Hacktivitycon 2021

Bad Words

Solved By : bobbysox

This challenge was interesting. 99% of characters that I entered were flagged as “Bad Words” After some trial and error, i got the first message down below “bash: fg: no job control”

I tried to implement some job control with no luck. However, when trying this, I noticed it processed “#! /bin/bash” without throwing errors. It processes the “/” character!!!! This made me take a step back and think about what were in. We’re in a custom restricted shell. In the past ive usually used native binaries to escape such situations. We have two options here: prefix our commands with “/”, or, try and call native binaries since we know we can just call any path. The latter seemed like the best solution. Call /bin/bash and see what happens. It worked!!! yay!

Published on : 20 Sep 2021