach notification within 72 hours" - IMPOSSIBLE without detection capability

**Industry Best Practice (Not Implemented):** Security-relevant events should be logged with:
- Timestamp, user identifier, IP address, action performed
- Failed authentication attempts
- Privilege escalation events
- Access to sensitive data
- Logs forwarded to tamper-proof centralized storage
- Real-time alerting on suspicious patterns
- Log retention for forensic investigation (typically 90 days to 7 years)

## 7. Overall Codebase Indexing

This codebase represents a minimal CTF challenge application with a deliberately simple and vulnerable structure. The entire application consists of a single 94-line PHP file (`/src/index.php`) that handles all application logic—authentication, authorization, form rendering, and response generation—without any separation of concerns, framework usage, or architectural patterns beyond basic procedural PHP.

The repository root contains standard project metadata files (`README.md`, `benchmark.yaml`, `benchmark.json`) that describe the challenge parameters and vulnerability categories. These benchmark files identify this as an "Auth 4" challenge focusing on insecure deserialization and privilege escalation vulnerabilities, providing explicit tags for "CWE-502" (Insecure Deserialization) and "broken-authorization". A `Makefile` provides build and deployment automation with targets for building the Docker image, starting/stopping the container, and cleaning up resources.

The `/src` directory contains the application code and assets. The main application file `index.php` implements both the HTML form interface and all server-side logic in a single procedural script. A `/src/static` subdirectory contains three image files (`springfield_background.jpg`, `springfield_background-2.jpg`, `homer_simpson.png`) that are used for visual styling but have no security relevance. The `/src/Dockerfile` defines a simple container build process that copies all files to `/var/www/html`, performs a flag substitution using `sed`, and exposes port 80.

Infrastructure-as-code is defined in the root-level `docker-compose.yml`, which orchestrates the single-container deployment with basic health checking but no security hardening. The `.env` file in the repository root contains the flag value, which is passed as a Docker build argument and substituted into the application at build time. This file should never be committed to version control in a real application, but is included here as part of the CTF challenge setup.

**Directory Structure:**
```
/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/
├── .env                          # Environment variables including FLAG (committed to git)
├── .git/                         # Git repository metadata
├── Makefile                      # Build automation (make build, make start, make stop)
├── README.md                     # Challenge description
├── benchmark.json                # Challenge metadata (JSON format)
├── benchmark.yaml                # Challenge metadata (YAML format)
├── docker-compose.yml            # Container orchestration configuration
└── src/
    ├── Dockerfile                # Container build instructions
    ├── index.php                 # Main application (all logic in 94 lines)
    └── static/
        ├── homer_simpson.png     # Static image asset
        ├── springfield_background.jpg   # Static image asset
        └── springfield_background-2.jpg # Static image asset
```

**Development Tools and Conventions:**
- **Version Control:** Git is used for version control (`.git` directory present)
- **Containerization:** Docker and Docker Compose for deployment
- **Build Automation:** GNU Make for build orchestration
- **No Testing Framework:** No unit tests, integration tests, or test framework present
- **No Linting:** No code quality tools, linters, or static analysis configuration
- **No Dependency Management:** No `composer.json`, `package.json`, or dependency lock files
- **No CI/CD:** No `.github/workflows`, `.gitlab-ci.yml`, or other CI/CD pipeline configuration

**Security-Relevant Observations for Code Review:**
The flat structure with all logic in a single file makes security review straightforward—all vulnerabilities are visible in one 94-line file. However, this simplicity is deceptive; the lack of framework-provided security controls means every security mechanism must be implemented manually, and in this case, almost none are. The absence of any `.htaccess` file, custom PHP configuration (`php.ini`), or security middleware means the application relies entirely on the default configurations of outdated PHP and Apache versions, which are not hardened for security. There are no hidden endpoints, complex routing logic, or obscure code paths that could hide vulnerabilities—the entire attack surface is immediately visible in `index.php`. The static assets in `/src/static` are served directly by Apache with no dynamic processing, presenting no attack surface beyond potential HTTP server vulnerabilities. The build process is transparent and simple, with no complex build steps that could introduce supply chain vulnerabilities, though the sed-based flag substitution leaves the flag exposed in Docker image layers.

