HideToSee | picoCTF 2023 Solutions

Description

Steghide without a passphrase extracts a ciphertext which must then be decoded with an Atbash cipher.

Setup

Use steghide to extract embedded data from the JPEG (no password needed).

Open the resulting encrypted.txt and run it through an Atbash substitution cipher.

wget https://artifacts.picoctf.net/c/237/atbash.jpg

steghide extract -sf atbash.jpg

cat encrypted.txt

Step 1Extract the payload
Run steghide extract -sf atbash.jpg. When prompted for a passphrase, leave it blank and the tool writes encrypted.txt.
Step 2Decode with Atbash
Drop the ciphertext into CyberChef, apply the Atbash recipe, and copy the resulting picoCTF flag.

picoCTF{atbash_crack_05...}

The challenge name is the hint; Atbash is the only transformation required.