vee1e/Write-ups
1
0
Fork 0
mirror of https://github.com/vee1e/Write-ups.git synced 2026-09-01 11:08:39 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

Create Covert-Communications.md

Browse source
This commit is contained in:
Daksh Dadhania 2024-02-20 22:52:55 +05:30 • committed by GitHub
parent 7c416aa01c
commit 8c511ff345
No known key found for this signature in database
GPG key ID: B5690EEEBB952194
1 changed files with 21 additions and 0 deletions
Download patch file Download diff file Expand all files Collapse all files

21
BITSCTF-2024/Forensics/Covert-Communications.md Normal file
View file

@ -0,0 +1,21 @@
## Covert Communications Challenge Solution Overview
### Initial Analysis
Participants received a `.png` image and a `.wav` audio file. Initial examination of the `.wav` file's spectrogram revealed no secrets, but it was suggested to treat the audio as SSTV (Slow Scan Television) noise, leading to the discovery of another image.
### Decoding the SSTV Image
Using an SSTV decoding tool, the participants converted the audio file into an image that contained a ZIP archive named `secret.zip`, which was password-protected.
### Extracting the ZIP Archive
The password `mogambro` (found within the challenge context or possibly within the provided images) was used to unlock the ZIP archive, revealing two `.pkl` files: `enc_data.pkl` and `tempo.pkl`.
### Deciphering the Message
The challenge hinted at using Huffman coding and histogram analysis to decode the hidden message. The participants deduced that the `.png` image contained the encrypted message using steganography, specifically histogram shifting and Huffman coding.
### Using External Resources
A GitHub repository ([TejveerSingh13/Image-Steganography](https://github.com/TejveerSingh13/Image-Steganography)) was found that matched the challenge's requirements. This repository demonstrated how to use Huffman coding and histogram shifting for steganography.
### Decoding the Final Message
By applying the techniques from the GitHub repository to the provided image, the hidden message encoded in the image was successfully extracted.
The final flag was: `bitsctf{s73g4n06r4phy_15_n07_45_345y_45_17_533m5}`.