The impossible challenge | TryHackMe

The impossible challenge is a cryptography based challenge which deals with Unicode zero-width characters steg “hiding a text message in spaces in a text”

level:Medium

The challenge provides some cipher text and a download file which is a zip file

First i download the “Task files” which was a zip file,i decided to unzip the file but to no luck the zip file had a protected password

but it has some hint where the flag for the challenge is located in the flag.txt file.After using john the ripper to crack the password it was just a waste of time.

Then i decide to decode the cipher text which was provided in the web page using “cyberchef” http://icyberchef.com/.

process to decode the cipher:

rot13 , rot47,hex,base64 or rot13 ,rot47, magic “magic is a method in cyberchef which simplify the decoding process.

in the output field ,result snippet the text says “It’s inside the text, in front of your eyes!”,i decided to inspect the web page element and to my luck i found that the “Hmm” text from the tittle has some red ‘0’

i search around and i found that they have used unicode zero-width to hind the text .i search from google about unicode zero-width and i found a tool to decode the text “copy the ‘Hmm’ from the tittle which contains 163 characters” and decode it using https://330k.github.io/misc_tools/unicode_steganography.html

The password is in the format “hxxxxxz”

N/B:After copying the “Hmm” into the decoder make sure to encode it the decode to get the hidden message

I used the found password to open the zip file and the flag is located in the flag.txt file