STIGQter: STIG Summary: Cisco NX-OS Switch RTR Security Technical Implementation Guide Version: 2 Release: 1 Benchmark Date: 23 Apr 2021:

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

DISA Rule

SV-221081r622190_rule

Vulnerability Number

V-221081

Group Title

SRG-NET-000205-RTR-000002

Rule Version

CISC-RT-000140

Severity

CAT II

CCI(s)

• CCI-001097 - The information system monitors and controls communications at the external boundary of the information system and at key internal boundaries within the system.

Weight

10

Fix Recommendation

Configure the external and internal ACLs to drop all fragmented ICMP packets destined to itself as shown in the example below:

SW1(config)# ip access-list EXTERNAL_ACL
SW1(config-acl)# 35 deny icmp any host x.11.1.2 fragments log
SW1(config-acl)# exit

SW1(config)# ip access-list INTERNAL_ACL
SW1(config-acl)# 25 deny icmp any host 10.1.12.2 fragments log
SW1(config-acl)# end

Note: Ensure the above statement is before any permit statements for ICMP.

Check Contents

Review the external and internal ACLs to verify that the switch is configured drop all fragmented ICMP packets destined to itself.

ip access-list EXTERNAL_ACL
10 permit tcp x.11.1.1/32 eq bgp x.11.1.2/32
20 permit tcp x.11.1.1/32 x.11.1.2/32 eq bgp
30 deny icmp any x.11.1.2/32 fragments log
40 permit icmp x.11.1.1/32 x.11.1.2/32 echo
…
…
…
90 deny ip any any log

ip access-list INTERNAL_ACL
10 deny icmp any host 10.1.12.2/32 fragments
20 permit icmp any any

Note: Ensure the statement to deny ICMP fragments is before any permit statements for ICMP.

If the switch is not configured to drop all fragmented ICMP packets destined to itself, this is a finding.

Vulnerability Number

V-221081

Documentable

False

Rule Version

CISC-RT-000140

Severity Override Guidance

Review the external and internal ACLs to verify that the switch is configured drop all fragmented ICMP packets destined to itself.

ip access-list EXTERNAL_ACL
10 permit tcp x.11.1.1/32 eq bgp x.11.1.2/32
20 permit tcp x.11.1.1/32 x.11.1.2/32 eq bgp
30 deny icmp any x.11.1.2/32 fragments log
40 permit icmp x.11.1.1/32 x.11.1.2/32 echo
…
…
…
90 deny ip any any log

ip access-list INTERNAL_ACL
10 deny icmp any host 10.1.12.2/32 fragments
20 permit icmp any any

Note: Ensure the statement to deny ICMP fragments is before any permit statements for ICMP.

If the switch is not configured to drop all fragmented ICMP packets destined to itself, this is a finding.

Check Content Reference

M

Target Key

4075

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