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.
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 Parade_Buster-Final.7z
The first file contained the start of the PNG, while the last file ( part2_375.7z ) contained the . The offset for the hidden PNG data could
: 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 Challenge Overview The first file contained the start
The challenge provided a set of 376 individual 7zip archives (e.g., part2_0.7z through part2_375.7z ). Inside these archives were multiple "junk" files (e.g., junk_0.bin ), which initially appeared to be the primary data for extraction. Analysis & Solution
: Standard extraction and concatenation of the junk files failed to yield a valid binary.