Category: CTF

Ransomware attacks are becoming more common every day. This forensics challenge goes in depth into the solution of the 'Bad Ransomware' challenge of the CSCBE24 Qualifiers dealing with a Known Plain-Text Attack on an encrypted zip archive. We are given a ransomware encrypted file by "connemara" with a slight variation on the magic sequence.

For this years halloween I decided to participate in the Hack The Boo CTF competition from Hack the Box. Despite this being my first solo public CTF competition, I still managed to climb to leaderboards and reach top 50 (48th to be exact). In total I managed to capture 7 out of the 10 flags, some easier than others. In this post I will delve into how I managed to solve the forensics and web challenges, as those where the areas my skills stuck out the most.

Tasked with defending the antidote's research, a diverse group of students united against a relentless cyber onslaught. As codes clashed and defenses were tested, their collective effort stood as humanity's beacon, inching closer to safeguarding the research for the cure with every thwarted attack.

We are given the following files: Lets see what we are dealing with and list the protections that are enabled: Source code of main and save_msg functions. When we run the program and enter x, we get into the save_msg function that contains both a buffer overflow and format string vulnerability that we can exploit to execute system("/bin/sh") and read the flag on the file system.