Title

The system must ignore IPv4 ICMP redirect messages. (Cat II impact)

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 the type of zone that you are currently securing. # zonename If the zone is not the global zone, determine if any interfaces are exclusive to the zone: # dladm show-link If the output indicates "insufficient privileges" then this requirement is not applicable. If the zone is the global zone or the non-global zone has exclusive interfaces verify the system does not accept IPv4 ICMP redirect messages. Procedure: # ndd -get /dev/ip ip_ignore_redirect If the result is not 1, this is a finding.

Fix Text

Configure the system to not accept IPv4 ICMP redirect messages. Procedure: # ndd -set /dev/ip ip_ignore_redirect 1 This command must also be added to a system startup script.

Additional Identifiers

Rule ID: SV-226897r603265_rule

Vulnerability ID: V-226897

Group Title: SRG-OS-000480

Expert Comments

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