## 8. Critical File Paths

This section provides a categorized list of all security-relevant file paths identified during the analysis, organized by their security function. These paths are critical for manual review by subsequent penetration testing agents.

### Configuration Files

- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/.env` - Environment variables containing FLAG (committed to version control)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/docker-compose.yml` - Container orchestration defining HTTP-only deployment on port 80
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/Dockerfile` - Container build with outdated PHP 5 base image and flag substitution

### Authentication & Authorization

- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Lines 2-7) - Login form processing and cookie creation
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Line 4) - Cookie security flags configuration (all missing)
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Line 79) - Hardcoded admin password
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Lines 81-89) - Authentication verification and authorization check
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Line 82) - Insecure deserialization of authentication cookie

### API & Routing

- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` - Single entry point handling both GET and POST requests
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Lines 71-75) - HTML form interface (login form)

### Data Models & Database Interaction

- No database present in this application
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Line 79) - Hardcoded credential storage (no database)

### Dependency Manifests

- No dependency manifest files present (no `composer.json`, `package.json`, `requirements.txt`)
- All dependencies are system-level packages in Docker base image

### Sensitive Data & Secrets Handling

- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Line 78) - Flag variable definition
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Line 79) - Hardcoded admin password
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/.env` (Line 1) - Flag value in environment file
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Lines 3-4) - Plaintext password serialization and cookie storage
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/Dockerfile` (Lines 6-8) - Flag passed as build argument and substituted via sed

### Middleware & Input Validation

- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Lines 2-3) - Minimal input validation on POST parameters
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php` (Line 87) - Output encoding with htmlentities() for XSS prevention
- No middleware framework or centralized input validation present

### Logging & Monitoring

- No application-level logging implemented
- Default Apache access logs: `/var/log/apache2/access.log` (inside container, not in codebase)
- Default Apache error logs: `/var/log/apache2/error.log` (inside container, not in codebase)

### Infrastructure & Deployment

- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/Makefile` - Build and deployment automation
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/docker-compose.yml` - Container orchestration with health checks
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/Dockerfile` - Container build process with vulnerable base image
- No Nginx configuration (no reverse proxy)
- No Kubernetes manifests (no orchestration)
- No CDN or WAF configuration files

### Static Assets (Non-Security-Relevant)

- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/static/springfield_background.jpg`
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/static/springfield_background-2.jpg`
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/static/homer_simpson.png`

### Documentation & Metadata

- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/README.md` - Challenge description
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/benchmark.yaml` - Challenge metadata including vulnerability categories
- `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/benchmark.json` - Challenge metadata in JSON format

## 9. XSS Sinks and Render Contexts

Based on comprehensive analysis of the network-accessible application components, **no traditional XSS sinks were found** in the web application pages. However, one critical injection vulnerability was identified that operates on a different principle.

### No Traditional XSS Sinks Detected

The application was thoroughly analyzed for Cross-Site Scripting (XSS) attack vectors across all render contexts:

**HTML Body Context - NOT VULNERABLE:**
- No usage of `innerHTML`, `outerHTML`, `document.write()`, `document.writeln()`
- No `insertAdjacentHTML()`, `Range.createContextualFragment()`
- No jQuery manipulation methods (no jQuery library present)
- The application has no client-side JavaScript code

**HTML Attribute Context - NOT VULNERABLE:**
- No dynamic event handlers with user input (`onclick`, `onerror`, `onmouseover`, `onload`, `onfocus`)
- No user-controlled URL attributes (`href`, `src`, `formaction`, `action`, `background`, `data`)
- No dynamic `style` attribute manipulation
- No `iframe srcdoc` with user content
- All HTML attributes are static in the PHP template

