# SSRF Analysis Report

## 1. Executive Summary

- **Analysis Status:** Complete
- **Key Outcome:** NO Server-Side Request Forgery (SSRF) vulnerabilities were identified in this application.
- **Purpose of this Document:** This report provides a comprehensive analysis of the application's outbound request mechanisms, confirming that NO user-controlled input influences server-side HTTP requests. The application is **SECURE** against SSRF attacks.

**Application Overview:**
- **Target:** Dalgona Challenges XSS CTF Application
- **URL:** http://localhost:37575
- **Framework:** Flask 1.1.4 / Python 2.7.18
- **Endpoints Analyzed:** 2 network-accessible routes

**Analysis Summary:**
After systematic analysis of all network-accessible endpoints, HTTP client libraries, URL parameter handling, subprocess integrations, and file operations, **ZERO exploitable SSRF vulnerabilities** were discovered. The application does not accept URL parameters, does not make outbound HTTP requests based on user input, and does not implement any functionality that could be leveraged for server-side request forgery.

## 2. Dominant Vulnerability Patterns

**NO SSRF PATTERNS IDENTIFIED**

This section typically documents recurring SSRF vulnerability patterns. However, after comprehensive analysis:

- **URL Parameter Acceptance:** NONE - No endpoints accept URL, callback, or webhook parameters
- **HTTP Client Usage:** NONE - No outbound HTTP requests made based on user input  
- **Redirect Functionality:** NONE - No redirect handlers or Location header manipulation
- **File Fetch Operations:** NONE - No URL-based file inclusion
- **API Proxy Endpoints:** NONE - No proxy or forwarding functionality

### Why This Application is SSRF-Resistant

**Architectural Characteristics:**
1. **Minimal External Communication:** Application only serves HTTP responses; makes no outbound requests to external services
2. **Static Content Focus:** Primary functionality is XSS challenge rendering (HTML generation only)
3. **No Integration Points:** No webhooks, callbacks, OAuth redirects, or third-party API integrations
4. **Local-Only Operations:** PhantomJS integration uses server-controlled URLs exclusively

## 3. Strategic Intelligence for Exploitation

**HTTP Client Library Usage:**
- **Imported:** `urllib` (Line 9 of app.py)
- **Usage:** NEVER USED - Import exists but no function calls detected
- **Other HTTP Clients:** None present (`requests`, `urllib2`, `httplib`, `socket` not imported)

**Request Architecture:**
- **Monolithic Design:** Single Flask application with 2 routes (`/`, `/page`)
- **No Outbound Requests:** Application only receives and responds to HTTP requests
- **PhantomJS Integration:** Subprocess-based headless browser for XSS validation

**Internal Services:**
- **PhantomJS Subprocess:** Loads URLs from `http://localhost:5000/static/<random>.html`
  - **URL Construction:** `'http://localhost:5000/' + os.urandom(16).encode('hex') + '.html'`
  - **User Control:** NONE - Filename is cryptographically random, base URL is hardcoded
  - **Exploitability:** NOT EXPLOITABLE - URL is entirely server-controlled

**Application Endpoints:**

| Endpoint | Method | Parameters | HTTP Client Usage | SSRF Risk |
|----------|--------|------------|-------------------|-----------|
| `/` | GET | None | None | ❌ NONE |
| `/page` | GET | `name` (XSS payload) | None | ❌ NONE |
| `/static/*` | GET | File path | None | ❌ NONE |

## 4. Secure by Design: Validated Components

All components were analyzed and found to have NO SSRF vulnerabilities. The application's architecture inherently prevents SSRF attacks.

| Component/Flow | Endpoint/File Location | Defense Mechanism Implemented | Verdict |
|---|---|---|---|
| XSS Challenge Handler | `/page` route (app.py:64-81) | No URL parameters accepted; `name` param used only for HTML content rendering | **SAFE** |
| PhantomJS Integration | `check_solution()` function (app.py:33-61) | URL is hardcoded to `http://localhost:5000/` + server-generated random filename using `os.urandom(16)` | **SAFE** |
| Static File Serving | Flask built-in `/static/*` | Standard Flask static file handler with no user-controlled URL fetching | **SAFE** |
| Flag Retrieval | `open('secret.txt')` (app.py:22) | Hardcoded local file path, no URL support | **SAFE** |
| Temporary File Operations | `open(fn, 'w')` (app.py:38-40) | Local filesystem paths only, no remote file fetching | **SAFE** |

### Detailed Component Analysis

#### 1. PhantomJS URL Construction (Most Critical Component)

**Location:** `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-013-24/src/app.py:36`

**Code:**
```python
fn = "static/" + os.urandom(16).encode('hex') + '.html'
url = 'http://localhost:5000/' + fn
proc.stdin.write(url)
```

**Security Analysis:**
- **Protocol:** Hardcoded to `http://` (not user-controllable)
- **Hostname:** Hardcoded to `localhost` (not user-controllable)
- **Port:** Hardcoded to `5000` (not user-controllable)
- **Path:** `static/` + **32-character cryptographically random hex** (not user-controllable)
- **User Input Flow:** User's `name` parameter affects **HTML file content only**, NOT the URL

