The Ubuntu operating system must automatically lock an account until the locked account is released by an administrator when three unsuccessful logon attempts.

From Canonical Ubuntu 16.04 LTS Security Technical Implementation Guide

SV-90167r2_rule The Ubuntu operating system must automatically lock an account until the locked account is released by an administrator when three unsuccessful logon attempts.

Vulnerability discussion

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-000021-GPOS-00005, SRG-OS-000329-GPOS-00128

Check content

Verify the Ubuntu operating system automatically locks an account until the account lock is released by an administrator when three unsuccessful logon attempts are made. Check that the Ubuntu operating system automatically locks an account after three unsuccessful attempts with the following command: # grep pam_tally /etc/pam.d/common-auth auth required pam_tally2.so onerr=fail deny=3 If "onerr=fail deny=3" is not used in "/etc/pam.d/common-auth" or is called with "unlock_time", this is a finding.

Fix text

Configure the Ubuntu operating system to automatically lock an account until the locked account is released by an administrator when three unsuccessful logon attempts are made by appending the following line to the "/etc/pam.d/common-auth file": "auth required pam_tally2.so onerr=fail deny=3"

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