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The Ubuntu operating system must not allow accounts configured with blank or null passwords.


Finding ID Version Rule ID IA Controls Severity
V-251507 UBTU-18-010523 SV-251507r832931_rule High
If an account has an empty password, anyone could log on and run commands with the privileges of that account. Accounts with empty passwords should never be used in operational environments.
Canonical Ubuntu 18.04 LTS Security Technical Implementation Guide 2022-12-06


Check Text ( C-54942r832929_chk )
To verify that null passwords cannot be used, run the following command:

$ grep nullok /etc/pam.d/common-password

If this produces any output, it may be possible to log on with accounts with empty passwords.

If null passwords can be used, this is a finding.
Fix Text (F-54896r832930_fix)
If an account is configured for password authentication but does not have an assigned password, it may be possible to log on to the account without authenticating.

Remove any instances of the "nullok" option in "/etc/pam.d/common-password" to prevent logons with empty passwords.