Detections
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1.145 ALMA-09-019050

Information

AlmaLinux OS 9 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.

GROUP ID: V-269248
RULE ID: SV-269248r1050130

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://workbench.cisecurity.org/benchmarks/27039

Item Details

Category: CONFIGURATION MANAGEMENT

References: 800-53|CM-6b., CCI|CCI-000366, Rule-ID|SV-269248r1050130_rule, STIG-ID|ALMA-09-019050, Vuln-ID|V-269248

Plugin: Unix

Control ID: 503cef36dd9e8ca73d739f64ab64c8026c784dececf5d4461498f95d85a5088b