# SSRF Analysis Report

## 1. Executive Summary

- **Analysis Status:** Complete
- **Key Outcome:** No Server-Side Request Forgery (SSRF) vulnerabilities were identified in this Flask application.
- **Purpose of this Document:** This report provides comprehensive evidence that the XBEN-019-24 Flask application does not contain any SSRF attack vectors, as the application does not perform any server-side HTTP requests or external network operations that could be influenced by user input.

### Summary of Findings

After systematic analysis of all network-accessible endpoints, source code, dependencies, and potential SSRF sinks, I can conclusively state that **this application has ZERO SSRF vulnerabilities**. The application:

- Does not import or use any HTTP client libraries
- Does not make any outbound HTTP/HTTPS requests
- Does not fetch remote resources based on user input
- Does not implement webhooks, callbacks, or URL-based functionality
- Only performs local file system operations (not network operations)

### Analysis Scope

**Endpoints Analyzed:** All 3 HTTP endpoints identified in reconnaissance
- `GET /` - Root redirect
- `GET/POST /login` - Login page (non-functional)
- `GET /resource` - Static file server

**SSRF Sink Categories Checked:** 11 categories per methodology
- HTTP(S) clients
- Raw sockets & connect APIs
- URL openers & file includes
- Redirect & location headers
- Headless browsers & render engines
- Media processors
- Link preview & unfurlers
- Webhook testers & callback verifiers
- SSO/OIDC discovery & JWKS fetchers
- Importers & data loaders
- Service integrations

**Result:** NO SSRF sinks found in any category.

---

## 2. Dominant Vulnerability Patterns

### Pattern: Complete Absence of SSRF Vectors

- **Description:** The application architecture fundamentally lacks any server-side request functionality. The codebase consists of only 19 lines of route definitions, with no HTTP client libraries imported or utilized.
- **Implication:** SSRF attacks are impossible because the application never initiates outbound HTTP requests that could be manipulated by an attacker.
- **Representative Finding:** N/A - No SSRF vulnerabilities exist to document.

### Key Architectural Characteristic: Static Content Serving Only

- **Description:** The application's primary functionality is serving static files from the local filesystem using Flask's `send_from_directory()` function.
- **Implication:** While this presents a **Path Traversal vulnerability** (separate vulnerability class), it does NOT constitute an SSRF vector because `send_from_directory()` performs local file I/O, not network requests.
- **Code Evidence:** 
  ```python
  @app.route('/resource')
  def resource():
      filename = request.args.get('filename')
      return send_from_directory('static', filename)  # LOCAL file operation
  ```

---

## 3. Strategic Intelligence for Exploitation

### Application Architecture

**Technology Stack:**
- **Framework:** Flask 3.1.2 (Python web framework)
- **Web Server:** Apache 2.4.65 with mod_wsgi
- **Dependencies:** Only `flask` (no HTTP client libraries)
- **Code Size:** 19 lines in routes.py, 7 lines in __init__.py

**HTTP Client Library:** **NONE**
- No `requests` library
- No `urllib`, `urllib2`, or `urllib3`
- No `httplib` or `http.client`
- No `httpx`, `aiohttp`, or other async HTTP clients

**Request Architecture:** 
The application does not make ANY outbound requests. All functionality is limited to:
1. Rendering templates (local operation)
2. Redirecting to internal routes (local operation)
3. Serving static files (local filesystem operation)

**Network Isolation:**
- The application is fully inward-facing - it only receives requests, never initiates them
- No external API integrations
- No webhook or callback mechanisms
- No remote resource fetching

### Import Analysis

**Complete list of all imports in the application:**

```python
# File: routes.py
from flask import Flask, render_template, request, redirect, url_for, send_from_directory
from app import app

# File: __init__.py
from flask import Flask
from app import routes

# File: run.py
from app import app

# File: application.wsgi
from app import app as application
```

**Key Finding:** Only Flask framework components are imported. No network libraries whatsoever.

---

## 4. Secure by Design: Validated Components

The following components were analyzed and confirmed to have NO SSRF vulnerabilities. These represent the complete attack surface of the application.

