stegomedium

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hackerlab

Task: a cropped PNG screenshot contains hidden data after the IEND chunk due to Windows Snipping Tool not truncating the file (aCropalypse / CVE-2023-28303). Solution: extract trailing IDAT chunks, recover the deflate stream at the correct bit offset, and reconstruct the original full-screen image to reveal a bank card with the flag.

$ ls tags/ techniques/
pngimage_recoveryacropalypsecve_2023_28303windows_snipping_tooliend_trailer
acropalypse_exploitationpng_chunk_analysisdeflate_stream_recoverytrailing_data_extraction
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