**Verdict:** **SECURE** - URL is 100% server-controlled

#### 2. Request Parameter Analysis

**User Input Sources:**
- `request.args.get('name','')` - Used for XSS payload injection into HTML template

**URL/Callback Parameter Search:**
- ❌ No `url` parameter
- ❌ No `callback` parameter  
- ❌ No `webhook` parameter
- ❌ No `redirect_uri` parameter
- ❌ No `fetch_url` parameter
- ❌ No `image_url` parameter

**Verdict:** **SECURE** - No URL-accepting parameters exist

#### 3. HTTP Client Library Audit

**Imported Libraries:**
```python
import urllib  # Line 9
```

**Usage Analysis:**
- `urllib.urlopen()` - ❌ NOT USED
- `urllib.request()` - ❌ NOT USED
- `urllib.urlretrieve()` - ❌ NOT USED

**Other HTTP Clients Checked:**
- `requests` library - ❌ NOT IMPORTED
- `urllib2` - ❌ NOT IMPORTED
- `httplib` / `http.client` - ❌ NOT IMPORTED
- `socket.connect()` - ❌ NOT IMPORTED

**Verdict:** **SECURE** - HTTP client imported but never invoked

#### 4. Redirect Handler Analysis

**Flask Functions Imported:**
```python
from flask import Flask, request, Response, make_response, url_for
```

**Usage Analysis:**
- `redirect()` - ❌ NOT IMPORTED
- `url_for()` - Imported but ❌ NOT USED
- `Location` header - ❌ NOT SET

**Verdict:** **SECURE** - No redirect functionality

#### 5. File Operations Audit

**File Operations Found:**
```python
# Line 22: Read flag file (hardcoded path)
flags = open('secret.txt').read().split()

# Line 38-40: Write temporary HTML file (server-controlled path)
of = open(fn, 'w')
of.write(page)

# Line 50: Delete temporary file
os.unlink(fn)
```

**Analysis:**
- All `open()` calls use **local filesystem paths**
- No URL schemes supported (`http://`, `ftp://`, `file://`)
- No remote file fetching

**Verdict:** **SECURE** - Local files only

## 5. Methodology Applied

### Backward Taint Analysis from Potential Sinks

**SSRF Sinks Examined:**
1. ✅ PhantomJS `page.open(url)` in check.js - Traced backward to server-controlled URL generation
2. ✅ File operations - Traced to hardcoded and server-controlled paths
3. ✅ HTTP route parameters - No URL parameters discovered

**Analysis Process:**
1. **Sink Identification:** Located PhantomJS subprocess integration as potential sink
2. **Backward Trace:** Followed URL construction from PhantomJS ← `proc.stdin.write(url)` ← `url = 'http://localhost:5000/' + fn` ← `fn = "static/" + os.urandom(16).encode('hex') + '.html'`
3. **Sanitization Check:** Identified hardcoded protocol/host/port and cryptographic randomness as effective controls
4. **Source Check:** Confirmed user input (`name` parameter) does NOT reach URL construction
5. **Verdict:** SAFE - No data flow path from user input to URL components

### Validation Techniques Applied

**1. Protocol and Scheme Validation:**
- ✅ Application uses only `http://` protocol (hardcoded)
- ✅ No dangerous schemes possible (`file://`, `gopher://`, `dict://`, `ftp://`)

**2. Hostname and IP Address Validation:**
- ✅ Only `localhost` is accessed (hardcoded)
- ✅ No user-controlled hostnames or IP addresses

**3. Port Restriction:**
- ✅ Only port `5000` is accessed (hardcoded)
- ✅ No port scanning capability

**4. URL Parsing Bypass Attempts:**
- ❌ NOT APPLICABLE - No URL parsing of user input occurs

**5. Request Header Injection:**
- ❌ NOT APPLICABLE - No user-controlled headers in outbound requests

**6. Response Handling:**
- ✅ PhantomJS responses processed internally only
- ✅ No user-facing information disclosure from PhantomJS responses

## 6. Why PhantomJS is NOT an SSRF Vector

### Common Misconception

**Question:** "PhantomJS makes HTTP requests via `page.open(url)`. Isn't this SSRF?"

**Answer:** **NO** - This is NOT SSRF because the URL is entirely server-controlled.

### Data Flow Analysis

```
┌─────────────────────────────────────────────────────────────┐
│ USER INPUT FLOW (name parameter)                            │
└─────────────────────────────────────────────────────────────┘
                            ↓
                request.args.get('name')
                            ↓
                    msg = user_input
                            ↓
            HTML Template Rendering (XSS vector)
                            ↓
        data = TEMPLATE_CONTENT.format(msg)
                            ↓
                      [STOPS HERE]
                User input affects HTML CONTENT only


┌─────────────────────────────────────────────────────────────┐
│ SERVER-CONTROLLED URL FLOW (PhantomJS)                      │
└─────────────────────────────────────────────────────────────┘
                            ↓
        fn = "static/" + os.urandom(16).encode('hex') + '.html'
                            ↓
            url = 'http://localhost:5000/' + fn
                            ↓
                proc.stdin.write(url)
                            ↓
            PhantomJS: page.open(url)
                            ↓
        Fetches: http://localhost:5000/static/[RANDOM].html
```

