5.4.1 Ensure password creation requirements are configured - 'minlen'

Information

The pam_pwquality.so module checks the strength of passwords. It performs checks such as making sure a password is not a dictionary word, it is a certain length, contains a mix of characters (e.g. alphabet, numeric, other) and more. The following are definitions of the pam_pwquality.so options.

The following options are set in the /etc/security/pwquality.conf file:

Password Length:

minlen = 14 - password must be 14 characters or more

Password complexity:

minclass = 4 - The minimum number of required classes of characters for the new password (digits, uppercase, lowercase, others)

OR

dcredit = -1 - provide at least one digit

ucredit = -1 - provide at least one uppercase character

ocredit = -1 - provide at least one special character

lcredit = -1 - provide at least one lowercase character

The following is st in the /etc/pam.d/common-password file:

retry=3 - Allow 3 tries before sending back a failure. The settings shown above are one possible policy. Alter these values to conform to your own organization's password policies.

Rationale:

Strong passwords protect systems from being hacked through brute force methods.

Solution

Run the following command to install the pam_pwquality module:

apt install libpam-pwquality

Edit the file /etc/security/pwquality.conf and add or modify the following line for password length to conform to site policy

minlen = 14

Edit the file /etc/security/pwquality.conf and add or modify the following line for password complexity to conform to site policy

minclass = 4

OR

dcredit = -1
ucredit = -1
ocredit = -1
lcredit = -1

Edit the /etc/pam.d/common-password file to include the appropriate options for pam_pwquality.so and to conform to site policy:

password requisite pam_pwquality.so retry=3

Additional Information:

Additional module options may be set, recommendation requirements only cover including try_first_pass and minlen set to 14 or more.

Settings in /etc/security/pwquality.conf must use spaces around the = symbol.

See Also

https://workbench.cisecurity.org/files/3208