Title

The Deny log on through Terminal Services user right on member servers must be configured to prevent access from highly privileged domain accounts and local administrator accounts on domain systems and unauthenticated access on all systems. (Cat II impact)

Discussion

Inappropriate granting of user rights can provide system, administrative, and other high level capabilities. The "Deny log on through Terminal Services" right defines the accounts that are prevented from logging on using Terminal Services. In an Active Directory Domain, denying logons to the Enterprise Admins and Domain Admins groups on lower trust systems helps mitigate the risk of privilege escalation from credential theft attacks which could lead to the compromise of an entire domain. Local administrator accounts on domain-joined systems must also be assigned this right to decrease the risk of lateral movement resulting from credential theft attacks. The Guests group must be assigned this right to prevent unauthenticated access.

Check Content

Analyze the system using the Security Configuration and Analysis snap-in. Expand the Security Configuration and Analysis tree view. Navigate to Local Policies -> User Rights Assignment. If the following accounts or groups are not defined for the "Deny log on through Terminal Services" right, this is a finding: Domain Systems Only: Enterprise Admins group Domain Admins group *All Local Administrator Accounts using the "DenyNetworkAccess" or "DeniedNetworkAccess" group (see V-45589). Do not use the built-in Administrators group. This group must contain the appropriate accounts/groups responsible for administering the system. All Systems: Guests group *Documentation and scripts supporting the use of this group to restrict local administrative accounts were changed at one point. The original name, "DeniedNetworkAccess", was changed to "DenyNetworkAccess". Automated benchmarks will look for either of these groups. Use of other methods will require manual validation.

Fix Text

Configure the policy value for Computer Configuration -> Windows Settings -> Security Settings -> Local Policies -> User Rights Assignment -> "Deny log on through Terminal Services" to include the following. Domain Systems Only: Enterprise Admins group Domain Admins group *All Local Administrator Accounts using the "DenyNetworkAccess" or "DeniedNetworkAccess" group (see V-45589). Do not use the built-in Administrators group. This group must contain the appropriate accounts/groups responsible for administering the system. All Systems: Guests group *Documentation and scripts supporting the use of this group to restrict local administrative accounts were changed at one point. The original name, "DeniedNetworkAccess", was changed to "DenyNetworkAccess". Automated benchmarks will look for either of these groups. Use of other methods will require manual validation.

Additional Identifiers

Rule ID: SV-47142r3_rule

Vulnerability ID: V-26486

Group Title: Deny log on through Remote Desktop \ Terminal Services

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.