Forest

Author: pwn4magic
Category: Stego
Points: 40

Challenge Description

Explore the forest and capture the flag!

Approach

First, I tried running strings but nothing interesting came up.
The next thing I did ws browse through forest.jpg with stegsolve. Several planes and maps (red 0, green 0, blue 0, and random colour maps) revealed some text that looked like "IsJuS1Af0r3sTbR0".
Since the image is a jpg, steghide might be able to extract information from it. I used "IsJuS1Af0r3sTbR0" as the password.

$ steghide info forest.jpg
"forest.jpg":
  format: jpeg
  capacity: 134.9 KB
Try to get information about embedded data ? (y/n) y
Enter passphrase:
  embedded file "nothinghere.txt":
    size: 428.0 Byte
    encrypted: rijndael-128, cbc
    compressed: yes

$ steghide extract -sf forest.jpg
Enter passphrase:
wrote extracted data to "nothinghere.txt".

nothinghere.txt contains encrypted information. It was encrypted with ROT13:

The forest is a complex ecosystem consisting mainly of trees that buffer the earth and support a myriad of life forms. The trees help create a special environment which, in turn, affects the kinds of animals and plants that can exist in the forest. Trees are an important component of the environment. They clean the air, cool it on hot days, conserve heat at night, and act as excellent sound absorbers. HTB{AmAz1nGsKilLzZBr0}

Flag

HTB{AmAz1nGsKilLzZBr0}