Vesta Control Panel - Forum

Linux Passwords

Our password implementation relies on the Linux PAM authentication mechanism which employs MD5 hashing, to provide unique and secure passwords.

Security

The security of the MD5 hash function is severely compromised. A collision attack exists that can find collisions within seconds on a computer with a 2.6 GHz Pentium 4 processor (complexity of 224.1).[17] Further, there is also a chosen-prefix collision attack that can produce a collision for two inputs with specified prefixes within hours, using off-the-shelf computing hardware (complexity 239).[18] The ability to find collisions has been greatly aided by the use of off-the-shelf GPUs. On an NVIDIA GeForce 8400GS graphics processor, 16–18 million hashes per second can be computed. An NVIDIA GeForce 8800 Ultra can calculate more than 200 million hashes per second.[19]

These hash and collision attacks have been demonstrated in the public in various situations, including colliding document files[20][21] and digital certificates.[22] As of 2015, MD5 was demonstrated to be still quite widely used, most notably by security research and antivirus companies.[23]

MD5 for passwords

Using salted md5 for passwords is a bad idea. Not because of MD5's cryptographic weaknesses, but because it's fast. This means that an attacker can try billions of candidate passwords per second on a single GPU.

What you should use are deliberately slow hash constructions, such as scrypt, bcrypt and PBKDF2. Simple salted SHA-2 is not good enough because, like most general purpose hashes, it's fast. Check out How to securely hash passwords? for details on what you should use.