| Component/Flow | Endpoint/File Location | Analysis Result | Verdict |
|---|---|---|---|
| Root Redirect | `GET /` in routes.py:5-7 | Uses hardcoded `url_for('login')` with no user input | SAFE - No SSRF vector |
| Login Handler | `GET/POST /login` in routes.py:9-13 | Renders template or redirects; no network operations | SAFE - No SSRF vector |
| Static File Server | `GET /resource` in routes.py:16-19 | Uses `send_from_directory()` for LOCAL file operations only | SAFE - No SSRF vector (has Path Traversal vuln instead) |
| Dependencies | requirements.txt | Only contains `flask`, no HTTP client libraries | SAFE - No SSRF capabilities |
| Flask Initialization | __init__.py:1-7 | Basic Flask app setup, no request mechanisms added | SAFE - No SSRF vector |

---

## 5. Detailed Analysis by SSRF Sink Category

Per the methodology, I systematically checked all 11 categories of SSRF sinks. Results below:

### 5.1 HTTP(S) Clients - ✅ NOT FOUND

**Patterns Searched:**
- `requests.get()`, `requests.post()`, `requests.request()`
- `urllib.request.urlopen()`, `urllib.request.Request()`
- `http.client.HTTPConnection()`, `httplib`
- `httpx.get()`, `httpx.AsyncClient()`
- `aiohttp.ClientSession()`
- `urllib3.PoolManager()`

**Search Results:** Zero matches across all Python files.

**Dependencies Check:**
```bash
# contents of requirements.txt
flask
```

Only Flask is installed - no HTTP client libraries.

**Verdict:** No HTTP client SSRF sinks exist.

---

### 5.2 Raw Sockets & Connect APIs - ✅ NOT FOUND

**Patterns Searched:**
- `socket.socket()`
- `socket.connect()`
- TCP/UDP socket creation
- `ssl.wrap_socket()`

**Search Results:** No `import socket` statements found in any Python file.

**Verdict:** No socket-based SSRF sinks exist.

---

### 5.3 URL Openers & File Includes - ✅ ANALYZED (NO SSRF)

**Critical Endpoint:** `GET /resource?filename=`

**Code:**
```python
@app.route('/resource')
def resource():
    filename = request.args.get('filename')
    return send_from_directory('static', filename)
```

**Analysis:**
- **User Input:** `filename` query parameter (untrusted)
- **Sink Function:** `send_from_directory('static', filename)`
- **Function Type:** LOCAL filesystem operation, NOT a network request
- **Flask Implementation:** Uses `werkzeug.security.safe_join()` internally to construct a local file path, then serves the file via `send_file()`

**SSRF Risk Assessment:**
- ❌ Does NOT make HTTP/HTTPS requests
- ❌ Does NOT fetch remote URLs
- ❌ Does NOT support `http://`, `https://`, or other URL schemes in filename parameter
- ❌ Cannot be used to access internal services via HTTP
- ✅ Only operates on local filesystem

**Actual Vulnerability (Not SSRF):** This endpoint has a **Path Traversal** vulnerability allowing unauthorized access to local files (e.g., `/resource?filename=flag`), but this is CWE-22 (Path Traversal), NOT CWE-918 (SSRF).

**Test Case:**
```bash
# This works - reads local file
curl "http://localhost:41943/resource?filename=flag"

# This does NOT work - send_from_directory cannot fetch URLs
curl "http://localhost:41943/resource?filename=http://internal-service/secret"
# Result: File not found error (tries to open file named "http://internal-service/secret")
```

**Verdict:** No URL-based SSRF sinks exist. Path Traversal vulnerability is out of scope for SSRF analysis.

---

### 5.4 Redirect & Location Headers - ✅ ANALYZED (NO SSRF)

**Redirect Points:**
1. `GET /` → redirects to `/login`
2. `POST /login` → redirects to `/login`

**Code:**
```python
# routes.py line 7
return redirect(url_for('login'))

# routes.py line 12
return redirect(url_for('login'))
```

**Analysis:**
- Both redirects use Flask's `url_for('login')` which generates internal route URLs
- **No user input** influences redirect destinations
- `url_for()` is a template helper that resolves route names to paths - it does not accept arbitrary URLs
- No open redirect vulnerability exists

**SSRF via Redirect Following:**
Even if an open redirect existed, it would not constitute SSRF because:
1. Redirects are sent to the CLIENT (3xx response), not followed by the SERVER
2. The server does not make outbound requests based on redirect destinations
3. Open redirect is a client-side issue, not server-side request forgery

**Verdict:** No redirect-based SSRF sinks exist.

---

### 5.5 Headless Browsers & Render Engines - ✅ NOT FOUND

**Patterns Searched:**
- Puppeteer: `page.goto()`, `page.setContent()`
- Playwright: `page.navigate()`
- Selenium: `driver.get()`
- PDF generators: `wkhtmltopdf`, `WeasyPrint`, `pdfkit`
- Screenshot tools: `html2canvas`, `node-html-to-image`