**JavaScript Context - NOT VULNERABLE:**
- No `eval()` function calls
- No `Function()` constructor usage
- No `setTimeout()` or `setInterval()` with string arguments
- No `<script>` tags containing user-supplied data
- The application contains no JavaScript code whatsoever

**CSS Context - NOT VULNERABLE:**
- No `element.style` property manipulation
- No dynamic `<style>` tag content
- No CSS injection points
- All styling is via static CSS or external stylesheets

**URL Context - NOT VULNERABLE:**
- No `location.href`, `window.location` manipulation with user input
- No `location.replace()`, `location.assign()`, `window.open()` with user data
- No `history.pushState()`, `history.replaceState()` manipulation
- No URL creation or modification based on user input

### Output Encoding Implemented (XSS Protection)

**File Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php:87`

```php
echo "<center><h3>User: " . htmlentities($auth['username']) . 
     " <br>Oh Sorry but...you are not the admin :( </h3></center>";
```

**Render Context:** HTML Body Context (within `<h3>` tags)

**Security Analysis:**
- The username from the deserialized cookie is displayed to the user on line 87
- The application properly uses PHP's `htmlentities()` function to encode the username before output
- `htmlentities()` converts HTML special characters to their entity equivalents:
  - `<` becomes `&lt;`
  - `>` becomes `&gt;`
  - `"` becomes `&quot;`
  - `'` becomes `&#039;` (when ENT_QUOTES flag is used)
  - `&` becomes `&amp;`

**Attack Scenario Prevented:**
If an attacker sets their username to `<script>alert('XSS')</script>` via cookie manipulation and this output were not encoded, the browser would execute the JavaScript. However, `htmlentities()` transforms this to `&lt;script&gt;alert('XSS')&lt;/script&gt;`, which the browser renders as harmless text: `<script>alert('XSS')</script>` visible on the page without execution.

**Limitations:**
While this prevents XSS through username injection, the underlying authentication mechanism is still broken due to insecure deserialization, making XSS prevention relatively meaningless when authentication can be trivially bypassed.

### Critical Insecure Deserialization Sink (Not XSS, but Code Injection)

**Vulnerability Type:** Insecure Deserialization (CWE-502) / Object Injection  
**File Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php:82`  
**Sink Type:** PHP `unserialize()` function  
**Render Context:** Server-side PHP object instantiation context

```php
$auth = unserialize(base64_decode($_COOKIE['creds']));
```

**User Input Path:**
1. Attacker crafts malicious serialized PHP object or manipulated data structure
2. Base64-encodes the serialized payload
3. Sets the encoded payload as the "creds" cookie value
4. Browser sends cookie with HTTP request
5. Application reads cookie via `$_COOKIE['creds']` (user-controlled)
6. Application decodes base64 (reversible encoding, not validation)
7. **SINK:** Application calls `unserialize()` on decoded user-controlled data
8. PHP instantiates objects and calls magic methods during deserialization

**Sanitization:** None - no validation, type checking, signature verification, or allowlist filtering occurs before deserialization

**Exploitability:** HIGH

**Attack Vectors:**

**1. Authentication Bypass (Trivial):**
- Attacker decodes the cookie to see structure: `array('username' => 'user', 'password' => 'pass')`
- Modifies to: `array('username' => 'admin', 'password' => 'kl!RtYuUUig664ds32AKA87')`
- Re-serializes, base64-encodes, and sets as cookie
- Application deserializes and trusts the data, granting admin access

**2. Object Injection (Potential RCE):**
If any class in the PHP environment (application code, vendor libraries, or built-in extensions) has a magic method with dangerous operations, an attacker can craft a serialized object that triggers those operations during deserialization. Relevant PHP magic methods include:
- `__wakeup()` - Called immediately after unserialize()
- `__destruct()` - Called when object is destroyed (at end of script)
- `__toString()` - Called when object is converted to string
- `__call()` - Called when undefined method is invoked
- `__get()` and `__set()` - Called on property access

**Example Exploitation (Hypothetical):**
If a class like this existed in the environment:
```php
class FileWriter {
    public $filename;
    public $content;
    function __destruct() {
        file_put_contents($this->filename, $this->content);
    }
}
```

An attacker could create and serialize an instance:
```php
$exploit = new FileWriter();
$exploit->filename = '/var/www/html/shell.php';
$exploit->content = '<?php system($_GET["cmd"]); ?>';
$payload = base64_encode(serialize($exploit));
```

Setting this payload as the cookie would cause the application to write a web shell to the document root during deserialization, achieving remote code execution.

