7z2john.pl: unsupported coders/filters
Author: AlbertVeliCreated Aug 11, 2026Updated Aug 11, 2026
Labelsenhancement
In the 2026 Crack Me If You Can contest challenge 2 contained 5 .7z files that have newer coders/filters that are not supported by 7z2john.pl.
The challenge can be downloaded from https://contest-2026.korelogic.com/downloads/ and decrypted with:
gpg --batch --passphrase '46d;;Ho@]3LgfH3t-z#)' -d cmiyc_2026_challenge_2.tar.pgp > cmiyc_2026_challenge_2.tarThis produces 5 .7z files. Running 7z2john.pl gives:
$ run/7z2john.pl test_*.7z
WARNING: unsupported coder with codec id '0x040109' in file 'test_1.7z' found.
WARNING: unsupported coder with codec id '0x020304' in file 'test_2.7z' found.
WARNING: unsupported coder with codec id '0x0b' in file 'test_3.7z' found.
WARNING: unsupported coder with codec id '0x0a' in file 'test_4.7z' found.
WARNING: unsupported coder with codec id '0x020302' in file 'test_5.7z' found.The codec IDs appear to correspond to:
| Codec ID | Method/filter |
|---|---|
| 0x040109 | Deflate64 |
| 0x020304 | Swap4 |
| 0x0b | RISC-V BCJ filter |
| 0x0a | ARM64 BCJ filter |
| 0x020302 | Swap2 |
It would be useful if 7z2john.pl could support these methods/filters when extracting hashes from encrypted 7z archives.
Source: openwall/john