PicoCTF Writeup – What Lies Within
# Information:
CTF Name: PicoCTF
CTF Challenge: What Lies Within
Challenge Category: Forensics
Challenge Points: 150
PicoCTF 2019.
# Challenge Description:
There’s something in the building. Can you retrieve the flag?
Click on the word building to download the original image.
# Writeup
Once we read the description of the challenge we know that the flag should be found in the word building. This word has a link to an image. After downloading the image I opened it:
By looking at the image nothing seems relevant to help us get the flag.
Considering that the challenge category is Forensics I thought that maybe the information was inside the image, hidden in some way and that by doing a forensic analysis of the image I could retrieve the message (flag). After searching a little bit online, I was able to find out that there is a technique known as Steganography in which a message is hidden inside an image or video without compromising the quality.
It does not hurt to try this idea out! So I searched a little bit more for a tool that would decode messages from images. Meaning that this tool reveals the messages hidden using Steganography either in images or videos.
I was able to find this tool:
Special thanks to stylesuxx for this amazing tool.
After finding this tool I inserted the image and press decode, this was the result:
And the flag is
Show flag
picoCTF{h1d1ng_1n_th3_b1t5}
The image source can be found here.
Thank you very much for reading!
Cheers,
MRegra
Author Profile
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Hello, you can contact me via my contact page at: https://mregraoncyber.com/contact/
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Thanks for reading, have a nice day.
Cheers,
MRegra
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