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.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
high	V-233315	SRG-NET-000015-NAC-000090	FORE-NC-000070	SV-233315r1018662_rule	2024-12-19	2

Description
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.

Description

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.

ℹ️ Check
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.

ℹ️ Check

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
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.