Why is my brute-force attack on a web application failing after a few attempts

Question

I’m running a brute-force attack on a web application’s login page for ethical hacking practice, but after a few attempts, the attack seems to be blocked. I’ve checked my script and the credentials list, and everything seems to be set up correctly, but the server stops responding to further login attempts after a while.

What could be causing my brute-force attack to fail after a few tries? Is this related to security mechanisms like rate-limiting or account lockouts? What are some ways I can test these mechanisms, and are there any ethical ways to bypass them for testing purposes?

Answer 1

If your brute-force attack is failing after a few attempts, here are some of the likely reasons behind it:

1. Rate Limiting: The application might be restricting the number of login attempts in a specific time frame. For example, if you fail logging in 5 times, the server blocks you for 10 minutes.

2. Account Lockout: Many web applications lock your accounts after a set number or failed login attempts. For example, your account can be locked for 30 minutes when you fail to login 3 times.

3. IP Blocking: If you try sending repetitive request from the same IP, the web application can trigger an automatic block to protect itself. For example, sending 20 requests from the same IP can result in server block for a period of time.

4. CAPTCHA Challenges: Several failed attempts might require you to verify the CAPTCHA to move ahead. For example, after 3 failed attempts, the web application might ask you to solve a CAPTCHA before trying again.

To test rate limiting and account lockout mechanisms, we can consider the following approaches:

1. Simulated Brute Force Attacks: We can use tools like Burp Suite or OWASP ZAP to automate login attempts while monitoring how the application responds.

2. Time-Based Testing: We can gradually increase the frequency of login attempts to find if the application is implementing rate limiting.

3. Examining Responses: We can analyze the HTTP responses to identify any messages indication rate limiting or account lockout. For example, "Too many attempts" or "Account locked".