ProfessionalCommunity Edition

Credential stuffing with Burp Suite

• Last updated: June 18, 2024

• Read time: 3 Minutes

Credential stuffing is a form of brute-force attack in which you attempt to log into a website using known username and password combinations from other websites. These sets of credentials are usually collated from earlier data breaches.

These attacks rely on the fact that users often reuse the same credentials across multiple different sites. Crucially, as you're only attempting to access each account once, defense mechanisms such as account locking are effectively powerless against this kind of attack, although you may still need to bypass any rate limiting that's in place. For some ideas on how to do this, see the Authentication topic on our Web Security Academy.

Before you start

Obtain a list of known username and password pairs. For the example below, you can use the following wordlists. They are already sorted into correct pairs:

Steps

You can follow along with the process below using the Excessive trust in client-side controls lab from our Web Security Academy.

1. Send the request for submitting the login form to Burp Intruder.
2. Go to the Intruder > Positions tab and select the Pitchfork attack type.

3. In the request, highlight the username value and click Add § to mark it as a payload position. Do the same for the password.

   
4. Go to the Payloads tab and select Payload set 1.

5. Under Payload settings [Simple list], paste the list of usernames.

   
6. Select Payload set 2, and paste the list of passwords.
7. Click Start attack. The attack starts running in the new dialog. Intruder sends a request for each pair of usernames and passwords in the list.

8. When the attack is finished, study the responses to look for any behavior that may indicate a valid login. For example, look for any anomalous error messages, response times, or status codes. In the example below, one of the requests has received a 302 response.

   
9. To investigate the contents of a response in detail, right-click and select Send to Comparer (response). Do the same for the original response.
10. Go to the Comparer tab. Select the two responses and click Words or Bytes to compare the responses. Any differences are highlighted.