PatriotCTF 2024 Dogdays Writeup

This page contains my writeup for the PatriotCTF 2024 Dogdays challenge. Challenge notes dogdays 426 Medium Woof woof http://chal.competitivecyber.club:7777 Author: Dylan (elbee3779) Files Download the dist.tar.xz challenge archive: wget --content-disposition --directory-prefix=dogdays \ "https://pctf.competitivecyber.club/files/293b2c364cb6ddfac14a9cf1cc9ed8b9/dist.tar.xz?token=…" Unpack the challenge archive to dogdays: tar xvf dogdays/dist.tar.xz -C dogdays The challenge archive contains these files: assets/ assets/BAD.gif assets/style.css assets/script.js index.php pupper/ pupper/3.png pupper/1.png pupper/2.png pupper/4.png pupper/5.png pupper/6.png pupper/7.png pupper/8.png view.php Here's what the challenge server shows you for index.php: Screenshot of the landing page at index.php Open in new tab (full image size 95 KiB) Take a look at view.php: <!-- view.php --> <?php $pic = $_GET['pic']; $hash = $_GET['hash']; if(sha1("TEST SECRET1".$pic)==$hash){ $imgdata =…