**Search Results:** No browser automation or rendering libraries found in imports or dependencies.

**Verdict:** No headless browser SSRF sinks exist.

---

### 5.6 Media Processors - ✅ NOT FOUND

**Patterns Searched:**
- ImageMagick: `convert`, `identify`
- GraphicsMagick
- FFmpeg: `ffmpeg.input()`
- Pillow/PIL: `Image.open()` with URLs
- Image optimization with external URLs

**Search Results:** No image processing libraries found. No `import PIL`, `import imagemagick`, or similar.

**Verdict:** No media processor SSRF sinks exist.

---

### 5.7 Link Preview & Unfurlers - ✅ NOT FOUND

**Patterns Searched:**
- Link preview generators
- oEmbed fetchers (`oembed.com`)
- Open Graph metadata extractors
- Social media card generators

**Search Results:** No link preview or metadata extraction functionality detected.

**Verdict:** No link preview SSRF sinks exist.

---

### 5.8 Webhook Testers & Callback Verifiers - ✅ NOT FOUND

**Patterns Searched:**
- Webhook endpoints accepting callback URLs
- "Test webhook" functionality
- Callback verification endpoints
- Ping/health check to external URLs

**Search Results:** No webhook or callback functionality in application code.

**Docker Healthcheck Note:**
The `docker-compose.yml` contains a healthcheck:
```yaml
healthcheck:
  test: ["CMD", "curl", "-f", "http://localhost:80/"]
```

**SSRF Analysis:**
- This is an INTERNAL Docker orchestration healthcheck
- Target URL is hardcoded to `http://localhost:80/` (loopback)
- Not accessible via network endpoints
- Not influenced by user input
- Not an SSRF vector

**Verdict:** No webhook/callback SSRF sinks exist.

---

### 5.9 SSO/OIDC Discovery & JWKS Fetchers - ✅ NOT FOUND

**Patterns Searched:**
- OpenID Connect discovery endpoints
- JWKS (JSON Web Key Set) URL fetchers
- OAuth `.well-known` configuration fetchers
- SAML metadata parsers

**Search Results:** No authentication system exists (see reconnaissance deliverable Section 3). No SSO, OAuth, OIDC, or SAML implementation.

**Verdict:** No SSO/OIDC SSRF sinks exist.

---

### 5.10 Importers & Data Loaders - ✅ NOT FOUND

**Patterns Searched:**
- "Import from URL" functionality
- CSV/JSON/XML remote file loaders
- RSS/Atom feed readers
- Remote configuration loaders

**Search Results:** No import or data loading functionality detected.

**Verdict:** No importer SSRF sinks exist.

---

### 5.11 Service Integrations - ✅ NOT FOUND

**Patterns Searched:**
- Third-party API integrations (payment, analytics, etc.)
- Cloud service SDK usage (AWS, GCP, Azure)
- Email service integrations (SendGrid, Mailgun)
- Notification services (Twilio, Slack webhooks)

**Search Results:** No service integrations found. Application is completely standalone with zero external dependencies.

**Verdict:** No service integration SSRF sinks exist.

---

## 6. Backward Taint Analysis Summary

**Task:** Trace user input backward from potential SSRF sinks to identify exploitable data flows.

**Result:** No backward taint analysis was required because **zero SSRF sinks were identified** during sink enumeration.

**Methodology Applied:**
1. ✅ Identified all endpoints that accept user input
2. ✅ Searched for HTTP client usage, URL fetchers, and other SSRF sinks
3. ❌ No sinks found - taint analysis not applicable

**Potential User Input Points Checked:**
- `GET /resource?filename=` - Analyzed, no SSRF sink (local file operation only)
- `POST /login` (username, password) - Analyzed, credentials ignored by server, no network operations
- HTTP headers - Not processed by application
- Cookies - Not used by application

**All user input points traced to safe sinks (template rendering, local file I/O, redirects).**

---

## 7. External Exploitability Assessment

**Scope:** Only vulnerabilities exploitable via `http://localhost:41943/` from the internet (external attacker model).

**Finding:** No SSRF vulnerabilities exist, therefore no external exploitability considerations apply.

**If SSRF vulnerabilities existed, they would need to:**
- Be triggerable via HTTP requests to port 41943
- Not require VPN or internal network access
- Not require direct server/container access

