Detections
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1.53 CISC-RT-000730

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Information

The Cisco PE switch must be configured to block any traffic that is destined to the IP core infrastructure.

GROUP ID: V-221126
RULE ID: SV-221126r999735

IP/MPLS networks providing VPN and transit services must provide, at the least, the same level of protection against denial-of-service (DoS) attacks and intrusions as Layer 2 networks. Although the IP core network elements are hidden, security should never rely entirely on obscurity.

IP addresses can be guessed. Core network elements must not be accessible from any external host. Protecting the core from any attack is vital for the integrity and privacy of customer traffic as well as the availability of transit services. A compromise of the IP core can result in an outage or, at a minimum, non-optimized forwarding of customer traffic. Protecting the core from an outside attack also prevents attackers from using the core to attack any customer. Hence, it is imperative that all switches at the edge deny traffic destined to any address belonging to the IP core infrastructure.

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

Solution

Configure protection for the IP core to be implemented at the edges by blocking any traffic with a destination address assigned to the IP core infrastructure.

Step 1 : Configure an ingress ACL to discard and log packets destined to the IP core address space.

SW1(config)# ip access-list BLOCK_TO_CORE
SW1(config-acl)# deny ip any 10.1.x.0 0.0.255.255 log
SW1(config-acl)# exit

Step 2 : Apply the ACL inbound to all external or CE-facing interfaces.

SW1(config)#int e1/2
SW1(config-if)# ip access-group BLOCK_TO_CORE in
SW1(config-if)# end

See Also

https://workbench.cisecurity.org/benchmarks/22581

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-7a., CAT|I, CCI|CCI-001097, CSCv7|13.3, Rule-ID|SV-221126r999735_rule, STIG-ID|CISC-RT-000730, Vuln-ID|V-221126

Plugin: Cisco

Control ID: b18130f1a3d18cd259b6032d1b62c89ac9f96635d3bf2972b242f0dd95c97a46