5.4.1.4 Ensure strong password hashing algorithm is configured

Information

A cryptographic hash function converts an arbitrary-length input into a fixed length output. Password hashing performs a one-way transformation of a password, turning the password into another string, called the hashed password.

ENCRYPT_METHOD (string) - This defines the system default encryption algorithm for encrypting passwords (if no algorithm are specified on the command line). It can take one of these values:

- MD5 - MD5-based algorithm will be used for encrypting password
- SHA256 - SHA256-based algorithm will be used for encrypting password
- SHA512 - SHA512-based algorithm will be used for encrypting password
- BCRYPT - BCRYPT-based algorithm will be used for encrypting password
- YESCRYPT - YESCRYPT-based algorithm will be used for encrypting password
- DES - DES-based algorithm will be used for encrypting password (default)

Note:

- This parameter overrides the deprecated MD5_CRYPT_ENAB variable.
- This parameter will only affect the generation of group passwords.
- The generation of user passwords is done by PAM and subject to the PAM configuration.
- It is recommended to set this variable consistently with the PAM configuration.

The SHA-512 and yescrypt algorithms provide a stronger hash than other algorithms used by Linux for password hash generation. A stronger hash provides additional protection to the system by increasing the level of effort needed for an attacker to successfully determine local group passwords.

Solution

Edit /etc/login.defs and set the ENCRYPT_METHOD to SHA512 or YESCRYPT :

ENCRYPT_METHOD <HASHING_ALGORITHM>

Example:

ENCRYPT_METHOD YESCRYPT

Note:

- This only effects local groups' passwords created after updating the file to use sha512 or yescrypt
- If it is determined that the password algorithm being used is not sha512 or yescrypt once it is changed, it is recommended that all group passwords be updated to use the stronger hashing algorithm.
- It is recommended that the chosen hashing algorithm is consistent across /etc/login.defs and the PAM configuration

See Also

https://workbench.cisecurity.org/benchmarks/18208

Item Details

Category: IDENTIFICATION AND AUTHENTICATION, SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|IA-5(1), 800-53|SC-28, 800-53|SC-28(1), CSCv7|16.4

Plugin: Unix

Control ID: cd83087100a8b59eb8f243c26de62681422be974d7f99150744adf4a0971be3b