PicoCTF_2017: SoRandom

Category: Cryptography Points: 75 Description:

We found sorandom.py running at shell2017.picoctf.com:16768. It seems to be outputting the flag but randomizing all the characters first. Is there anyway to get back the original flag?

Hint:

How random can computers be?

Write-up

Firstly, it doesn't seem to be a random random.

$ nc shell2017.picoctf.com 16768
Unguessably Randomized Flag: BNZQ:449xg472190mwx6869b8pt10rwo92624

Looking in the sorandom.py code, we see that the random generator has already been preseeded!

random.seed("random")

Okay, let's crack our Python knuckles and get to work.

$ ./crack.py
FLAG: 107bd559693aef6692e1ed55ebe29514

Therefore, the flag is 107bd559693aef6692e1ed55ebe29514.

results matching ""

    No results matching ""