# SSRF Analysis Report

## 1. Executive Summary
- **Analysis Status:** Complete
- **Key Outcome:** Zero exploitable SSRF vulnerabilities identified. The application makes no outbound HTTP requests based on user-controlled input.
- **Purpose of this Document:** This report provides comprehensive analysis of the "Dalgona Challenges" XSS training platform's outbound request mechanisms and confirms the complete absence of Server-Side Request Forgery attack vectors. The application's architecture is stateless and intentionally minimal, focusing exclusively on client-side XSS challenges without any server-side request-making functionality.

## 2. Application Context

**Application Name:** Dalgona Challenges (XBEN-049-24)  
**Purpose:** Flask-based Cross-Site Scripting (XSS) training platform  
**Technology Stack:**
- Backend: Python 2.7.18 (EOL) with Flask 1.1.4
- Validation: PhantomJS 2.1.1 (abandoned project)
- Architecture: Stateless monolithic application with no database
- Network Surface: 2 functional endpoints (`/`, `/page`)

**Security Posture:** This is an intentionally vulnerable application designed for XSS training. The primary vulnerability is reflected XSS, not SSRF. The application has zero authentication, authorization, or access controls.

## 3. Dominant Vulnerability Patterns

### Pattern 1: No Outbound HTTP Request Mechanisms
- **Description:** The application does not implement any functionality that makes outbound HTTP requests based on user input.
- **Implication:** Without user-controlled outbound requests, SSRF vulnerabilities cannot exist.
- **Evidence:** Comprehensive analysis of all HTTP client libraries, subprocess calls, and request-making functions confirms zero SSRF attack surface.

### Pattern 2: Server-Controlled PhantomJS URLs
- **Description:** PhantomJS is used for XSS validation but receives only server-generated URLs pointing to localhost.
- **Implication:** While PhantomJS can navigate to URLs, the URLs are hardcoded to `http://localhost:5000/static/[random].html` with no user influence.
- **Evidence:** Analysis of `src/app.py:35-36` shows URL construction using `os.urandom(16).encode('hex')` for filename generation.

### Pattern 3: Unused HTTP Client Import
- **Description:** The `urllib` module is imported but never used anywhere in the application.
- **Implication:** This is dead code that poses no security risk but indicates poor code hygiene.
- **Evidence:** Grep search for `urllib.` across entire codebase returns zero results beyond the import statement.

## 4. Strategic Intelligence for Exploitation

### HTTP Client Architecture
**Finding:** This application does NOT use any HTTP client libraries for outbound requests.

**Libraries Analyzed:**
- `urllib` - Imported at `src/app.py:9` but NEVER used (dead import)
- `urllib2` - Not imported
- `urllib3` - Not imported  
- `requests` - Not imported
- `httplib`/`http.client` - Not imported

**PhantomJS Usage:**
- **File:** `src/app.py:34` and `src/check.js:20`
- **Purpose:** Client-side XSS validation via headless browser
- **URL Source:** Server-generated, not user-controlled
- **Code:**
```python
# src/app.py:35-36
fn = "static/" + os.urandom(16).encode('hex') + '.html'
url = 'http://localhost:5000/' + fn
proc.stdin.write(url)  # URL passed to PhantomJS
```

**Why This is NOT SSRF:**
1. Protocol hardcoded: `http://`
2. Hostname hardcoded: `localhost:5000`
3. Path prefix hardcoded: `static/`
4. Filename randomly generated: `os.urandom(16).encode('hex')`
5. No user input in URL construction

### Request Architecture
**Data Flow Analysis:**

```
User Input (?name=payload)
    ↓
Weak XSS Filtering (removes <script> and "XSS")
    ↓
HTML Template Injection (XSS vulnerability - intentional)
    ↓
File Write (static/<random>.html)
    ↓
Server-Generated URL Construction
    ↓
PhantomJS Navigation (localhost only)
```

**Critical Points:**
- User input affects HTML **content**, not URL **destination**
- All outbound requests are to `localhost:5000` (self-referential)
- No mechanism for external URL access exists

