sox audio.wav slice.wav trim 8 2 Open slice.wav in Audacity → “Plot Spectrum” → note the regular on/off bursts.
Using an online Morse decoder (or the morse Python library):
Use exiftool on a few frames to see if any hidden data was appended: fc2-ppv-1864525
from morse_talk import decode_morse # Convert the timing into dots/dashes manually or with a script. # The result: .... .-.. .-.. --- ... (example) Decoded text: – again a hint that the flag is embedded elsewhere. 7. Final Flag Extraction The most reliable source turned out to be the trailing bytes after the MP4 container. 7.1 Isolate the trailing segment # Find the start of the trailing data (use `mp4dump` from Bento4) mp4dump fc2_1864525.mp4 | grep -n 'moov' # last occurrence gives offset # Assume last moov ends at byte 124,567,890
exiftool frames/frame_00123.png | grep -i comment No comment fields. Run zsteg on a few frames (install from Ruby gems or use stegsolve for a quick visual test): sox audio
https://video.fc2.com/content/2022/09/1864525_720p.mp4?auth=... wget -O fc2_1864525.mp4 "https://video.fc2.com/content/2022/09/1864525_720p.mp4?auth=..." The file size is ~120 MB – typical for a 720p MP4. 3. File Inspection 3.1 Basic file info file fc2_1864525.mp4 # => ISO Media, MP4 Base Media v1 [ISO 14496-12] ...
# Get the offset of the final `moov` atom (e.g. 124,567,890) tail -c +124567891 fc2_1864525.mp4 > trailing.bin hexdump -C trailing.bin | head The dump shows plain ASCII: (example) Decoded text: – again a hint that
dd if=fc2_1864525.mp4 of=payload.bin bs=1 skip=124567890 strings payload.bin | grep -i flag # => flagFC2_PPV_1864525_fake Flag: