Using Burp Suite’s Intruder

Objective

Learn how to use the Intruder tool in Burp Suite to perform automated attacks on web applications, such as fuzzing and brute-forcing, and understand how to secure applications against such attacks.

Purpose

Burp Suite’s Intruder tool allows testers to automate the process of testing web application inputs. It can be used to identify vulnerabilities like SQL injection, XSS, or weak authentication mechanisms. This lab demonstrates how to use Intruder effectively and highlights the importance of securing inputs against automated attacks.

Tools Required

• Burp Suite (Community Edition is sufficient).
• A web application to test (e.g., DVWA or OWASP Juice Shop).

Lab Topology

• Kali Linux: Running Burp Suite.
• Target Web Application: A test web application for exploitation.

Walkthrough

Task 1: Setting Up Burp Suite

1. Launch Burp Suite:
   • Open Burp Suite from the applications menu or terminal:

     burpsuite
     

2. Set Up the Proxy:
   • Configure your browser to use Burp’s proxy:
     • Proxy: 127.0.0.1
     • Port: 8080
3. Install Burp’s Certificate:
   • Navigate to http://burpsuite in your browser.
   • Download and install Burp’s CA certificate to intercept HTTPS traffic.
4. Access the Target Application:
   • Navigate to the target application in your browser while Burp Suite is running.

Task 2: Capturing a Request

1. Intercept a Login Request:
   • Log in to the target application with test credentials.
   • Intercept the request using the Proxy > Intercept tab in Burp Suite.
2. Send the Request to Intruder:
   • Right-click the intercepted request and select Send to Intruder.
3. Turn Off Interception:
   • In the Proxy > Intercept tab, click Intercept is off to stop further interception.

Task 3: Configuring the Intruder Attack

1. Set the Target:
   • Navigate to the Intruder > Target tab.
   • Confirm the target host and port.
2. Define Positions:
   • Go to the Positions tab.
   • Burp will highlight parts of the request that can be modified. Clear all markers with Clear§.
   • Highlight the parameter to attack (e.g., username) and click Add§.
3. Select an Attack Type:
   • Choose the attack type based on your objective:
     • Sniper: Single payload, one position at a time.
     • Battering ram: Same payload across all positions.
     • Pitchfork: Different payloads for each position.
     • Cluster bomb: All combinations of payloads.

Task 4: Adding Payloads

1. Navigate to the Payloads Tab:
   • Select the Payloads tab.
2. Set the Payload Type:
   • Choose Simple list for testing multiple usernames or passwords.
3. Add Payloads:
   • Example for brute-forcing usernames:

     admin
     user
     test
     guest
     

   • Paste the list into the Payload Options field.
4. Configure Additional Payload Settings (Optional):
   • Use prefix/suffix options or payload encoding as required.

Task 5: Launching the Attack

1. Start the Attack:
   • Click Start attack in the Intruder tab.
2. Monitor Results:
   • Observe the Status, Length, and Response columns to identify anomalies.
     • Example: A different Length or Status may indicate a successful login.
3. Analyze Findings:
   • Identify successful attempts or interesting responses for further investigation.

Task 6: Securing Against Intruder Attacks

1. Implement Input Validation:
   • Use server-side validation to sanitize inputs and prevent injection attacks.
2. Enforce Rate Limiting:
   • Implement rate limits or CAPTCHA mechanisms to block brute-force attacks.
3. Use Strong Authentication:
   • Enforce strong password policies and multi-factor authentication (MFA).
4. Monitor Logs:
   • Analyze server logs for unusual patterns, such as repeated failed login attempts.
5. Update Applications Regularly:
   • Patch known vulnerabilities and keep dependencies up to date.

Best Practices

1. Test on Authorized Applications Only:
   • Ensure you have explicit permission to test the application.
2. Document Findings:
   • Record vulnerabilities and remediation steps in detail.
3. Combine Tools:
   • Use Intruder alongside other tools like Repeater and Scanner for comprehensive assessments.
4. Educate Developers:
   • Train developers on secure coding practices to prevent vulnerabilities.

Key Takeaways

1. Burp Suite’s Intruder tool automates testing for vulnerabilities in web application inputs.
2. Identifying anomalies in responses can reveal weaknesses like injection points or weak authentication.
3. Implementing strong input validation and rate limiting can defend against automated attacks.

Troubleshooting Tips

1. No Anomalies Detected:
   • Verify the payloads and ensure they target the correct parameter.
   • Test different attack types or payloads.
2. Blocked by Application:
   • Use a lower attack speed or adjust headers to avoid detection by firewalls.
3. Intruder Limits (Community Edition):
   • Upgrade to Burp Suite Professional for faster attacks and additional features.

By completing this lab, you now understand how to use Burp Suite’s Intruder tool for automated testing and how to secure applications against such attacks.