3.1.1 Ensure packet redirect sending is disabled

Information

ICMP Redirects are used to send routing information to other hosts. As a host itself does not act as a router (in a host only configuration), there is no need to send redirects.

Rationale:

An attacker could use a compromised host to send invalid ICMP redirects to other router devices in an attempt to corrupt routing and have users access a system set up by the attacker as opposed to a valid system.

Solution

Run the following command to set the active kernel parameters and persist the settings:

# apiclient apply <<EOF
[settings.kernel.sysctl]
"net.ipv4.conf.all.send_redirects" = "0"
"net.ipv4.conf.default.send_redirects" = "0"
EOF

Run the following command to flush the routing cache:

# sysctl -w net.ipv4.route.flush=1

See Also

https://workbench.cisecurity.org/benchmarks/6709

Item Details

Category: CONFIGURATION MANAGEMENT, SYSTEM AND SERVICES ACQUISITION

References: 800-53|CM-1, 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|CM-7(1), 800-53|CM-9, 800-53|SA-3, 800-53|SA-8, 800-53|SA-10, CSCv7|5.1

Plugin: Unix

Control ID: 7ba6353285a8f58dff78fd928ac6e357e512a39cc8a02a62d520e843beecb66e