The system must ignore IPv4 ICMP redirect messages.

From MAC OSX 10.6 Workstation Security Technical Implementation Guide

Associated with IA controls: ECSC-1

SV-38204r1_rule The system must ignore IPv4 ICMP redirect messages.

Vulnerability discussion

ICMP redirect messages are used by routers to inform hosts of a more direct route existing 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.

Check content

Open a terminal session and enter the following command to view the value of "net.inet.icmp.drop_redirect". sysctl -a | grep net.inet.icmp.drop_redirect If the value of "net.inet.icmp.drop_redirect" is not set to "0", this is a finding.

Fix text

Open a terminal session and edit the /etc/sysctl.conf file and add the following line. net.inet.icmp.drop_redirect=0 NOTE: If the sysctl.conf file does not exist use the following command to create one. touch /etc/sysctl.conf

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