The NSX-T Tier-1 Gateway Firewall must deny network communications traffic by default and allow network communications traffic by exception (i.e., deny all, permit by exception).

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-251765	T1FW-3X-000021	SV-251765r810190_rule		Medium

Description
To prevent malicious or accidental leakage of traffic, organizations must implement a deny-by-default security posture at the network perimeter. Such rulesets prevent many malicious exploits or accidental leakage by restricting the traffic to only known sources and only those ports, protocols, or services that are permitted and operationally necessary. This configuration which is in the Manager function of the NSX-T implementation also helps prevent the firewall instance from failing to a state that may cause unauthorized access to make changes to the firewall filtering functions. As a managed boundary interface, the firewall must block all inbound and outbound network traffic unless a filter is installed to explicitly allow it. The allow filters must comply with the Ports, Protocols, and Services Management (PPSM) Category Assurance List (CAL) and Vulnerability Assessment (VA). Satisfies: SRG-NET-000235-FW-000133, SRG-NET-000236-FW-000027

Description

To prevent malicious or accidental leakage of traffic, organizations must implement a deny-by-default security posture at the network perimeter. Such rulesets prevent many malicious exploits or accidental leakage by restricting the traffic to only known sources and only those ports, protocols, or services that are permitted and operationally necessary. This configuration which is in the Manager function of the NSX-T implementation also helps prevent the firewall instance from failing to a state that may cause unauthorized access to make changes to the firewall filtering functions. As a managed boundary interface, the firewall must block all inbound and outbound network traffic unless a filter is installed to explicitly allow it. The allow filters must comply with the Ports, Protocols, and Services Management (PPSM) Category Assurance List (CAL) and Vulnerability Assessment (VA). Satisfies: SRG-NET-000235-FW-000133, SRG-NET-000236-FW-000027

STIG	Date
VMware NSX-T Tier 1 Gateway Firewall Security Technical Implementation Guide	2022-09-01

Details

Check Text ( C-55202r810188_chk )
From the NSX-T Manager web interface, go to Security >> Gateway Firewall >> Gateway Specific Rules >> Choose each Tier-1 Gateway in drop-down >> Policy_Default_Infra Section >> Action. If the default_rule is set to Allow, this is a finding.

Fix Text (F-55156r810189_fix)
From the NSX-T Manager web interface, go to Security >> Gateway Firewall >> Gateway Specific Rules >> Choose each Tier-1 Gateway in drop-down >> Policy_Default_Infra Section >> Action >> change the Action to Drop or Reject and click Publish.