TIL. abbreviation for today I learned
used in writing, for example on social media, before giving interesting new information
It may not happen all the time, but every now and then there are cases where a certain outcome is expected due to two or more variables. For example the help or validation text for variable min and max values. Until now I have solved this with these monstrous “if – else if” nestings:Read More »TIL: Tuples and Pattern Matching in C# switch Statements
Challenge – Santa’s Secure Data Storage
In order to prevent the leakage of any flags, Santa decided to instruct his elves to implement a secure data storage, which encrypts all entered data before storing it to disk.
According to the paradigm Always implement your own crypto the elves designed a custom hash function for storing user passwords as well as a custom stream cipher, which is used to encrypt the stored data.…
Challenge – Those who make backups are cowards!
Santa tried to get an important file back from his old mobile phone backup. Thankfully he left a post-it note on his phone with the PIN. Sadly Rudolph thought the Apple was real and started eating it (there we go again…).…
Challenge – Threatened Cat
You can feed this cat with many different things, but only a certain kind of file can endanger the cat.
Do you find that kind of files? And if yes, can you use it to disclose the flag?…
Challenge – Twelve steps of Christmas
On the twelfth day of Christmas my true love sent to me…
twelve rabbits a-rebeling,
eleven ships a-sailing,
ten (twentyfourpointone) pieces a-puzzling,
and the rest is history.
You should definitely give Bread’s famous easy perfect fresh rosemary yeast black pepper bread a try this Christmas!…
Challenge – Docker Linter Service
Docker Linter is a useful web application ensuring that your Docker-related files follow best practices. Unfortunately, there’s a security issue in there…
This challenge requires a reverse shell. You can use the provided Web Shell or the VPN to solve this challenge (see
RESOURCES on top).…
Challenge – Santa’s lost home
Santa has forgotten his password and can no longer access his data. While trying to read the hard disk from another computer he also destroyed an important file. To avoid further damage he made a backup of his home partition.…
Challenge – Santa’s Gift Factory Control
Santa has a customized remote control panel for his gift factory at the north pole. Only clients with the following fingerprint seem to be able to connect:
Mission: Connect to Santa’s super-secret control panel and circumvent its access controls.…