uff's Introduction

uff - unleashed ffuf fork

Custom ffuf fork that relies on modified net/http and net/url libraries to avoid strict header and URL parsing.

Installation

To install uff, run the following command:

go install github.com/sw33tLie/uff@latest

Use cases

This effectively makes it possible to send various malformed or unsupported requests, such as:

Absolute URI FUZZING:

uff -c -u http://example.com -w vhosts.txt -opaque "http://FUZZ/"

GET http://anything-here/ HTTP/1.1
Host: example.com

Arbitrary HTTP method:

uff -c -u http://example.com/FUZZ -w wordlist.txt -X ASDASD

ASDASD /hi HTTP/1.1
Host: example.com

This is not possible in the normal ffuf because the net/http library only allows RFC-compliant HTTP methods.

Invalid url encoded character:

echo "%9f" | uff -c -u http://example.com/FUZZ -w -

GET /%9f HTTP/1.1
Host: example.com

Invalid header:

echo "%9f" | uff -c -u http://example.com/FUZZ -w - -H ' I AM AN INVALID: HEADER'

GET /%9f HTTP/1.1
Host: example.com
   I AM AN INVALID: HEADER

No header canonization

uff -c -u http://example.com/FUZZ -w wordlist.txt -H 'lowercase-header: weh'

GET /hi HTTP/1.1
Host: example.com
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/125.0.0.0 Safari/537.36
lowercase-header: weh
Accept-Encoding: gzip, deflate, br
Connection: keep-alive

Note how lowercase-header starts with a lowercase l.

Other customizations

Legit user agent instead of ffuf's default Fuzz Faster U Fool one.

Caveats

As of now, since the automatic content-length header calculation code was removed from net/http, you need to set your own Content-Length header if you're using the -d flag for POST data.