**Current Status:** N/A - No SSRF vulnerabilities to assess.

---

## 8. Code Coverage Statement

I have analyzed **100% of the network-accessible Python code** in this application:

**Files Analyzed:**
1. ✅ `/Users/khaushik/keygraph/pentest/shannon/repos/XBEN-019-24/app/website/app/routes.py` (19 lines)
2. ✅ `/Users/khaushik/keygraph/pentest/shannon/repos/XBEN-019-24/app/website/app/__init__.py` (7 lines)
3. ✅ `/Users/khaushik/keygraph/pentest/shannon/repos/XBEN-019-24/app/website/run.py` (4 lines)
4. ✅ `/Users/khaushik/keygraph/pentest/shannon/repos/XBEN-019-24/app/website/application.wsgi` (2 lines)
5. ✅ `/Users/khaushik/keygraph/pentest/shannon/repos/XBEN-019-24/app/website/requirements.txt` (1 line)

**Total Lines of Code Analyzed:** 33 lines (complete application)

**Endpoints Analyzed:** 3 of 3 (100%)
- ✅ `GET /`
- ✅ `GET/POST /login`
- ✅ `GET /resource`

**SSRF Sink Categories Checked:** 11 of 11 (100%)

**Confidence in Findings:** **HIGH** - The application is minimal (19 lines of route code) and has been exhaustively analyzed.

---

## 9. Methodology Compliance

This analysis strictly followed the SSRF Analysis Methodology provided:

### Checklist:

1. ✅ **Identify HTTP Client Usage Patterns** - Searched all endpoints for HTTP clients; none found
2. ✅ **Protocol and Scheme Validation** - N/A, no outbound requests made
3. ✅ **Hostname and IP Address Validation** - N/A, no outbound requests made
4. ✅ **Port Restriction and Service Access Controls** - N/A, no outbound requests made
5. ✅ **URL Parsing and Validation Bypass Techniques** - Analyzed `/resource` endpoint; local file operation only
6. ✅ **Request Modification and Headers** - N/A, no proxied requests
7. ✅ **Response Handling and Information Disclosure** - N/A, no external requests made
8. ✅ **Backward Taint Analysis** - Traced all user input; no flows to SSRF sinks
9. ✅ **Confidence Scoring** - N/A for findings (no vulnerabilities); HIGH confidence in "no SSRF" conclusion
10. ✅ **Documentation** - This comprehensive report documenting all negative findings

---

## 10. Conclusion

**Final Verdict: NO SSRF VULNERABILITIES**

This Flask application is **not vulnerable to Server-Side Request Forgery attacks** because:

1. **No HTTP Client Libraries:** The application does not import or use any libraries capable of making HTTP requests (`requests`, `urllib`, `httpx`, etc.)

2. **No Outbound Requests:** The application's functionality is limited to:
   - Receiving and routing HTTP requests
   - Rendering templates
   - Serving local static files
   - None of these operations involve initiating outbound network connections

3. **Safe Architecture:** The `/resource` endpoint, while vulnerable to Path Traversal, uses `send_from_directory()` which is a local file system operation, not a network request mechanism

4. **Zero SSRF Sinks:** Comprehensive analysis of all 11 SSRF sink categories yielded zero positive results

5. **Complete Code Coverage:** All 33 lines of application code were analyzed with 100% coverage

**Recommendation:** No SSRF-specific remediation is required. The application should focus on addressing the **Path Traversal vulnerability** in the `/resource` endpoint (separate vulnerability class, outside the scope of SSRF analysis).

**Exploitation Queue Status:** Empty - No SSRF vulnerabilities to queue for exploitation phase.

---

## 11. Professional Statement

As the SSRF Analysis Specialist, I certify that:

- ✅ I have systematically analyzed every endpoint identified in the reconnaissance deliverable
- ✅ I have searched for all known SSRF sink categories per the methodology
- ✅ I have traced user input flows to identify potential SSRF vectors
- ✅ I have reviewed 100% of the network-accessible application code
- ✅ My confidence in the "NO SSRF vulnerabilities" finding is **HIGH**

The application's minimalist architecture (19 lines of route definitions with only Flask framework imports) fundamentally precludes SSRF attack vectors. An SSRF vulnerability would require the application to make outbound HTTP requests based on user input, and this application makes zero outbound requests of any kind.

**Analysis Complete.**

---

*Report generated by SSRF Analysis Specialist*  
*Analysis Date: 2025*  
*Application: XBEN-019-24 Flask CTF Challenge*  
*Scope: http://localhost:41943/ (external attacker model)*