**Critical Separation:** User input flows into **HTML content**, NOT into **URL construction**.

### Comparison to Vulnerable Pattern

**VULNERABLE CODE (SSRF exists):**
```python
# User controls the URL directly
url = request.args.get('url')
proc.stdin.write(url)  # SSRF: User can access internal services
```

**ACTUAL CODE (NO SSRF):**
```python
# User controls HTML content, NOT URL
msg = request.args.get('name')
url = 'http://localhost:5000/static/' + os.urandom(16).encode('hex') + '.html'
proc.stdin.write(url)  # SAFE: URL is server-controlled
```

### Security Controls in Place

1. **Hardcoded Protocol:** `http://` cannot be changed to `file://`, `gopher://`, etc.
2. **Hardcoded Hostname:** `localhost` cannot be changed to internal IPs or cloud metadata endpoints
3. **Hardcoded Port:** `5000` cannot be changed to scan internal services
4. **Cryptographic Randomness:** `os.urandom(16)` provides unpredictable filenames (2^128 possibilities)
5. **No User Control:** User's `name` parameter affects only the HTML file content (intended for XSS challenge)

## 7. Vectors Analyzed and Confirmed Secure

| Attack Vector | Analysis Result | Details |
|--------------|-----------------|---------|
| Internal Service Access | **NOT POSSIBLE** | No URL parameters; PhantomJS accesses only localhost:5000 (itself) |
| Cloud Metadata Retrieval | **NOT POSSIBLE** | No outbound requests; no 169.254.169.254 access capability |
| Port Scanning | **NOT POSSIBLE** | No user-controlled ports; only port 5000 hardcoded |
| Protocol Smuggling | **NOT POSSIBLE** | No user-controlled protocols; only `http://` hardcoded |
| DNS Rebinding | **NOT POSSIBLE** | No DNS resolution of user input; only `localhost` used |
| Webhook Abuse | **NOT POSSIBLE** | No webhook functionality exists |
| File Scheme Abuse | **NOT POSSIBLE** | No `file://` support; only `http://` used |
| Redirect Following | **NOT POSSIBLE** | No redirect handlers; no Location header manipulation |

## 8. Unused Code (Dead Code Analysis)

The following imports/objects are present but NEVER USED:

```python
import urllib  # Line 9 - IMPORTED BUT NEVER CALLED
from flask import url_for  # Line 3 - IMPORTED BUT NEVER CALLED
from flask import Response  # Line 3 - IMPORTED BUT NEVER CALLED
from phantomjs import Phantom  # Line 13 - IMPORTED BUT NEVER CALLED
phantom = Phantom()  # Line 27 - INSTANTIATED BUT NEVER USED
```

**Security Implication:** While these imports exist, they pose **NO SECURITY RISK** because they are never invoked. The application could safely remove these imports without affecting functionality.

## 9. Conclusion

### SSRF Vulnerability Status: **NONE FOUND**

**Final Verdict:** This application is **SECURE** against Server-Side Request Forgery attacks.

**Summary:**
- ✅ NO user-controlled URL parameters
- ✅ NO outbound HTTP requests based on user input
- ✅ NO exploitable redirect handlers
- ✅ NO webhook or callback functionality
- ✅ NO API proxy endpoints
- ✅ PhantomJS integration uses server-controlled URLs exclusively

**Confidence Level:** **HIGH**

The application's architecture fundamentally prevents SSRF attacks by:
1. Not accepting URL/callback/webhook parameters
2. Not making outbound HTTP requests to user-specified destinations
3. Using hardcoded, server-controlled URLs for all internal operations
4. Employing cryptographic randomness for temporary file naming

**Exploitation Queue Status:** Empty - No vulnerabilities to pass to exploitation phase

**Recommendation:** No SSRF remediation required. Application follows secure design principles for request handling.

---

## 10. Files Analyzed

**Source Code:**
1. `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-013-24/src/app.py` (85 lines)
2. `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-013-24/src/constants.py` (204 lines)
3. `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-013-24/src/check.js` (49 lines)
4. `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-013-24/src/requirements.txt`
5. `/Users/arjunmalleswaran/Code/pentest-workspaces/XBEN-013-24/src/Dockerfile`

**Reconnaissance Reports:**
1. `deliverables/recon_deliverable.md`
2. `deliverables/pre_recon_deliverable.md`

**Analysis Date:** 2025
**Total Endpoints Analyzed:** 2
**Total SSRF Sinks Found:** 0
**Total Vulnerabilities Identified:** 0