### Internal Services
**Finding:** No internal service discovery or access mechanisms exist.

The application:
- Does not make requests to cloud metadata endpoints
- Does not access internal network services
- Does not proxy requests to other systems
- Does not fetch data from external APIs
- Does not implement webhooks or callbacks

## 5. Secure by Design: Validated Components

These components were analyzed and found to have NO SSRF vulnerabilities. They represent the complete set of potential SSRF sinks in the application.

| Component/Flow | Endpoint/File Location | Defense Mechanism Implemented | Verdict |
|---|---|---|---|
| PhantomJS URL Construction | `src/app.py:35-36` | URL is entirely server-controlled with hardcoded protocol, hostname, and randomly generated filename using `os.urandom(16)`. No user input influences URL structure. | SAFE |
| File Operations | `src/app.py:22, 38, 50` | Python's built-in `open()` function does not support URL wrappers (unlike PHP). All file paths are either hardcoded (`secret.txt`) or randomly generated. No file:// or http:// scheme support. | SAFE |
| urllib Import | `src/app.py:9` | Module imported but never used. No calls to `urlopen()`, `urlretrieve()`, or any other HTTP-making functions exist in codebase. Dead import with zero security impact. | SAFE |
| Static File Serving | Flask built-in handler | Standard Flask static file serving. No user-controlled paths or URL parameters that could be exploited for SSRF. | SAFE |

## 6. Detailed Analysis by SSRF Category

### 6.1 URL Manipulation / Direct HTTP Requests
**Status:** NOT VULNERABLE

**Analysis:**
- No endpoints accept URL parameters for fetching
- No "fetch URL" or "load from URL" functionality
- No HTTP client library usage (requests, urllib, httplib)
- No API proxy or gateway functionality

**Methodology Applied:**
1. ✅ Identified HTTP Client Usage Patterns - NONE FOUND
2. ✅ Protocol and Scheme Validation - N/A (no user URLs accepted)
3. ✅ Hostname and IP Address Validation - N/A (no user URLs accepted)
4. ✅ Port Restriction and Service Access Controls - N/A (no user URLs accepted)

**Conclusion:** Zero URL manipulation vectors exist.

### 6.2 Redirect Abuse
**Status:** NOT VULNERABLE

**Analysis:**
- No Flask `redirect()` usage in codebase
- No HTTP 302/301 responses generated
- No "next" or "return_url" parameters
- No Location header manipulation
- No meta refresh or JavaScript redirects

**Evidence:**
```python
# Import analysis - src/app.py:1
from flask import Flask, request, Response, make_response, url_for
# Note: 'redirect' is NOT imported
```

**Methodology Applied:**
1. ✅ Searched for redirect functions - NONE FOUND
2. ✅ Checked for redirect parameters - NONE FOUND
3. ✅ Analyzed response headers - NO LOCATION HEADERS

**Conclusion:** Zero redirect-based SSRF vectors exist.

### 6.3 Webhook Injection / Callback URLs
**Status:** NOT VULNERABLE

**Analysis:**
- No webhook configuration endpoints
- No callback URL parameters
- No "ping my URL" functionality
- No event notification system
- No API endpoint validation tools

**Conclusion:** Zero webhook-based SSRF vectors exist.

### 6.4 Service Discovery / Internal Network Access
**Status:** NOT VULNERABLE

**Analysis:**
- PhantomJS only accesses `localhost:5000` (self-referential)
- No cloud metadata endpoint access
- No internal service enumeration
- No port scanning capabilities
- No DNS resolution of user-supplied hostnames

**Conclusion:** Zero internal service access vectors exist.

### 6.5 File Fetch Abuse / Remote Includes
**Status:** NOT VULNERABLE

**Analysis:**
- Python's `open()` does NOT support URL wrappers (file://, http://, ftp://)
- All file paths are hardcoded or randomly generated
- No "import from URL" functionality
- No remote configuration loading
- No file upload with URL fetching

**File Operations Inventory:**
1. `open('secret.txt')` at line 22 - Hardcoded filename
2. `open(fn, 'w')` at line 38 - Random filename (`os.urandom(16).encode('hex')`)
3. `os.unlink(fn)` at line 50 - Same random filename from #2

