Detections
Analytics

1.430 OL09-00-006025

Information

OL 9 must prevent IPv4 Internet Control Message Protocol (ICMP) redirect messages from being accepted.

GROUP ID: V-271869
RULE ID: SV-271869r1092319

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 must be disabled unless absolutely required.

Solution

Configure OL 9 to prevent IPv4 ICMP redirect messages from being accepted.

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

net.ipv4.conf.default.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-271869r1092319_rule, STIG-ID|OL09-00-006025, Vuln-ID|V-271869

Plugin: Unix

Control ID: ef2ea8716d7c2f683f7e8b7adeb555ffac9cd4023e3b4edbe191e97e82f24aa2