Ulli Weichert/ Mai 7, 2022/ IT-Security, Write-Ups/ 0Kommentare

McFly

125 points
Solves: 14 Easy
Riib_fc_I1deo_B1ff3n_Bpz_Yoo_Mdsxfkt_XoPxhatt

Flag format: EZ-CTF{D3c0d3d_Message}

Solving

This is a fun one 🙂

The hint for the challenge is this given picture

Okay what do we see here? This is Biff, the oponent of Marty McFly from the back to the future movies... a classic 😀
But something seems off in this picture... in the movie Biff does not have an ID card attached 🙂

I think the cipher that was used to encrypt the message was the biffid (bifid) cipher.

If we paste the encrypted message Riib_fc_I1deo_B1ff3n_Bpz_Yoo_Mdsxfkt_XoPxhatt in CyberChef and use the bifid cipher decode function.
The decoded message is: This_is_B1fid_C1ph3r_Are_You_Chicken_McFlyyyy

EZ-CTF{This_is_B1fid_C1ph3r_Are_You_Chicken_McFlyyyy}