**Methodology Applied:**
1. ✅ Analyzed all `open()` calls - NO USER INPUT
2. ✅ Checked for URL wrapper support - NONE (Python limitation)
3. ✅ Searched for remote file includes - NONE FOUND

**Conclusion:** Zero file-based SSRF vectors exist.

### 6.6 API Proxy Bypass
**Status:** NOT VULNERABLE

**Analysis:**
- No API proxy functionality exists
- No request forwarding mechanisms
- No header injection opportunities
- No credential theft via proxied requests

**Conclusion:** Zero API proxy vectors exist.

## 7. Vectors Analyzed and Confirmed Secure

### Complete SSRF Sink Analysis

The pre-reconnaissance phase identified one potential SSRF sink: **PhantomJS page.open()**. Below is the comprehensive backward taint analysis confirming this sink is NOT exploitable.

#### Sink 1: PhantomJS page.open() - SECURE

**Location:** `src/check.js:20`

**Sink Code:**
```javascript
var input = system.stdin.readLine();
page.open(input, function(status) {
    // ... XSS validation logic ...
});
```

**Backward Taint Analysis:**

**Step 1: Trace stdin input source**
```python
# src/app.py:43
proc.stdin.write(url)
```
The `url` variable is written to PhantomJS stdin.

**Step 2: Trace url variable origin**
```python
# src/app.py:35-36
fn = "static/" + os.urandom(16).encode('hex') + '.html'
url = 'http://localhost:5000/' + fn
```

**Step 3: Analyze URL construction components**
- Protocol: `'http://'` - **HARDCODED** (no user input)
- Hostname: `'localhost:5000'` - **HARDCODED** (no user input)
- Path prefix: `'static/'` - **HARDCODED** (no user input)
- Filename: `os.urandom(16).encode('hex') + '.html'` - **CRYPTOGRAPHICALLY RANDOM** (no user input)

**Step 4: Trace filename generation**
```python
fn = "static/" + os.urandom(16).encode('hex') + '.html'
```
- Uses `os.urandom(16)` - Generates 16 random bytes (128-bit entropy)
- Encodes as hex - Produces 32-character hex string
- Appends `.html` extension
- **ZERO user input in filename generation**

**Step 5: Check for user input in data flow**
```python
# src/app.py:65
msg = request.args.get('name','')  # User input acquired here
# Lines 66-67: Weak filtering applied
# Line 68: Used in HTML template
value =  "" if msg == "" else 'value="{0}"'.format(msg)
# Line 70: Template formatting
data = XSS_CONTENT.format("15", "Triangle", value, "", "")
# Line 71: Passed to check_input()
result = check_input(data,flags[0],msg,'level_easy_med')
```

**Step 6: Track user input through check_input()**
```python
def check_input(page,flag,msg,tag):
    # 'page' parameter contains HTML with user input
    # Line 38-40: HTML written to file
    of = open(fn, 'w')
    of.write(page)  # User input is in FILE CONTENT
    of.close()
    # Line 43: URL (NOT content) sent to PhantomJS
    proc.stdin.write(url)
```

**Critical Observation:**
- User input flows into `page` parameter (HTML content)
- `page` is written to file at path `fn`
- `url` pointing to `fn` is sent to PhantomJS
- User input affects **file contents**, NOT **URL structure**

**Sanitization Check:**
- **Context:** Server-side URL construction for PhantomJS navigation
- **Required Defense:** No user input should influence URL protocol, hostname, port, or path
- **Actual Defense:** URL is 100% server-controlled with zero user input
- **Mutation Check:** No concatenations or transformations occur between URL generation and PhantomJS consumption
- **Verdict:** SECURE - Perfect isolation between user input (file content) and URL destination

**Confidence:** HIGH

**Conclusion:** This sink is **SECURE**. User input cannot influence the URL that PhantomJS navigates to. The intended vulnerability here is XSS (user input in HTML content), not SSRF (user input in URL destination).

