Fc2-ppv-1864525 May 2026

# 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:

sox audio.wav slice.wav trim 8 2 Open slice.wav in Audacity → “Plot Spectrum” → note the regular on/off bursts. fc2-ppv-1864525

zsteg -a frames/frame_00123.png No obvious LSB payload. The audio track is often used for hidden data. 6.1 Convert audio to WAV ffmpeg -i audio.aac audio.wav 6.2 Spectrogram inspection sonogram -i audio.wav -o spectrogram.png # (or use Audacity → Analyze → Plot Spectrum) The spectrogram shows a faint pattern resembling Morse code near 10 s. 6.3 Extract Morse Export the 8–10 s slice: # Get the offset of the final `moov` atom (e

Use exiftool on a few frames to see if any hidden data was appended: The audio track is often used for hidden data

But let’s assume the real challenge hides it deeper (e.g., the trailing data is just a decoy). We’ll keep digging to illustrate a full methodology. Even though we already located a flag, extracting the raw streams is useful for later analysis.

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

Using an online Morse decoder (or the morse Python library):