Rating: 0

### InCTF 2018

##### Category: Stegano

##### Points: 1000

##### Solves: 1/306

##### Description: A number station in Russia broadcasted a series of encoded messages to one of it's intelligence agency. We have been able to get a piece of that message along with a picture hidden by one of the spy. Decode the transmitted data and be a hero!!

In this challenge we had a PNG file of 40,8MB (“index.png”) and an audio file (“new.mp3”).

Opening the mp3 file with audacity we realize that it was a message transmitted in Morse.

After decode it, we got the following message:


FLAGISNOTH3R3


So we had to find the flag in other place...

After playing a bit with both files, we detected the numbers “1517” in the LSB colors of the image “index.png”:

Here we were stuck a long time, trying different things with no success, until that, thanks to the name of the challenge, we found a stego tool called “StegoMagic” (https://tech2copycat.wordpress.com/2012/02/06/how-to-hide-data-in-image-audio-video-files-steganography/#more-30).

After using “StegoMagic_BIN.exe” over the mp3 file with the password “1517” we extracted a PNG file with a QR code:

This QR Code gave us the URL “http://qrs.ly/ai7bsyn” whose content was:

Ob>(FfBIDELM1nJQ56TtP:XxTU\]^YZ"\cdefgK*dkfg/iSkr4nXp8rsz{|w~!zB|%&hG#*%&-op0P,-4/w189Y5}=]9@;<C'?eAHIJKFGmIPKLSTUPQXS=zV]X_ZaE$^Hgh*delmniS2lVn6pqxyt^|>x!"{|%g'(H$l,-M)*+2t4T078zY5<=8"@ABb>EFG+hDKLGH23pLMTUVQwSZ[\@^~Z[bcdegK*dklgnipT3mtupwxy]<v}~!"#eD~!"j*+K'./01stS/67834|[78?:A%b>EF*BIJjFM1nJ45STtPWXYT[VW^B"\]d_I(bcjkfP/ijkrm5ovwxyt{=w~yz#$fE!()*+m'M)*+,R./0723{5[7>?@AB='d@GBC-ELlHO34qM7UVWXxT[\]A~Z[\cdefJK*dklgnipT3mtuYqx])^OP>!d{$VE4F6l%nLo