403Fuzzer - Fuzz 403/401Ing Endpoints For Bypasses

403Fuzzer – Fuzz 403/401Ing Endpoints For Bypasses

Fuzz 403ing endpoints for bypasses

Follow on twitter! @intrudir

This tool will check the endpoint with a couple of headers such as X-Forwarded-For

It will also apply different payloads typically used in dir traversals, path normalization etc. to each endpoint on the path.
e.g. /%2e/test/test2 /test/%2e/test2 /test;/test2/


usage: 403fuzzer.py [-h] [-u URL] [-m {GET,POST,PUT,PATCH}] [-d DATA_PARAMS] [-c COOKIES] [-H HEADER] [-p PROXY] [-hc HC] [-hl HL] [-sf] [--save SAVE] [-sh] [-su]

use this script to fuzz endpoints that return a 401/403

optional arguments:
-h, --help show this help message and exit
-u URL, --url URL Specify the target URL
Specify the HTTP method/verb
Specify data to send with the request.
-c COOKIES, --cookies COOKIES
Specify cookies to use in requests. (e.g., --cookies "cookie1=blah; cookie2=blah")
-H HEADER, --header HEADER
Add headers to your request (e.g., --header "Accept: application/json" --header "Host: example.com"
-p PROXY, --proxy PROXY
Specify a proxy to use fo r requests (e.g.,
-hc HC Hide response code from output, single or comma separated
-hl HL Hide response length from output, single or comma separated
-sf, --smart Enable the smart filter
--save SAVE Saves stuff to a file when you get your specified response code
-sh, --skip-headers Skip testing bypass headers
-su, --skip-urls Skip testing path payloads

Basic examples

python3 403fuzzer.py -u http://example.com/test1/test2/test3/forbidden.html

Specify cookies to use in requests:

(minus the cookie header name) Examples:

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

Specify a method/verb and body data to send

403fuzzer.py -u https://example.com -m POST -d "param1=blah&param2=blah2"
403fuzzer.py -u https://example.com -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:

403fuzzer.py -u https://example.com -H "Some-Header: blah" -H "Authorization: Bearer 1234567"

Specify a proxy to use

Useful if you wanna proxy through Burp

403fuzzer.py -u https://example.com --proxy

Skip sending header payloads or url payloads

# skip sending headers payloads
403fuzzer.py -u https://example.com -sh
403fuzzer.py -u https://example.com --skip-headers

# Skip sending path normailization payloads
403fuzzer.py -u https://example.com -su
403fuzzer.py -u https://example.com --skip-urls

Hide response code/length

Provide comma delimited lists without spaces. Examples:

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

# Hide response lengths of 638
403fuzzer.py -u https://example.com -hl 638

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
403fuzzer.py -u https://example.com --smart

Save requests for matching response code

Will save to a file named saved.txt Useful for later inspection

 # save requests where the response code matched 200
403fuzzer.py -u https://example.com --save 200


  • Add other methods/verbs for bypass, e.g. POST requests
  • Maybe add an output file option for 200 OKs
  • Looking for ideas. Ping me on twitter! @intrudir

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