RHEL-10-800140 - RHEL 10 must prevent Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages from being accepted.

Information

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.

This feature of the IPv4 protocol has few legitimate uses. It must be disabled unless absolutely required.

Satisfies: SRG-OS-000420-GPOS-00186, SRG-OS-000142-GPOS-00077

Solution

Configure RHEL 10 to prevent IPv4 ICMP redirect messages from being accepted.

Create a configuration file if it does not already exist:

$ sudo vi /etc/sysctl.d/99-ipv4_accept_redirects.conf

Add the following line to the file:

net.ipv4.conf.default.accept_redirects = 0

Reload settings from all system configuration files with the following command:

$ sudo sysctl --system

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_RHEL_10_V1R1_STIG.zip

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-5, 800-53|SC-7(3), CAT|II, CCI|CCI-001101, CCI|CCI-002385, Rule-ID|SV-281346r1197251_rule, STIG-ID|RHEL-10-800140, Vuln-ID|V-281346

Plugin: Unix

Control ID: 85834603412a15d9de607383cb0609f15b2cf78e64caf925253ba48a8994166b