Category Archives: Linux Reversing

Da French? TL;DR Reverse executable that uses AES encryption and decrypt network traffic Description This was one of the harder challenges for the XMAS-CTF 2020 and I actually managed to be the third one that solved it. In the end, the challenge only had around 15 solves, which shows that many people did not see […]

Thou shall pass? TL;DR Reverse executable that uses clever function renaming techniques Description This was a challenge from the X-MAS CTF 2020. It was the easiest one in the Reversing category but I still think it was pretty fun because it introduced me to an interesting obfuscation technique. Challenge Description For thou to pass, the […]

s3-simple-secure-system TL;DR Extract RSA keys from executable and decrypt encrypted document Description This was a challenge at the ENISA Hackfest 2020, which posed as a replacement for the ECSC 2020 that was supposed to be held in Vienna but unfortunately got cancelled due to Covid19. This challenge was marked as easy. However, it took me […]

castorsCTF2020 TL;DR Investigating a Ransomware attack and trying to reverse the process Description This is the second part of a two part series. In this part, we’ll apply the knowledge we got from analysing the executable in part 1 and reverse the encrypted image Recap In part 1, we discovered that the executable contacts a […]

castorsCTF2020 TL;DR Investigating a Ransomware attack and try to reverse the process Description Ransomware has been an increasing problem for companies as well as normal internet users. Criminals use malware to encrypt files on your computer and they’ll only give you the decryption key if you transfer them a specified amount of money. castorsCTFs Ransom […]