Cyber security

Bypass Fuzzer – Exploring A Powerful Tool For Testing End Point Security

This tool performs various checks via headers, path normalization, verbs, etc. to attempt to bypass ACL’s or URL validation.

It will output the response codes and length for each request, in a nicely organized, color coded way so things are reaable.

I implemented a “Smart Filter” that lets you mute responses that look the same after a certain number of times.

You can now feed it raw HTTP requests that you save to a file from Burp.

Usage

usage: bypassfuzzer.py -h

Specifying A Request To Test

Best Method: Feed It A Raw HTTP Request From Burp!

Simply paste the request into a file and run the script!

  • It will parse and use cookies & headers from the request.
  • Easiest way to authenticate for your requests
python3 bypassfuzzer.py -r request.txt

Using Other Flags

Specify A URL

python3 bypassfuzzer.py -u http://example.com/test1/test2/test3/forbidden.html

Specify Cookies To Use In Requests:
some examples:

--cookies "cookie1=blah"
-c "cookie1=blah; cookie2=blah"

Specify a method/verb and body data to send

bypassfuzzer.py -u https://example.com/forbidden -m POST -d "param1=blah&param2=blah2"
bypassfuzzer.py -u https://example.com/forbidden -m PUT -d "param1=blah&param2=blah2"

Specify custom headers to use with every request Maybe you need to add some kind of auth header like Authorization: bearer <token>

Specify -H "header: value" for each additional header you’d like to add:

bypassfuzzer.py -u https://example.com/forbidden -H "Some-Header: blah" -H "Authorization: Bearer 1234567"

Smart Filter Feature

Based on response code and length. If it sees a response 8 times or more it will automatically mute it.

Repeats are changeable in the code until I add an option to specify it in flag

NOTE: Can’t be used simultaneously with -hc or -hl (yet)

# toggle smart filter on
bypassfuzzer.py -u https://example.com/forbidden --smart

Specify A Proxy To Use

Useful if you wanna proxy through Burp

bypassfuzzer.py -u https://example.com/forbidden --proxy http://127.0.0.1:8080

Skip sending header payloads or url payloads

# skip sending headers payloads
bypassfuzzer.py -u https://example.com/forbidden -sh
bypassfuzzer.py -u https://example.com/forbidden --skip-headers

# Skip sending path normailization payloads
bypassfuzzer.py -u https://example.com/forbidden -su
bypassfuzzer.py -u https://example.com/forbidden --skip-urls

Hide Response Code/Length

Provide comma delimited lists without spaces. Examples:

# Hide response codes
bypassfuzzer.py -u https://example.com/forbidden -hc 403,404,400  

# Hide response lengths of 638
bypassfuzzer.py -u https://example.com/forbidden -hl 638  
Varshini

Varshini is a Cyber Security expert in Threat Analysis, Vulnerability Assessment, and Research. Passionate about staying ahead of emerging Threats and Technologies.

Recent Posts

Cybersecurity – Tools And Their Function

Cybersecurity tools play a critical role in safeguarding digital assets, systems, and networks from malicious…

2 hours ago

MODeflattener – Miasm’s OLLVM Deflattener

MODeflattener is a specialized tool designed to reverse OLLVM's control flow flattening obfuscation through static…

2 hours ago

My Awesome List : Tools And Their Functions

"My Awesome List" is a curated collection of tools, libraries, and resources spanning various domains…

2 hours ago

Chrome Browser Exploitation, Part 3 : Analyzing And Exploiting CVE-2018-17463

CVE-2018-17463, a type confusion vulnerability in Chrome’s V8 JavaScript engine, allowed attackers to execute arbitrary…

2 hours ago

Chrome Browser Exploitation, Part 1 : Introduction To V8 And JavaScript Internals

The blog post "Chrome Browser Exploitation, Part 1: Introduction to V8 and JavaScript Internals" provides…

2 hours ago

Chrome Browser Exploitation, Part 3: Analyzing and Exploiting CVE-2018-17463

The exploitation of CVE-2018-17463, a type confusion vulnerability in Chrome’s V8 JavaScript engine, relies on…

5 hours ago