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V-251753

CAT II (Medium)

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

Rule ID

SV-251753r856694_rule

STIG

VMware NSX-T Tier-0 Gateway RTR Security Technical Implementation Guide

Version

V1R2

CCIs

CCI-002385

Discussion

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. Host unreachable ICMP messages are commonly used by attackers for network mapping and diagnosis.

Check Content

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 Firewall rule to verify one exists to drop ICMP unreachable messages.

If a rule does not exist to drop ICMP unreachable messages, this is a finding.

Fix Text

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 Destination Unreachable", and then click "Apply".

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

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