Write Up - Layer Tersembunyi

Write Up - Layer Tersembunyi

Deskripsi

Gambar terlihat biasa, tapi pesan disembunyikan di bit-plane (LSB).

File

wget 'https://raw.githubusercontent.com/ariafatah0711/fgte_s1/refs/heads/main/04_forensics/layer_tersembunyi/cat.png' -O cat.png

Langkah

1. Cek file:

file cat.png exiftool cat.png

2. Cek stego:

zsteg -a cat.png

3. Ekstrak LSB green channel:

zsteg -E 1b,g,lsb,xy cat.png > b1_g_lsb.raw

4. Ubah raw jadi gambar:

convert -size 640x800 -depth 1 gray:b1_g_lsb.raw lsb_g.png

5. Perjelas lalu OCR:

convert lsb_g.png -resize 400% -threshold 50% lsb_g_bw.png tesseract lsb_g_bw.png stdout -l eng --psm 7

Flag

FGTE{4_bit_Plane}

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