AlmaLinux OS 9 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-269248 | ALMA-09-019050 | SV-269248r1050130_rule | CCI-000366 | medium |
| Description | ||||
| 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. | ||||
| STIG | Date | |||
| CloudLinux AlmaLinux OS 9 Security Technical Implementation Guide | 2025-05-22 | |||
Related Frameworks
4 paths across 3 frameworks
Related Frameworks
NIST 800-531 mapping
CM-6
1.00
- DISA · 1 · disa_xccdf · related
- DISA · 2025-01-23 · disa_cci_list · equivalent
NIST 800-1712 mappings
3.4.1
1.00
- DISA · 1 · disa_xccdf · related
- DISA · 2025-01-23 · disa_cci_list · equivalent
- NIST · Rev 2 (Feb 2020, errata Jan 2021) · nist_800_171_app_d · equivalent
3.4.2
1.00
- DISA · 1 · disa_xccdf · related
- DISA · 2025-01-23 · disa_cci_list · equivalent
- NIST · Rev 2 (Feb 2020, errata Jan 2021) · nist_800_171_app_d · equivalent
CCI1 mapping
CCI-000366
1.00
- DISA · 1 · disa_xccdf · related
Details
Check Text (C-269248r1050130_chk)
Verify AlmaLinux OS 9 does not respond to ICMP echoes sent to a broadcast address with the following command:
$ sysctl net.ipv4.icmp_echo_ignore_broadcasts
net.ipv4.icmp_echo_ignore_broadcasts = 1
If the returned line does not have a value of "1", this is a finding.
Fix Text (F-73180r1049377_fix)
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