From 8c511ff345a82ba752b24e25e0878c24b16976b2 Mon Sep 17 00:00:00 2001 From: Daksh Dadhania <63968989+DakshDadhania@users.noreply.github.com> Date: Tue, 20 Feb 2024 22:52:55 +0530 Subject: [PATCH] Create Covert-Communications.md --- .../Forensics/Covert-Communications.md | 21 +++++++++++++++++++ 1 file changed, 21 insertions(+) create mode 100644 BITSCTF-2024/Forensics/Covert-Communications.md diff --git a/BITSCTF-2024/Forensics/Covert-Communications.md b/BITSCTF-2024/Forensics/Covert-Communications.md new file mode 100644 index 0000000..1e8f326 --- /dev/null +++ b/BITSCTF-2024/Forensics/Covert-Communications.md @@ -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}`.