The NSX-T Tier-0 Gateway must be configured to have Internet Control Message Protocol (ICMP) redirects disabled on all external interfaces.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-251755	T0RT-3X-000066	SV-251755r856696_rule		Medium

Description
The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Redirect ICMP messages are commonly used by attackers for network mapping and diagnosis.

STIG	Date
VMware NSX-T Tier-0 Gateway RTR Security Technical Implementation Guide	2022-09-01

Details

Check Text ( C-55192r810147_chk )
If the Tier-0 Gateway is deployed in an Active/Active HA mode, this is Not Applicable. From the NSX-T Manager web interface, go to Security >> Gateway Firewall >> Gateway Specific Rules, and choose each Tier-0 Gateway in the drop-down. Review each Tier-0 Gateway Firewalls rules to verify one exists to drop ICMP redirects. If a rule does not exist to drop ICMP redirects, this is a finding.

Fix Text (F-55146r810148_fix)
To configure a shared rule to drop ICMP unreachable messages do the following: From the NSX-T Manager web interface, go to Security >> Gateway Firewall >> All Shared Rules. Click "Add Rule" (Add a policy first if needed), under services select "ICMP Redirect", and then click "Apply". Enable logging, under the "Applied To" field select the target Tier-0 Gateways, and then click "Publish" to enforce the new rule. Note: A rule can also be created under Gateway Specific Rules to meet this requirement.

Fix Text (F-55146r810148_fix)

To configure a shared rule to drop ICMP unreachable messages do the following:

From the NSX-T Manager web interface, go to Security >> Gateway Firewall >> All Shared Rules.

Click "Add Rule" (Add a policy first if needed), under services select "ICMP Redirect", and then click "Apply".

Enable logging, under the "Applied To" field select the target Tier-0 Gateways, and then click "Publish" to enforce the new rule.

Note: A rule can also be created under Gateway Specific Rules to meet this requirement.