Detections
Analytics

1.425 OL09-00-006020

Information

OL 9 must ignore Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages.

GROUP ID: V-271864
RULE ID: SV-271864r1092304

ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack.

This feature of the IPv4 protocol has few legitimate uses. It should be disabled unless absolutely required.

Solution

Configure OL 9 to ignore IPv4 ICMP redirect messages.

Add or edit the following line in a single system configuration file in the "/etc/sysctl.d/" directory:

net.ipv4.conf.all.accept_redirects = 0

Load settings from all system configuration files with the following command:

$ sudo sysctl --system

See Also

https://workbench.cisecurity.org/benchmarks/27024

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b., CCI|CCI-000366, Rule-ID|SV-271864r1092304_rule, STIG-ID|OL09-00-006020, Vuln-ID|V-271864

Plugin: Unix

Control ID: 013fe2a565b155474b0d3dc72ef26e25a80667b44f8c853aee9f1d911f786d1e