picoCTF Riscy Writeup

Aidan — Sat, 15 Feb 2025 14:12:00 +0000

Riscy

Analysis and solution of picoCTF’s RE Hard question Riscy

First contact

First thing was to run file on the provided binary, which yields the following:

`1`	`riscy: ELF 64-bit LSB executable, UCB RISC-V, RVC, double-float ABI, version 1 (SYSV), statically linked, stripped`

As expected based on the title, RISC-V. Just a few points of interest, RVC means we can expect to see compressed instructions, which are the same but smaller. e.g. li can become c.li, using half the size for the instruction at the cost of supporting smaller values to load. It’s statically linked, so no external libraries needed, but also that means that’s not a method to attack it. Finally, it’s stripped, which isn’t the end of the world, an ELF will always give us entry.

Password cracking on Beoshock

Aidan — Thu, 06 Feb 2025 17:51:00 +0000

Password Cracking on Beoshock with Hashcat and John

Getting on Beoshock

Applying

https://wichita.teamdynamix.com/TDClient/1907/Portal/Requests/ServiceDet?ID=41427
List your intended use as something like “NCL Password Cracking” and your academic advisor as Sergio’s email (omitted for web).

Connecting

You’ll ssh into the head node at first, this is where most of the prep happens.
Use ssh a123b456@hpc-login.wichita.edu with your actual student ID. This should work anywhere on-campus, it’s whitelisted.
When it’s time to crack, use an srun or sbatch to use the actually powerful nodes (we’ll cover that in a following section).

CTF on The Owlgorithm