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1.5 CISC-RT-000130

Information

The Cisco router must be configured to restrict traffic destined to itself.

GROUP ID: V-216743RULE ID: SV-216743r531087

The route processor handles traffic destined to the router-the key component used to build forwarding paths and is instrumental with all network management functions. Hence, any disruption or DoS attack to the route processor can result in mission critical network outages.

NOTE: Nessus has provided the target output to assist in reviewing the benchmark to ensure target compliance.

Solution

Configure the ACL for any external interfaces as shown in the example.

RP/0/0/CPU0:R3(config)#ipv4 access-list EXTERNAL_ACL_INBOUNDRP/0/0/CPU0:R3(config-ipv4-acl)#permit tcp host x.11.1.1 eq bgp host x.11.1.2RP/0/0/CPU0:R3(config-ipv4-acl)#permit tcp host x.11.1.1 host x.11.1.2 eq bgpRP/0/0/CPU0:R3(config-ipv4-acl)#permit icmp host x.11.1.1 host x.11.1.2 echoRP/0/0/CPU0:R3(config-ipv4-acl)#permit icmp host x.11.1.1 host x.11.1.2 echo-replyRP/0/0/CPU0:R3(config-ipv4-acl)#deny ip any host x.11.1.1 logRP/0/0/CPU0:R3(config-ipv4-acl)#permit tcp any any established.........RP/0/0/CPU0:R3(config-ipv4-acl)#deny ip any any logRP/0/0/CPU0:R3(config-ipv4-acl)#exit

Configure the ACL for any external interfaces as shown in the example.

RP/0/0/CPU0:R3(config)#ipv4 access-list INTERNAL_ACL_INBOUNDRP/0/0/CPU0:R3(config-ipv4-acl)#permit icmp any anyRP/0/0/CPU0:R3(config-ipv4-acl)#permit ospf host 10.1.12.1 host 10.1.12.2RP/0/0/CPU0:R3(config-ipv4-acl)#permit tcp 10.2.1.0 0.0.0.255 host 10.1.12.2eq 22RP/0/0/CPU0:R3(config-ipv4-acl)#permit tcp 10.2.1.0 0.0.0.255 host 10.1.12.2eq tacacsRP/0/0/CPU0:R3(config-ipv4-acl)#permit udp 10.2.1.0 0.0.0.255 host 10.1.12.2 eq snmpRP/0/0/CPU0:R3(config-ipv4-acl)#permit udp 10.2.1.0 0.0.0.255 host 10.1.12.2 eq ntpRP/0/0/CPU0:R3(config-ipv4-acl)#deny ip any host 10.1.12.2 logRP/0/0/CPU0:R3(config-ipv4-acl)#permit ip any any
RP/0/0/CPU0:R3(config-ipv4-acl)#exit

Note: best practice is to configure the ACL statements relative to traffic destined to the router first followed by ACL statements for transit traffic.

Step 2: Apply the ACLs to the appropriate interface as shown in the example below.

RP/0/0/CPU0:R3(config)#int g0/0/0/1
RP/0/0/CPU0:R3(config-if)#ipv4 access-group EXTERNAL_ACL_INBOUND inRP/0/0/CPU0:R3(config-if)#exitRP/0/0/CPU0:R3(config)#int g0/0/0/2
RP/0/0/CPU0:R3(config-if)#ipv4 access-group INTERNAL_ACL_INBOUND in

See Also

https://workbench.cisecurity.org/benchmarks/23599

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7a., CAT|I, CCI|CCI-001097, Rule-ID|SV-216743r531087_rule, STIG-ID|CISC-RT-000130, Vuln-ID|V-216743

Plugin: Cisco

Control ID: 62dde17c6137766c6bdba1d1feb49e175a0b8739bb7274e8fbe37fc8846ce421