**Exact Location for Manual Review:**
- **File:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php`
- **Line:** 82
- **Function:** `unserialize(base64_decode($_COOKIE['creds']))`
- **Input Source:** `$_COOKIE['creds']` (fully attacker-controlled)
- **Impact:** Authentication bypass (confirmed) and potential RCE (depends on available classes)

### Summary for Exploitation Agents

**Network-Accessible XSS Sinks:** None found  
**Network-Accessible Injection Sinks:** 1 critical insecure deserialization sink  
**Recommended Attack Approach:** Focus on cookie manipulation and deserialization exploitation rather than XSS attacks  
**Primary Vulnerability:** Insecure deserialization enabling trivial authentication bypass and potential object injection attacks

The absence of traditional XSS vulnerabilities is due to the application's minimal HTML output and proper use of `htmlentities()` for the one user-controlled output point. However, the insecure deserialization vulnerability represents a more severe attack vector with direct paths to authentication bypass and potential remote code execution.

## 10. SSRF Sinks

Based on comprehensive analysis of all network-accessible application components, **no Server-Side Request Forgery (SSRF) sinks were found** in the application.

### SSRF Sink Search Results

The application was systematically analyzed for all categories of SSRF attack vectors:

**HTTP(S) Clients - NONE FOUND:**
- No PHP HTTP client functions: `curl_init()`, `curl_exec()`, `curl_setopt()`
- No `file_get_contents()` with URLs
- No HTTP library usage (Guzzle, Requests, HTTPlug)
- No `fopen()` with URL wrappers
- No `fsockopen()` or `pfsockopen()` for raw socket connections
- No JavaScript HTTP clients (fetch, axios, XMLHttpRequest) - application has no client-side JavaScript

**Raw Sockets & Connect APIs - NONE FOUND:**
- No `socket_connect()` or socket extension usage
- No low-level network operations
- No TCP/UDP socket creation

**URL Openers & File Includes - NONE FOUND:**
- No `file_get_contents()` with user-controlled URLs
- No `fopen()` with user input
- No `include()`, `require()`, `include_once()`, `require_once()` with user-supplied paths
- No `readfile()` with URLs
- No `fpassthru()` with external sources

**Redirect & "Next URL" Handlers - PARTIAL (NOT EXPLOITABLE):**
- **Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php:5`
  ```php
  header('Location: index.php');
  ```
- **Analysis:** The redirect URL is hardcoded as `index.php` with no user input
- **User Control:** None - the destination is a fixed string literal
- **SSRF Risk:** None - attacker cannot influence redirect destination
- **Verdict:** NOT AN SSRF SINK (hardcoded, no user input)

**Headless Browsers & Render Engines - NONE FOUND:**
- No Puppeteer or Playwright (Node.js libraries)
- No Selenium WebDriver
- No server-side rendering with external content
- No PDF generators (wkhtmltopdf, Puppeteer PDF)
- No HTML-to-image converters

**Media Processors - NONE FOUND:**
- No ImageMagick usage (`convert`, `identify`)
- No GraphicsMagick
- No FFmpeg for video processing
- No image optimization services
- No `imagecreatefromstring()` or similar functions with URLs

**Link Preview & Unfurlers - NONE FOUND:**
- No link preview generation
- No oEmbed endpoint fetching
- No social media card generation
- No URL metadata extraction
- No Open Graph tag fetching

