Bypassing Rate Limits Like a Pro: Advanced Exploitation Techniques

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Basic info

Rate limiting is a fundamental security mechanism designed to prevent brute-force attacks, credential stuffing, and API abuse. However, many implementations contain weaknesses that attackers can exploit to bypass restrictions. This article explores advanced techniques used to evade rate limits, how tools like Burp Suite and ffuf automate attacks, and how security professionals can detect and mitigate these vulnerabilities.

Photo by Michael Dziedzic on Unsplash

Understanding Weak Rate-Limiting Mechanisms

Rate limits are typically enforced using one or more of the following strategies:

• IP-based limiting: Restricts requests from the same IP address.
• Session-based limiting: Limits actions within a specific user session.
• Header-based limiting: Uses custom headers to enforce restrictions.
• Time-based limiting: Allows a fixed number of requests per second/minute/hour.

Attackers bypass weak implementations by manipulating these constraints. Let’s explore some advanced techniques.

Rate Limit Bypass Techniques

1. Exploring Similar Endpoints

Attackers look for variations of the targeted endpoint to see if rate limits apply inconsistently. Examples:

/api/v3/sign-up
/Sing-up
/SignUp
/singup
/api/v1/sign-up
/api/sign-up

By rotating between multiple endpoints, an attacker can bypass rate limits applied to a single endpoint.

2. Incorporating Blank Characters in Code or Parameters

Adding blank bytes such as %00, %0d%0a, %20 can fool poorly implemented rate limit checks. Example:

code=1234%0a

This tactic is useful for circumventing login attempt restrictions by injecting variations of credentials.

3. Manipulating IP Origin via Headers

Many rate-limiting systems rely on IP addresses to track request counts…