Advanced Web Application Security Testing Guide

Introduction

Web application security testing has evolved significantly in recent years, with new threats and attack vectors emerging constantly. This guide will walk you through advanced techniques for identifying and exploiting web application vulnerabilities, focusing on modern applications and their unique security challenges.

1. Modern Authentication Bypass Techniques

JWT Token Manipulation

JSON Web Tokens (JWT) are commonly used for session management, but they can be vulnerable to various attacks. Here's an example of a weak JWT implementation:

const jwt = require('jsonwebtoken');

// Vulnerable: Using a weak secret
const secret = '123456';
const token = jwt.sign({ user: 'admin' }, secret);

// Vulnerable: No algorithm specification
const decoded = jwt.decode(token);
                                

To test for JWT vulnerabilities:

• Check for algorithm confusion attacks
• Attempt null signature bypass
• Test for weak secrets using tools like jwt_tool

2. Advanced SQL Injection Techniques

While basic SQL injection is well understood, modern applications often require more sophisticated approaches:

Time-Based Blind Injection

-- Example of time-based blind SQL injection
SELECT * FROM users WHERE id = '1' AND IF(SUBSTRING(database(),1,1)='a',SLEEP(5),0)
                                

Detection techniques:

• Use benchmark() for MySQL
• pg_sleep() for PostgreSQL
• WAITFOR DELAY for MSSQL

3. GraphQL Security Testing

GraphQL APIs present unique security challenges. Here's a vulnerable query example:

query {
  user(id: "1") {
    id
    name
    email
    creditCard
    __schema {
      types {
        name
        fields {
          name
        }
      }
    }
  }
}
                                

Key testing areas:

• Introspection queries
• Batching attacks
• Depth and complexity limits

4. Modern XSS Prevention

Cross-Site Scripting attacks have evolved with modern frameworks. Here's a secure implementation example:

// React example with XSS prevention
import DOMPurify from 'dompurify';

function SafeHtml({ content }) {
  return (
    

  );
}
                                

5. SSRF in Cloud Environments

Server-Side Request Forgery in cloud environments can be particularly dangerous. Consider this vulnerable code:

import requests

def fetch_url(url):
    # Vulnerable: No validation of URL
    return requests.get(url)

# Could access internal metadata service
url = "http://169.254.169.254/latest/meta-data/"
response = fetch_url(url)
                                

Conclusion

Web application security testing requires constant learning and adaptation. The techniques covered here are just the beginning. Remember to:

• Stay updated with new vulnerabilities
• Practice in legal environments
• Document your findings properly
• Follow responsible disclosure policies