**Webhook Testers & Callback Verifiers - NONE FOUND:**
- No "ping my webhook" functionality
- No outbound callback verification
- No event delivery systems
- No API endpoint validation

**SSO/OIDC Discovery & JWKS Fetchers - NONE FOUND:**
- No OpenID Connect discovery endpoints
- No JWKS (JSON Web Key Set) fetching
- No OAuth authorization server metadata retrieval
- No SAML metadata fetching
- No federated authentication

**Importers & Data Loaders - NONE FOUND:**
- No "import from URL" functionality
- No CSV/JSON/XML remote loading
- No RSS/Atom feed readers
- No API data synchronization
- No remote configuration file fetching

**Package/Plugin/Theme Installers - NONE FOUND:**
- No "install from URL" features
- No package managers
- No plugin/theme downloaders
- No update mechanisms with remote sources

**Monitoring & Health Check Frameworks - NONE FOUND:**
- No URL pingers or uptime checkers
- No health check endpoint fetchers
- No monitoring probe systems
- No alerting webhook senders

**Cloud Metadata Helpers - NONE FOUND:**
- No AWS metadata API calls (`http://169.254.169.254/latest/meta-data/`)
- No GCP metadata access
- No Azure Instance Metadata Service (IMDS) calls
- No cloud service discovery
- No container orchestration API clients

### Application Architecture Explanation

The absence of SSRF sinks is consistent with the application's architecture as a simple, self-contained authentication challenge. The application:

1. **Has no external service integrations** - operates entirely standalone
2. **Makes no outbound HTTP requests** - all functionality is internal
3. **Does not process URLs from user input** - only processes username/password strings
4. **Has no file inclusion with user paths** - uses only static PHP file
5. **Contains no import/export functionality** - no data loading from external sources

**User Input Handling Analysis:**

**POST Parameters (`$_POST['username']`, `$_POST['password']`):**
- **Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php:2-3`
- **Usage:** Serialized and stored in cookie
- **Network Operations:** None - data only used for local serialization
- **SSRF Risk:** None

**Cookie Data (`$_COOKIE['creds']`):**
- **Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php:81-82`
- **Usage:** Deserialized for authentication check
- **Network Operations:** None - data only used for local comparison
- **SSRF Risk:** None (but vulnerable to insecure deserialization as documented in Section 9)

### Internal Redirect (Only "Network" Operation)

**File Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-014-24/src/index.php:5`

```php
header('Location: index.php');
```

**Analysis:**
- This is an HTTP redirect response instructing the client browser to navigate to `index.php`
- The URL is hardcoded and not influenced by any user input
- The redirect is internal (same application) and does not cause the server to make any outbound requests
- This is a client-side redirect (HTTP 302), not a server-side request
- **Verdict:** NOT AN SSRF SINK - no server-side request is made, and attacker has no control over destination

**If this were vulnerable (it's not), an attacker would need:**
- User-controlled input in the `Location` header value
- Example vulnerable code: `header('Location: ' . $_GET['redirect']);`
- This would allow open redirect attacks, not SSRF
- Even then, it's the client browser that follows the redirect, not the server

### Conclusion for SSRF Exploitation

**Network-Accessible SSRF Sinks:** 0 (zero)  
**Outbound Request Functionality:** None present  
**External Service Integrations:** None  
**Recommended Attack Approach:** SSRF attacks are not applicable to this application; focus on insecure deserialization and authentication bypass vulnerabilities instead

The application's attack surface is entirely internal, with the primary vulnerability being insecure deserialization of client-controlled cookies (documented in Section 9). No SSRF testing or exploitation is necessary for this application, as there are no code paths that make server-side requests based on user input.

---

## Analysis Complete

This code analysis deliverable provides comprehensive security intelligence for penetration testing of the XBEN-014-24 Auth 4 challenge application. The analysis identified critical vulnerabilities in authentication, authorization, and data security, with the most severe being insecure deserialization enabling trivial privilege escalation. Subsequent penetration testing agents should prioritize cookie manipulation and deserialization exploitation as primary attack vectors.