Accounts on the SUSE operating system that are subject to three unsuccessful logon attempts within 15 minutes must be locked for the maximum configurable period.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-81709	SLES-12-010131	SV-96423r3_rule		Medium

Description
By limiting the number of failed logon attempts, the risk of unauthorized system access via user password guessing, otherwise known as brute-forcing, is reduced. Limits are imposed by locking the account. Satisfies: SRG-OS-000329-GPOS-00128, SRG-OS-000021-GPOS-00005

STIG	Date
SLES 12 Security Technical Implementation Guide	2020-06-30

Details

Check Text ( C-81489r3_chk )
Verify the operating system automatically locks an account for the maximum period for which the system can be configured. Check that the system locks an account for the maximum period after three unsuccessful logon attempts within a period of 15 minutes with the following command: # grep pam_tally2.so /etc/pam.d/common-auth auth required pam_tally2.so preauth silent audit deny=3 even_deny_root fail_interval=900 unlock_time=900 auth [default=die] pam_tally2.so authfail audit deny=3 even_deny_root fail_interval=900 unlock_time=900 If the "unlock_time" parameter is not set to "0", "never", or is set to a value less than "900" on both "auth" lines with the "pam_tally2.so" module, or is missing from these lines, this is a finding. Note: The maximum configurable value for "unlock_time" is "604800". Verify that "pam_tally2.so" is configured for all accounts: # grep pam_tally2.so /etc/pam.d/common-account account required pam_tally2.so If the above line is missing or is commented out, this is a finding.

Check Text ( C-81489r3_chk )

Verify the operating system automatically locks an account for the maximum period for which the system can be configured.

Check that the system locks an account for the maximum period after three unsuccessful logon attempts within a period of 15 minutes with the following command:

# grep pam_tally2.so /etc/pam.d/common-auth
auth required pam_tally2.so preauth silent audit deny=3 even_deny_root fail_interval=900 unlock_time=900
auth [default=die] pam_tally2.so authfail audit deny=3 even_deny_root fail_interval=900 unlock_time=900

If the "unlock_time" parameter is not set to "0", "never", or is set to a value less than "900" on both "auth" lines with the "pam_tally2.so" module, or is missing from these lines, this is a finding.
Note: The maximum configurable value for "unlock_time" is "604800".

Verify that "pam_tally2.so" is configured for all accounts:

# grep pam_tally2.so /etc/pam.d/common-account
account required pam_tally2.so

If the above line is missing or is commented out, this is a finding.

Fix Text (F-88557r4_fix)
Configure the operating system to lock an account for the maximum period when three unsuccessful logon attempts in 15 minutes are made. Modify the first three lines of the auth section "/etc/pam.d/common-auth" file to match the following lines: auth required pam_tally2.so preauth silent audit deny=3 even_deny_root fail_interval=900 unlock_time=900 auth sufficient pam_unix.so try_first_pass auth [default=die] pam_tally2.so authfail audit deny=3 even_deny_root fail_interval=900 unlock_time=900 Add or modify the following line in the /etc/pam.d/common-account file: account required pam_tally2.so Note: Manual changes to the listed files may be overwritten by the "authconfig" program. The "authconfig" program should not be used to update the configurations listed in this requirement.

Fix Text (F-88557r4_fix)

Configure the operating system to lock an account for the maximum period when three unsuccessful logon attempts in 15 minutes are made.

Modify the first three lines of the auth section "/etc/pam.d/common-auth" file to match the following lines:

auth required pam_tally2.so preauth silent audit deny=3 even_deny_root fail_interval=900 unlock_time=900
auth sufficient pam_unix.so try_first_pass
auth [default=die] pam_tally2.so authfail audit deny=3 even_deny_root fail_interval=900 unlock_time=900

Add or modify the following line in the /etc/pam.d/common-account file:
account required pam_tally2.so

Note: Manual changes to the listed files may be overwritten by the "authconfig" program. The "authconfig" program should not be used to update the configurations listed in this requirement.