Zyxel password decrypter

This small tool has the purpose of allowing the decryption of all the passwords contained in the configuration files of the Zyxel security devices (ZyWALL, USG, etc).

The tool takes a configuration file as input and takes care of decrypting all the lines that contain the strings $4$ and $5$.

Tests were performed on firmware versions 4.7x, 5.0 and 5.1.

A detailed description on how the tool works and the process of its creation can be found at https://security.humanativaspa.it/zyxel-firmware-extraction-and-password-analysis

If you wish you can contact me at @0x696e6f6465