When Hackers Don't Take "Too Many Requests" for Answer!

Rate Limit Bypass - When Hackers Don't Take "Too Many Requests" for An Answer!

What is Rate Limiting?​

Rate Limiting is a security feature that limits the number of requests a user can make in a specific time frame.
Example: You can only attempt 5 OTP tries per minute.
But what if a hacker could bypass this limit and try 1000 OTPs in a minute?
That’s Rate Limit Bypass.

Real-Life Example: OTP Bruteforce​

Suppose a website sends a 6-digit OTP to log in. You are allowed only 5 attempts.
If rate limiting is weak, an attacker can:
Bruteforce 000000 to 999999
Bypass the limit and verify accounts without authorization

Common Techniques to Bypass Rate Limiting:​

1. IP Rotation (Using Proxies or TOR):
→ Change IP after each request
→ Tools: Burp Suite, [Turbo Intruder], [TorghostNG]
2. Header Manipulation:
→ Change or spoof headers like:
X-Forwarded-For: 127.0.0.1
X-Real-IP: 127.0.0.1
3. Changing HTTP Methods:
→ POST → GET, or GET → PUT to confuse backend filters
4. Multiple Sessions / Tokens:
→ Bypass by using different auth tokens or session cookies
5. Parameter Pollution:
→ Add junk parameters to trick WAF:

/verify?otp=123456 
/verify?otp=123456&bypass=true

6. Clustered Requests:
→ Send requests to multiple subdomains (api1.site.com, api2.site.com)

Tools for Rate Limit Testing:​

Burp Suite (Intruder + Repeater)
Turbo Intruder (for high-speed bruteforce)
ffuf – For testing endpoints and payloads
Tor + cURL / Python - IP rotation
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Tips for Bug Bounty Hunters:​

Target OTP / 2FA / Email verification endpoints
Look for endpoints that give status-based responses (200 OK, 401 Unauthorized)
Always try header spoofing + IP rotation
Test for consistent behavior after 5–10 failed attempts

Real-World Impact​

A successful rate limit bypass can lead to:
Account Takeover
Email/Phone verification bypass
DOS (Denial of Service)
Massive financial fraud

Defend It Like a Pro:​

Apply strict server-side rate limiting (not just at CDN)
Monitor behavior using anomaly detection
Use IP + user + device + session-based rules

"If you can send 1 request, you can send 1000 - unless rate limiting is done right."
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