SV-235022r991589: The SUSE operating system must not allow interfaces to send Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages by default. | SUSE Linux Enterprise Server 15 STIG SCAP Benchmark

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Assessment Title

Rule Text

The SUSE operating system must not allow interfaces to send Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages by default.

Description

Discussion Text

ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages contain information from the system's route table, possibly revealing portions of the network topology.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000366

References

DPMS Target SUSE Linux Enterprise Server 15 DISA DPMS Target SUSE Linux Enterprise Server 15 5274

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.sles15:def:232
# The SUSE operating system must not allow interfaces to send Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirect messages by default.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# net.ipv4.conf.default.send_redirects setting in kernel is 0
# sysctl_object (sysctl_test)
test_1() {
  [ "$(cat /proc/sys/net/ipv4/conf/default/send_redirects)" -eq 0 ]
}

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
# DISA STIG / SCAP compliance check for SUSE OS not allowing IPv4 ICMP redirects by default
if [ ! -x /usr/sbin/sysctl ]; then echo "FAIL"; exit 1; fi
if [ $(sysctl -n net.ipv4.conf.default.send_redirects 2>/dev/null) -eq 0 ]; then echo "PASS"; exit 0; fi
if [ ! -f /etc/sysctl.d/99-stig.conf ]; then echo "PASS"; exit 0; fi
if ! grep -q "^net.ipv4.conf.default.send_redirects=0$" /etc/sysctl.d/99-stig.conf; then echo "FAIL"; exit 1; fi
echo "PASS"; exit 0

Remediation

Configure the SUSE operating system to not allow interfaces to perform IPv4 ICMP redirects by default by running the following command as an administrator:

> sudo sysctl -w net.ipv4.conf.default.send_redirects=0

If "0" is not the system's default value, add or update the following line in "/etc/sysctl.d/99-stig.conf":

> sudo sh -c 'echo "net.ipv4.conf.default.send_redirects=0" >> /etc/sysctl.d/99-stig.conf'

> sudo sysctl --system