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Blue Sky Telemetry
Blue Sky Telemetry
Author: Prateet Gogia
This is a Steganography and Reverse Engineering-based CTF challenge demonstrating layered hidden data, red herrings, and custom firmware encryption.
Firstly for the Decoy part:
Running strings artifact.jpg yields a fake Base64 string decoding to CTF{y0u_g0dd4mn_r1ght_I_h1d_1t_but_n0t_h3r3}.
For the Steganography part:
First, we check the metadata. exiftool artifact.jpg reveals Artist : c3VwZXJzZWNyZXRrZXk=, which Base64 decodes to supersecretkey.
Next, we use this for the Archive Extraction. Running steghide extract -sf artifact.jpg -p supersecretkey drops payload.zip.
For the Reverse Engineering part:
Unzipping reveals intercept_log.txt (containing a Base32 decoy and a raw hex array) and firmware_snippet.c.
The C script shows the data was encrypted using (data[i] ^ 0x33) + 0x05.
To get the final flag, the player must write a script to reverse this operation chr((byte - 0x05) ^ 0x33) against the hex array to yield the final flag: CTF{h3is3nb3rg_c00k_t3l3m3try_99_1}.
Flag
CTF{h3is3nb3rg_c00k_t3l3m3try_99_1}