STIGQter: STIG Summary: Arista MLS EOS 4.X Router Security Technical Implementation Guide Version: 2 Release: 2 Benchmark Date: 02 Apr 2025:

The Arista router must be configured to drop all fragmented Internet Control Message Protocol (ICMP) packets destined to itself.

DISA Rule

SV-256017r882393_rule

Vulnerability Number

V-256017

Group Title

SRG-NET-000205-RTR-000002

Rule Version

ARST-RT-000350

Severity

CAT II

CCI(s)

• CCI-001097 - Monitor and control communications at the external managed interfaces to the system and at key managed interfaces within the system.

Weight

10

Fix Recommendation

Ensure all Arista routers have their receive path filter configured to drop all fragmented ICMP packets.

Step 1: Configure the ACL to filter the fragmented ICMP packets destined to itself.

LEAF-1A(config)#ip access-list ICMP_FRAGMENTS
LEAF-1A(config-acl-ICMP_FRAGMENTS)# 10 deny ip any any fragments
LEAF-1A(config-acl-ICMP_FRAGMENTS)# 20 permit ip any any
LEAF-1A(config-acl-ICMP_FRAGMENTS)# exit

Step 2: Apply the ACL to the external interfaces.

LEAF-1A(config)#interface ethernet 5
LEAF-1A(config-if-Et5)# ip access-group ICMP_FRAGMENTS in

Check Contents

Review the access control list (ACL) or filter for the Arista router receive path.

Verify it will drop all fragmented ICMP packets destined to itself.

Step 1: To verify the ACL is configured to filter the fragmented ICMP packets destined to itself, execute the command "sh ip access-list".

ip access-list ICMP_FRAGMENTS
10 deny ip any any fragments
20 permit ip any any

Step 2: To verify the ACL is applied to the external interfaces, execute the command "sh run int Eth YY".

interface ethernet 5
ip access-group ICMP_FRAGMENTS in

If the Arista router is not configured with a receive-path filter to drop all fragmented ICMP packets, this is a finding.

Note: If the platform does not support the receive path filter, verify all layer 3 interfaces have an ingress ACL to control what packets are allowed to be destined to the router for processing.

Vulnerability Number

V-256017

Documentable

False

Rule Version

ARST-RT-000350

Severity Override Guidance

Review the access control list (ACL) or filter for the Arista router receive path.

Verify it will drop all fragmented ICMP packets destined to itself.

Step 1: To verify the ACL is configured to filter the fragmented ICMP packets destined to itself, execute the command "sh ip access-list".

ip access-list ICMP_FRAGMENTS
10 deny ip any any fragments
20 permit ip any any

Step 2: To verify the ACL is applied to the external interfaces, execute the command "sh run int Eth YY".

interface ethernet 5
ip access-group ICMP_FRAGMENTS in

If the Arista router is not configured with a receive-path filter to drop all fragmented ICMP packets, this is a finding.

Note: If the platform does not support the receive path filter, verify all layer 3 interfaces have an ingress ACL to control what packets are allowed to be destined to the router for processing.

Check Content Reference

M

Target Key

5513