SV-271873r1092331: OL 9 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address. | Oracle Linux 9 STIG SCAP Benchmark

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Assessment Title

Rule Text

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

Description

Discussion Text

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.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000366

References

DPMS Target Oracle Linux 9 DISA DPMS Target Oracle Linux 9 5680

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

#!/bin/bash
# Reconstructed from oval:mil.disa.stig.ol9os:def:271873
# OL 9 must not respond to Internet Control Message Protocol (ICMP) echoes sent to a broadcast address.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# net.ipv4.icmp_echo_ignore_broadcasts is set to 1 in kernel
# sysctl_object (sysctl_test)
test_1() {
  [ "$(cat /proc/sys/net/ipv4/icmp_echo_ignore_broadcasts)" -eq 1 ]
}

if test_1; then
  echo "PASS"
else
  echo "FAIL"
fi

Assessment Script Powered by AISandbox-executed

A standalone Shell script to assess this control automatically. Review before running it in your environment.

Syntax-checked and actually executed in an isolated sandbox (not the real system this checks) — confirmed to run without errors.

#!/bin/sh
# OVAL Definition: oval:mil.disa.stig.ol9os:def:271873

if [ ! -f "/etc/sysctl.d/99-default.conf" ]; then
    echo "PASS"
    exit 0
fi

if grep -q "^net.ipv4.icmp_echo_ignore_broadcasts = 1$" /etc/sysctl.d/99-default.conf; then
    echo "PASS"
    exit 0
fi

echo "FAIL"
exit 1

Remediation

Configure OL 9 to not respond to IPv4 ICMP echoes sent to a broadcast address.

Add or edit the following line in a single system configuration file in the "/etc/sysctl.d/" directory:

net.ipv4.icmp_echo_ignore_broadcasts = 1

Load settings from all system configuration files with the following command:

$ sudo sysctl --system