SLEM 5 must not allow interfaces to accept Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages by default.

An XCCDF Rule

Description

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.

ID: SV-261316r996418_rule
Version: SLEM-05-253025
Severity: Medium
References: CCI-000366
Updated: 5 days ago

Remediation Templates

Configure SLEM 5 to not accept IPv4 ICMP redirect messages by default by running the following command as an administrator:

     > sudo sysctl -w net.ipv4.conf.default.accept_redirects=0

If "0" is not the system's default value, add or update the following line in "/etc/sysctl.d/99-stig.conf":
     > sudo sh -c 'echo "net.ipv4.conf.default.accept_redirects=0" >> /etc/sysctl.d/99-stig.conf'

     > sudo sysctl --system

SLEM 5 must not allow interfaces to accept Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages by default.

Description

Remediation Templates

A Manual Procedure