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5.4.1.8 Ensure minimum number of hashing rounds is configured

Information

When ENCRYPT_METHOD is set to SHA256 or SHA512, the SHA_CRYPT_MIN_ROUNDS and SHA_CRYPT_MAX_ROUNDS parameters define the number of SHA rounds used by the encryption algorithm by default when the number of rounds is not specified on the command line.

With a lot of rounds, it is more difficult to brute force the password. But note also that more CPU resources will be needed to authenticate users.

If not specified, the libc will choose the default number of rounds (5000), which is orders of magnitude too low for modern hardware.

The values must be inside the 1000-999,999,999 range.

If only one of the SHA_CRYPT_MIN_ROUNDS or SHA_CRYPT_MAX_ROUNDS values is set, then this value will be used.

If SHA_CRYPT_MIN_ROUNDS > SHA_CRYPT_MAX_ROUNDS, the highest value will be used.

Note: This parameter 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 system must use a strong hashing algorithm to store the password. The system must use a sufficient number of hashing rounds to ensure the required level of entropy.

Passwords need to be protected at all times, and encryption is the standard method for protecting passwords. If passwords are not encrypted, they can be plainly read (i.e., clear text) and easily compromised.

Solution

Edit /etc/login.defs and add of modify the line containing SHA_CRYPT_MIN_ROUNDS :

Example:

SHA_CRYPT_MIN_ROUNDS 5000

Impact:

A large number of rounds requires more CPU resources to authenticate users

See Also

https://workbench.cisecurity.org/benchmarks/19886

Item Details

Category: IDENTIFICATION AND AUTHENTICATION

References: 800-53|IA-5, CAT|II, CSCv7|16.4, Rule-ID|SV-230233r880705_rule, STIG-ID|RHEL-08-010130, Vuln-ID|V-230233

Plugin: Unix

Control ID: 68050f17107ad4e0abda3483c64ff7af498b10f22a644cfc6a2379e493edda04