pwnthem0le

Home Blog About GitHub

pwnthem0le is a Turin-based, hacking students group born out of CyberChallenge 2018. Read more about us!

18 October 2018

PicoCTF 2018 - QuackMe-Up WriteUp

by XxcoralloxX

Here is a new reverse challenge.

AltText

It is really intuitive, just running the programme we see that it “encrypt” your password, and print it. We need to dequack: “11 80 20 E0 22 53 72 A1 01 41 55 20 A0 C0 25 E3 20 30 00 45 05 35 40 65 C1”

The encryption seems to be done char by char and since same chars are encrypted in the same way we just need to “map” the output value of every char. (Black box analysis)

So:

I obtain all the encrypted chars (forgot ‘_’)

AltText

And wrote a script that decrypt every char:

AltText

And that’s it, really simple: picoCTF{qu4ckm3_cba51**7}

tags: reverse  PicoCTF2018