TOSS 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-253128 | TOSS-04-040870 | SV-253128r991589_rule | CCI-000366 | medium |
| Description | ||||
| Responding to broadcast ICMP echoes facilitates network mapping and provides a vector for amplification attacks. There are notable differences between Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6). IPv6 does not implement the same method of broadcast as IPv4. Instead, IPv6 uses multicast addressing to the all-hosts multicast group. Refer to RFC4294 for an explanation of "IPv6 Node Requirements", which resulted in this difference between IPv4 and IPv6. | ||||
| STIG | Date | |||
| Tri-Lab Operating System Stack (TOSS) 4 Security Technical Implementation Guide | 2025-05-08 | |||
Details
Check Text (C-253128r991589_chk)
Verify TOSS does not respond to ICMP echoes sent to a broadcast address.
Note: If IPv4 is disabled on the system, this requirement is Not Applicable.
Check the value of the "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 the returned line does not have a value of "1", a line is not returned, or the retuned line is commented out, this is a finding.
Fix Text (F-56531r825055_fix)
Configure TOSS to not respond to IPv4 ICMP echoes sent to a broadcast address with the following command:
$ sudo sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=1
If "1" is not the system's default value then add or update the following line in the appropriate file under "/etc/sysctl.d":
net.ipv4.icmp_echo_ignore_broadcasts=1