# SSRF Analysis Report

## 1. Executive Summary
- **Analysis Status:** Complete
- **Key Outcome:** ZERO SSRF vulnerabilities identified. This application has no server-side request forgery attack surface.
- **Purpose of this Document:** This report provides comprehensive analysis confirming that the application does not implement any mechanisms for making outbound HTTP requests, URL fetching, or external resource loading that could be exploited for SSRF attacks.

## 2. Dominant Vulnerability Patterns

### No SSRF Patterns Identified

After systematic analysis of all network-accessible endpoints and code paths, **NO SSRF vulnerability patterns were discovered**. The application architecture fundamentally lacks the components necessary for SSRF exploitation:

- **No HTTP Client Libraries**: The codebase contains no curl, file_get_contents, fopen with URLs, or similar mechanisms for making outbound HTTP requests
- **No URL Processing**: No endpoints accept or process URL parameters for external resource fetching
- **No Webhook/Callback Functionality**: No features for delivering webhooks or making callback requests to user-specified URLs
- **No SSO/OIDC Integration**: No authentication flows that fetch external metadata or JWKS endpoints
- **No Import/Preview Features**: No functionality to load external resources, generate link previews, or import data from URLs

**Architectural Context:** This is a deliberately simple CTF challenge focused on SQL injection exploitation. The application's scope is intentionally minimal: accept form data, store it in MySQL, and serve static files. This design inadvertently eliminates all SSRF attack vectors by not implementing any features requiring external network communication.

## 3. Strategic Intelligence for Exploitation

**Application Architecture:**
- **HTTP Client Library:** NONE - No HTTP client libraries are used in the application code
- **Network Request Pattern:** The application makes ZERO outbound HTTP requests. The only network connection is to the internal MySQL database container using a hardcoded hostname (`"db"`)
- **Request-Making Endpoints:** NONE - No endpoints exist that initiate server-side HTTP requests based on user input or any other trigger

**Internal Services:**
- **MySQL Database:** Accessible at `db:3306` (internal Docker network only), but connection parameters are hardcoded and cannot be influenced by user input
- **Docker Health Checks:** Use curl and mysqladmin but are infrastructure-level, not controlled by application code

**Why SSRF is Not Viable:**
1. The single backend endpoint (`/send.php`) only performs database INSERT/SELECT operations
2. No code paths involve `curl_exec()`, `file_get_contents()`, socket connections, or any URL-based resource loading
3. The redirect at line 67 of `send.php` uses a hardcoded value (`"index.html"`) with no user input
4. Static HTML pages contain no URL processing or external resource loading mechanisms

## 4. Systematic Analysis Results

### 4.1 HTTP(S) Client Analysis
**Status:** ❌ NOT FOUND

**Searched Functions:**
- `curl_init`, `curl_exec`, `curl_setopt`, `curl_multi_*`
- `file_get_contents()` with URL schemes
- `fopen()` with http:// or https:// wrappers
- `stream_context_create()` with URL options
- `Guzzle`, `Requests`, or other PHP HTTP libraries

**Finding:** ZERO instances in `/app/send.php` or any network-accessible code.

**Note:** The `curl` binary exists in the container but is only used in Docker health checks (`docker-compose.yml` line 28), which are infrastructure-level and not reachable through application requests.

**Verdict:** SAFE - No HTTP client attack surface

---

### 4.2 Raw Socket Analysis
**Status:** ❌ NOT FOUND

**Searched Functions:**
- `socket_create()`, `socket_connect()`
- `fsockopen()`, `pfsockopen()`
- `stream_socket_client()`

**Finding:** No socket operations exist in application code.

**Note:** `netcat` is used in `entrypoint.sh` for MySQL readiness check at container startup, but this is not triggered by or accessible through network requests.

**Verdict:** SAFE - No raw socket attack surface

---

### 4.3 URL Processing & Redirect Analysis
**Status:** ✅ ANALYZED - SAFE

**Code Location:** `/app/send.php` line 67
```php
header("Location: index.html");
```

**Analysis:**
- Redirect target is **hardcoded static string**
- No user input influences the Location header value
- No URL parameters like `?next=`, `?redirect=`, or `?returnUrl=` are processed
- Application does not read `$_GET` parameters anywhere

**Tested for:**
- Open redirect vulnerabilities
- Header injection via CRLF
- User-controlled redirect destinations

**Verdict:** SAFE - Redirect is not user-controllable

---

### 4.4 Webhook & Callback Analysis
**Status:** ❌ NOT FOUND

**Searched Features:**
- Webhook delivery endpoints
- Callback URL verification
- Event notification systems
- "Ping my webhook" testing tools

**Finding:** No webhook or callback functionality exists in the application.

**Verdict:** SAFE - No webhook attack surface

---

### 4.5 SSO/OIDC/OAuth Analysis
**Status:** ❌ NOT FOUND

**Searched Features:**
- OAuth client implementations
- OIDC discovery endpoint fetching
- JWKS (JSON Web Key Set) retrieval
- SAML metadata loading
- Authorization code/token endpoints

**Finding:** The application has NO authentication system (as documented in recon Section 3). The `signin.html` and `signup.html` pages are non-functional UI templates that submit to an external service (`formbold.com`).

**Verdict:** SAFE - No identity provider integration

---

### 4.6 Import/Fetch Features Analysis
**Status:** ❌ NOT FOUND

**Searched Features:**
- "Import from URL" functionality
- CSV/JSON/XML remote loading
- RSS/Atom feed readers
- API data synchronization
- File download from URL

**Finding:** The only data input mechanism is the HTML contact form via POST. No file upload, URL import, or external data loading features exist.

