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RHEL-10-800170 RHEL 10 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.

DISA STIG library V1R3
All changes in this version
first version loaded CAT II

Maps to SC-5 via CCI-002385, CCI-001104

Title

RHEL 10 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.

Control

Verify RHEL 10 ignores ICMP echoes sent to a broadcast address. Check the value of the "net.ipv4.icmp_echo_ignore_broadcasts" variable with the following command: $ sudo sysctl net.ipv4.icmp_echo_ignore_broadcasts net.ipv4.icmp_echo_ignore_broadcasts = 1 If "net.ipv4.icmp_echo_ignore_broadcasts" is not set to "1" or is missing, this is a finding.

Discussion

Responding to broadcast (ICMP) echoes facilitates network mapping and provides a vector for amplification attacks. Ignoring ICMP echo requests (pings) sent to broadcast or multicast addresses makes the system slightly more difficult to enumerate on the network. Satisfies: SRG-OS-000420-GPOS-00186, SRG-OS-000142-GPOS-00080

Related controls

CCI-001104, CCI-002385

Fix

Configure RHEL 10 to ignore Internet Protocol version 4 (IPv4) ICMP echoes sent to a broadcast address. Create a configuration file if it does not already exist: $ sudo vi /etc/sysctl.d/ipv4_icmp_echo_ignore_broadcasts.conf Add the following line to the file: net.ipv4.icmp_echo_ignore_broadcasts = 1 Reload settings from all system configuration files with the following command: $ sudo sysctl --system