Title

Forescout appliance must not be configured to implement a DHCP layer 3 method for separation or device authorization. This is required for compliance with C2C Step 2. (Cat I impact)

Discussion

Using DHCP, an internal rogue device can still bypass the authentication process, regardless of the policy flow. Older version of the ForeScout may have a setting to support DHCP for NAC authorization. This capability should not be used. The DHCP Classifier Plugin allows Forescout to view and use DHCP properties that can be used to improve classification of uncategorized devices obtained from DHCP-enabled network-connected devices. However, DHCP should not be used as the primary authentication method on the NAC.

Check Content

If DOD is not at C2C Step 1 or higher, this is not a finding. If the Cisco ISE version does not have the capability to configure DHCP for authorizing access, this is not applicable. Check Forescout policy and verify it is not configured to use the DHCP protocol for device authentication or authorization for network access requests. If the NAC is configured to use the DHCP protocol for device authentication or authorization for network access requests, this is a finding.

Fix Text

If the NAC software version has the capability to configure the DHCP protocol for device authentication or authorization for network access requests: 1. Log on to the Forescout UI. 2. Locate the Authentication & Authorization policy. 3. Disable DHCP if used.

Additional Identifiers

Rule ID: SV-233315r1018662_rule

Vulnerability ID: V-233315

Group Title: SRG-NET-000015-NAC-000090

Expert Comments

CCIs tied to check.

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