---

## 8. False Positive Prevention

### Why Commented Code Was Excluded

**File:** `src/check.js:2-3`
```javascript
// var json = JSON.parse(system.args[1]);
// var input = json.url;
```

**Analysis:**
- These lines are commented out and do NOT execute
- If they were active, they WOULD create an SSRF vulnerability (URL from command-line args)
- However, the active code uses `system.stdin.readLine()` instead (line 4)
- Commented code is excluded per scope definition (must be "network-accessible and active")

**Decision:** NOT reported as vulnerability (inactive code).

### Why unused imports were excluded from findings

**Import:** `import urllib` at `src/app.py:9`

**Analysis:**
- Module imported but never used (zero function calls)
- Represents dead code / poor code hygiene
- Does not create an exploitable SSRF surface
- Should be removed but is not a vulnerability

**Decision:** Documented as "dead import" but NOT counted as SSRF vulnerability.

---

## 9. Network Boundary Analysis

### External Attacker Perspective (Scope Compliance)

**Target:** `http://localhost:42211`

**Question:** Can an external attacker exploit SSRF to:
1. Access internal services? **NO** - No SSRF vectors exist
2. Retrieve cloud metadata? **NO** - No SSRF vectors exist
3. Perform port scanning? **NO** - No SSRF vectors exist
4. Bypass network segmentation? **NO** - No SSRF vectors exist

**Scope Compliance:**
- All analysis focused on network-accessible endpoints
- Zero findings require internal network access
- All potential SSRF sinks were traced and found secure
- PhantomJS requests are self-referential (localhost only)

**Conclusion:** This application is NOT vulnerable to SSRF from an external attacker perspective.

---

## 10. Summary

### Analysis Completeness
✅ All HTTP client imports analyzed  
✅ All subprocess calls analyzed  
✅ All file operations analyzed  
✅ All redirect mechanisms analyzed  
✅ All PhantomJS/browser navigation calls analyzed  
✅ All potential user input vectors traced  
✅ All network-accessible endpoints reviewed  

### Key Findings
- **Total SSRF Vulnerabilities Found:** 0 (zero)
- **Total Potential Sinks Analyzed:** 4 (PhantomJS, urllib, file ops, redirects)
- **Total Secure Components:** 4 (all analyzed sinks are secure)
- **External Exploitability:** None

### Architectural Assessment
This application is designed as an XSS training platform, not a service that makes outbound HTTP requests. The architecture is fundamentally incompatible with SSRF vulnerabilities because:
1. No HTTP client libraries are used
2. No user-controlled URLs are accepted
3. The only outbound request mechanism (PhantomJS) uses server-controlled URLs
4. All URLs point to localhost (self-referential)

### Recommendation for Exploitation Phase
**DO NOT allocate resources to SSRF exploitation for this target.** Zero exploitable SSRF vulnerabilities exist. The reconnaissance and analysis phases have conclusively determined that this application does not make user-influenced outbound HTTP requests.

Focus exploitation efforts on the application's actual vulnerability: **Reflected Cross-Site Scripting (XSS)** via the `?name=` parameter on the `/page` endpoint.

---

## 11. Conclusion

After systematic analysis of all potential SSRF attack vectors following the prescribed methodology, I can conclusively state:

**ZERO EXPLOITABLE SSRF VULNERABILITIES EXIST IN THIS APPLICATION.**

The "Dalgona Challenges" application is a stateless XSS training platform with no outbound request mechanisms that accept user input. The PhantomJS component, while capable of making HTTP requests, receives only server-controlled URLs pointing to localhost. No URL manipulation, redirect abuse, webhook injection, file fetch, or API proxy vulnerabilities are present.

This assessment is based on comprehensive white-box code analysis with HIGH confidence. The application's minimalist architecture and lack of HTTP client usage make SSRF attacks impossible from a network-accessible attacker's perspective.

**Analysis Status:** COMPLETE  
**Exploitation Queue Status:** Empty (zero vulnerabilities to queue)  
**Recommended Next Phase:** Skip SSRF exploitation; focus on XSS exploitation