The network device must log all interface access control lists (ACL) deny statements.

From Firewall Security Technical Implementation Guide - Cisco

Part of Interface ACL deny statements are not logged.

Associated with IA controls: ECSC-1, ECAT-2, ECAT-1

SV-50941r1_rule The network device must log all interface access control lists (ACL) deny statements.

Vulnerability discussion

Auditing and logging are key components of any security architecture. It is essential for security personnel to know what is being done, attempted to be done, and by whom in order to compile an accurate risk assessment. Auditing the actions on network devices provides a means to recreate an attack, or identify a configuration mistake on the device.

Check content

Review the network device interface ACLs to verify all deny statements are logged. interface GigabitEthernet0/0 description To Outside Router nameif outside security-level 0 ip address 173.x.x.x 255.x.x.x ipv6 nd suppress-ra access-group outside_access_in in interface outside ... access-list outside_access_in extended deny ip 172.16.0.0 255.240.0.0 any log access-list outside_access_in extended deny ip 10.0.0.0 255.0.0.0 any log access-list outside_access_in extended deny ip 192.168.0.0 255.255.0.0 any log access-list outside_access_in extended deny ip 127.0.0.0 0.0.0.0 any log ... access-list outside_access_in extended deny ip any any log

Fix text

Configure interface ACLs to log all deny statements.

Pro Tips

Lavender hyperlinks in small type off to the right (of CSS class id, if you view the page source) point to globally unique URIs for each document and item. Copy the link location and paste anywhere you need to talk unambiguously about these things.

You can obtain data about documents and items in other formats. Simply provide an HTTP header Accept: text/turtle or Accept: application/rdf+xml.