Check: SLES-15-020010
SUSE Linux Enterprise Server 15 STIG:
SLES-15-020010
(in versions v1 r13 through v1 r1)
Title
The SUSE operating system must lock an account after three consecutive invalid access attempts. (Cat II impact)
Discussion
By limiting the number of failed access 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. The pam_tally2.so module maintains a count of attempted accesses. This includes user name entry into a logon field as well as password entry. With counting access attempts, it is possible to lock an account without presenting a password into the password field. This should be taken into consideration as it poses as an avenue for denial of service. Satisfies: SRG-OS-000021-GPOS-00005, SRG-OS-000329-GPOS-00128
Check Content
Verify the SUSE operating system locks a user account after three consecutive failed access attempts until the locked account is released by an administrator. Check that the system locks a user account after three consecutive failed login attempts using the following command: > grep pam_tally2.so /etc/pam.d/common-auth auth required pam_tally2.so onerr=fail deny=3 If no line is returned or the line is commented out, this is a finding. If the line is missing "onerr=fail", this is a finding. If the line has "deny" set to a value other than 1, 2, or 3, this is a finding. Check that the system resets the failed login attempts counter after a successful login using the following command: > grep pam_tally2.so /etc/pam.d/common-account account required pam_tally2.so If the account option is missing, or commented out, this is a finding.
Fix Text
Configure the operating system to lock an account when three unsuccessful access attempts occur. Modify the first line of the auth section "/etc/pam.d/common-auth" file to match the following lines: auth required pam_tally2.so onerr=fail silent audit deny=3 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 "pam-config" program. The "pam-config" program should not be used to update the configurations listed in this requirement.
Additional Identifiers
Rule ID: SV-234867r854212_rule
Vulnerability ID: V-234867
Group Title: SRG-OS-000021-GPOS-00005
Expert Comments
CCIs
| Number | Definition |
|---|---|
| CCI-000044 |
The information system enforces the organization-defined limit of consecutive invalid logon attempts by a user during the organization-defined time period. |
| CCI-002238 |
The information system automatically locks the account or node for either an organization-defined time period, until the locked account or node is released by an administrator, or delays the next logon prompt according to the organization-defined delay algorithm when the maximum number of unsuccessful logon attempts is exceeded. |
Controls
| Number | Title |
|---|---|
| AC-7 |
Unsuccessful Logon Attempts |