0x90skids Capture the Flag.

0x90skids CTF is a collection of challenges created by team members. Click the challenge card to expand for details.


Author: tbutler0x90
Help Save Dustin

It’s the early 90’s and several years after the last season Stranger Things. Mike and the gang are home in Hawkins after their first semester of college. Eleven, Hopper, and Dustin recently came across some weird activity in the Hawkins Community library, and mentioned something about it being a front for Russian Intelligence operations. They’ve all gone missing and the only clue is this cryptic message Dustin sent in an IM chat. Can you help Mike and the gang find where they went?

Flag 1: Find the secret form

Flag 2: Find dustin’s message in the russian database

Flag 3: Find the admin’s secret message


Author: cernec1999

Just a simple calculator application. Nothing suspicious to see here!

There’s two challenges here that each yield their own flag. Both challenges have the same source code, but one challenge has a different compiler option enabled. Can you guess which one?

The challenge repository is linked here. To solve remotely, connect to the TCP servers.

simplecalc0 is at nc server.cerne.xyz 1337 and simplecalc1 is at nc server.cerne.xyz 1338



Author: not-matthias

Ferris sent me this virtual machine with some opcodes. Whenever I try to run it it hangs, can you help me get the flag?

Linux and Window binaries can be downloaded from here.