The system must ignore IPv4 ICMP redirect messages.

From HP-UX 11.31 Security Technical Implementation Guide

Associated with IA controls: ECSC-1

SV-29719r1_rule The system must ignore IPv4 ICMP redirect messages.

Vulnerability discussion

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.

Check content

Determine if the system is configured to block inbound IPv4 ICMP redirect messages. # ipfstat -i Examine the list for a rule such as: block in quick proto icmp from any to any icmp-type redir If the listed rules do not block inbound IPv4 ICMP redirect messages, this is a finding.

Fix text

Edit /etc/opt/ipf/ipf.conf and add rules to block incoming IPv4 ICMP redirect messages, such as: block in quick proto icmp from any to any icmp-type redir Reload the IPF rules. Flush the rules from your ruleset using the -Fa option. The -A option specifies the active rules list. The -f option specifies the rules configuration file to be used: # ipf -Fa -A -f /etc/opt/ipf/ipf.conf

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