C32zip -

: Once lengths and CRC values are consistent, standard tools like 7z or unzip will be able to process the file correctly. CTFtime.org / PlaidCTF 2017 / zipper / Writeup

: The filename length field in the local file header is set to an impossibly large value (e.g., 9001 or 0x2329 ), causing extraction tools to fail or truncate the filename. C32zip

: Use binwalk or file to confirm it is a ZIP. Try to unzip it; if it fails with "filename too long" or "offset error," the headers are tampered with. : Once lengths and CRC values are consistent,

: Located at offset 0x0E . This is the checksum of the uncompressed data. Compressed Size (4 bytes) : Offset 0x12 . Uncompressed Size (4 bytes) : Offset 0x16 . Try to unzip it; if it fails with

: Open the file in a tool like 010 Editor or Hxd . Look for the filename length at 0x1A . If the actual filename is just a few characters (like flag.txt ) but the length is 9001 , manually change it to the correct length (e.g., 0x08 ).

To solve these "C32" related zip challenges, one must understand the ZIP file format : : Starts with the signature 50 4B 03 04 .