Posts

Steganography challenge - The Book of Secrets

10 minute read Published:

A small steganography challenge illustrating basic tricks used to hide data inside images. This post introduces the challenge, walks you through the soliution, and ends by describing how the challenge was created. The solution involves some basic JPG image screening, hexedit surgery, and password cracking with custom wordlists.
Steganography is the practice of hiding information inside other media like images, audio or video files, text, or pretty much anything else. It is different from encryption in that it aims not at making information unreadable but at concealing the very fact that it is there. Steganography and steganalysis (detection of steganography) are long-standing fields of research. Overviews of the field can be found, e.g., in Subhedar/Mankar (2014) or ZieliƄska/Mazurczyk/Szczypiorski (2014).

Hack The Box Write-up - SolidState

12 minute read Published:

Write-up for the machine SolidState from Hack The Box. Requires thorough port scanning to find an esoteric telnet admin interface of the Apache James email server. With default root credentials, you become James admin and break into people's email inboxes. Inside, you find SSH credentials, bypass a restricted shell and finally find an insecure cron job to escalate to root.
This is my second write-up for a machine from Hack The Box. It is again a rather easy one but still lots of fun. Lots of opportunities to do some oldschool telnet work on email servers. It starts with port scanning and illustrates the importance of scanning also more unpopular ports. After finding the email server with default credentials, you must use your administrator power to get code execution. Once on the box, all you have to do is finding an insecure cron job and you are root.

Hack The Box Write-up - Calamity

10 minute read Published:

Write-up for the Hack The Box machine called Calamity. Involves basic enumeration, finding a way into a hidden admin panel of the webserver, injecting PHP code after getting past the login, evading an intrusion detection system, recovering an SSH password hidden inside audio files and finally using LXD/LXD to exploit a user administration mistake to get root.
Hack The Box is a new company offering lab servers you can test penetration testing techniques on. It is quite educative and a lot of fun. They have multiple machines and all follow a similar pattern. You start with an IP address, have to find a way to get code execution on the machine (usually as an unprivileged user) and have to escalate from there to root. This post is about one of the machines called calamity.