Vulnerability Discussion

Source-routed packets allow the source of the packet to suggest that routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routed traffic, such as when IPv4 forwarding is enabled and the system is functioning as a router.

Check

Verify the SUSE operating system does not accept IPv4 source-routed packets by default.

Check the value of the default accept source route variable with the following command:

# sysctl net.ipv4.conf.default.accept_source_route
net.ipv4.conf.default.accept_source_route = 0

If the returned line does not have a value of "0" this is a finding.

Fix

Configure the SUSE operating system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" (or modify the line to have the required value):

net.ipv4.conf.default.accept_source_route = 0

Run the following command to apply this value:

# sysctl --system