**Verdict:** SAFE - No import/fetch attack surface

---

### 4.7 Media Processing & Rendering Analysis
**Status:** ❌ NOT FOUND

**Searched Features:**
- ImageMagick, GD, FFmpeg
- PDF generators (wkhtmltopdf, Puppeteer PDF mode)
- Headless browsers (Puppeteer, Selenium, Playwright)
- Server-Side Rendering with external content fetching
- Link preview/unfurl functionality
- oEmbed endpoint processing

**Finding:** 
- No image processing libraries installed (`docker-php-ext-install mysqli` only)
- No PDF generation tools
- No headless browser automation
- Application serves pre-existing static images only

**Verdict:** SAFE - No media processing attack surface

---

### 4.8 Database Connection Analysis
**Status:** ✅ ANALYZED - SAFE

**Code Location:** `/app/send.php` lines 4-9
```php
$servername = "db";  // HARDCODED
$username = "challenge";
$password = "challenge";
$dbname = "challenge";

$conn = new mysqli($servername, $username, $password, $dbname);
```

**Analysis:**
- Database hostname is a **hardcoded constant** (`"db"`)
- No user input can influence `$servername`, port, or any connection parameters
- No environment variable injection or query parameter processing
- All mysqli connection parameters are static

**Tested for:**
- User-controlled hostname redirection
- Port manipulation
- Protocol switching

**Verdict:** SAFE - Connection target cannot be manipulated

---

### 4.9 Cloud Metadata & Service Discovery Analysis
**Status:** ❌ NOT APPLICABLE

**Searched Features:**
- AWS/GCP/Azure SDK usage
- Instance metadata API calls (169.254.169.254)
- Kubernetes API client
- Docker socket access
- Cloud provider service discovery

**Finding:** Application is designed for local Docker deployment with no cloud-specific integrations.

**Verdict:** SAFE - No cloud metadata attack surface

---

## 5. Secure by Design: Validated Components

All network-accessible components were analyzed and confirmed to have no SSRF attack surface:

| Component/Flow | Endpoint/File Location | Architecture Pattern | Verdict |
|---|---|---|---|
| Contact Form Handler | `/send.php` POST | Database INSERT/SELECT only, no outbound requests | SAFE |
| Static Page Serving | `/index.html`, `/signin.html`, `/signup.html` | Pure static HTML/CSS/JS, no server-side processing | SAFE |
| JavaScript Bundle | `/bundle.js` | Client-side Alpine.js framework, no server-side execution | SAFE |
| Redirect Mechanism | `/send.php:67` | Hardcoded `Location: index.html`, no user input | SAFE |
| Database Connection | `/send.php:4-9` | Hardcoded `mysqli` connection to `"db"`, no parameter injection | SAFE |
| Docker Health Checks | `docker-compose.yml` | Infrastructure-level curl/mysqladmin, not application-triggered | SAFE |

---

## 6. Analysis Methodology Applied

The following comprehensive checks were performed per the SSRF methodology:

### ✅ 1. HTTP Client Usage Patterns
- **Checked:** All endpoints for URL parameters, callback URLs, webhook URLs, file paths
- **Result:** No endpoints accept URL-based parameters
- **Checked:** HTTP client libraries (requests, urllib, axios, fetch, HttpClient, curl, Guzzle)
- **Result:** NONE found in application code

### ✅ 2. Protocol and Scheme Validation
- **Checked:** Whether application validates URL protocols
- **Result:** N/A - application does not process URLs

### ✅ 3. Hostname and IP Address Validation
- **Checked:** Whether internal IP ranges are blocked
- **Result:** N/A - application does not make network requests based on user input

### ✅ 4. Port Restriction and Service Access Controls
- **Checked:** Whether port restrictions exist for outbound requests
- **Result:** N/A - no outbound request functionality exists

### ✅ 5. URL Parsing and Validation Bypass Techniques
- **Checked:** URL encoding, redirects, malformed URLs, IPv6, IDN
- **Result:** N/A - no URL parsing in application code

### ✅ 6. Request Modification and Headers
- **Checked:** Whether sensitive headers are stripped, custom header injection
- **Result:** N/A - no request proxying or header manipulation

### ✅ 7. Response Handling and Information Disclosure
- **Checked:** Whether responses are returned to user (blind vs non-blind SSRF)
- **Result:** N/A - no external requests made

---

## 7. Conclusion

**SSRF Attack Surface: ZERO**

This application's functionality is intentionally limited to:
1. Accepting form submissions via POST to `/send.php`
2. Storing data in internal MySQL database
3. Serving static HTML/CSS/JavaScript files

**No code paths involve:**
- Server-side outbound HTTP requests
- URL fetching or external resource loading
- Network socket operations influenced by user input
- Webhook delivery or callback mechanisms
- SSO/OIDC metadata retrieval
- Import from URL features

**Strategic Recommendation:** SSRF testing should **not be performed** on this target. Penetration testing resources should be allocated to the CRITICAL SQL injection vulnerability at `/send.php:50`, which is the intended exploitation path for this CTF challenge and provides direct database access for flag extraction.

**Confidence Level:** HIGH - The absence of SSRF attack surface is definitively established through comprehensive code analysis covering all potential SSRF sink categories.

---

## 8. Files Analyzed

**Application Code:**
- `/app/send.php` (68 lines - primary backend endpoint)
- `/app/index.html` (918 lines - contact form UI)
- `/app/signin.html` (non-functional auth UI)
- `/app/signup.html` (non-functional auth UI)
- `/app/bundle.js` (744KB - Alpine.js framework)

**Infrastructure:**
- `docker-compose.yml` (orchestration with health checks)
- `/app/Dockerfile` (application container definition)
- `/mysql/Dockerfile` (database container definition)
- `/app/entrypoint.sh` (startup script with netcat usage)

**Total Analysis Coverage:** 100% of network-accessible application code paths
