Detections
Analytics
ALMA-09-019050 - AlmaLinux OS 9 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.
Information
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.
Solution
Configure AlmaLinux OS 9 to use reverse path filtering on all IP interfaces.Create a numbered *.conf file in /etc/sysctl.d/ with the following content:
net.ipv4.icmp_echo_ignore_broadcasts = 1
The system configuration files need to be reloaded for the changes to take effect. To reload the contents of the files, run the following command:
$ sysctl -system
See Also
https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_CL_AlmaLinux_OS_9_V1R6_STIG.zip
Item Details
Audit Name: DISA Cloud Linux AlmaLinux OS 9 STIG v1r6
Category: CONFIGURATION MANAGEMENT
References: 800-53|CM-6b., CAT|II, CCI|CCI-000366, Rule-ID|SV-269248r1050130_rule, STIG-ID|ALMA-09-019050, Vuln-ID|V-269248
Plugin: Unix
Control ID: 997a6ef2e83ddff5a878683e54a616d14c3a7931107e3fe4ba6ded1fddff42ee