The OS X system must not accept source-routed IPv4 packets.

From Apple OS X 10.12 Security Technical Implementation Guide

Associated with: CCI-000366

SV-90957r1_rule The OS X system must not accept source-routed IPv4 packets.

Vulnerability discussion

A source-routed packet attempts to specify the network path the packet should take. If the system is not configured to block the incoming source-routed packets, an attacker can redirect the system's network traffic. Configuring the system to drop incoming source-routed IPv4 packets mitigates this risk.

Check content

To check if the system is configured to accept "source-routed" packets, run the following command: sysctl net.inet.ip.accept_sourceroute If the value is not "0", this is a finding.

Fix text

To configure the system to not accept "source-routed" packets, add the following line to "/etc/sysctl.conf", creating the file if necessary: net.inet.ip.accept_sourceroute=0

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