Parade_buster-final.7z

The PNG file was striped and hidden in the trailing bytes of the 7z archives, just before the footer.

The offset for the hidden PNG data could be calculated by comparing the reported "Packed Size" from the 7z -slt l command with the actual file structure. Parade_Buster-Final.7z

: Standard extraction and concatenation of the junk files failed to yield a valid binary. The PNG file was striped and hidden in

: To solve this, a script was used to loop through all 376 files, extract a specific block of bytes (typically 0x11 bytes) from each, and concatenate them. Final Result : To solve this, a script was used

The file Parade_Buster-Final.7z was the concluding challenge in the series from TastelessCTF 2020 . This write-up details the process of identifying a hidden PNG file embedded across hundreds of separate archives. Challenge Overview

The first file contained the start of the PNG, while the last file ( part2_375.7z ) contained the .

: Opening the first archive ( part2_0.7z ) in a hex editor revealed a PNG header ( 89 50 4E 47 ) and an IHDR chunk buried within the file structure itself, rather than in the extracted contents. The Pattern :