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 have Internet Control Message Protocol (ICMP) mask replies disabled on all external interfaces.

DISA Rule

SV-256033r882441_rule

Vulnerability Number

V-256033

Group Title

SRG-NET-000362-RTR-000114

Rule Version

ARST-RT-000540

Severity

CAT II

CCI(s)

• CCI-002385 - Protect against or limit the effects of organization-defined types of denial of service events.

Weight

10

Fix Recommendation

Step 1: Disable ICMP mask replies on all external interfaces.

ip access-group DENY_ICMP_MASK_REPLY
deny icmp any any mask-reply
permit ip any any

Step 2: Apply the ACL outbound on interfaces.

interface Ethernet 2
ip access-group DENY_ICMP_MASK_REPLY out

Check Contents

Review the Arista device configuration to determine if controls have been defined to ensure the router does not send ICMP Mask Reply messages out to any external interfaces.

EOS by default does not respond to ICMP Type 17 or 18.

Step 1: To verify the ACL is configured to determine the router does not send ICMP Mask Reply messages out to any external interfaces, execute the command "sh ip access-list".

ip access-group DENY_ICMP_MASK_REPLY
deny icmp any any mask-reply
permit ip any any

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

interface Ethernet 2
ip access-group DENY_ICMP_MASK_REPLY out

If ICMP Mask Reply messages are enabled on any external interfaces, this is a finding.

Vulnerability Number

V-256033

Documentable

False

Rule Version

ARST-RT-000540

Severity Override Guidance

Review the Arista device configuration to determine if controls have been defined to ensure the router does not send ICMP Mask Reply messages out to any external interfaces.

EOS by default does not respond to ICMP Type 17 or 18.

Step 1: To verify the ACL is configured to determine the router does not send ICMP Mask Reply messages out to any external interfaces, execute the command "sh ip access-list".

ip access-group DENY_ICMP_MASK_REPLY
deny icmp any any mask-reply
permit ip any any

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

interface Ethernet 2
ip access-group DENY_ICMP_MASK_REPLY out

If ICMP Mask Reply messages are enabled on any external interfaces, this is a finding.

Check Content Reference

M

Target Key

5513