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 : Parade_Buster-Final.7z
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 first file contained the start of the
Concatenating these extracted bytes from all files produced a final, valid image file named , which contained the flag for the challenge. CTFtime.org / TastelessCTF 2020 / 7/12 / Writeup valid image file named
