SV-237621r991589: The SUSE operating system must prevent Internet Protocol version 6 (IPv6) Internet Control Message Protocol (ICMP) redirect messages from being accepted. | SUSE Linux Enterprise Server 12 STIG SCAP Benchmark

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Assessment Title

Rule Text

The SUSE operating system must prevent Internet Protocol version 6 (IPv6) Internet Control Message Protocol (ICMP) redirect messages from being accepted.

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 modify the host's route table and are unauthenticated. An illicit ICMP redirect message could result in a man-in-the-middle attack.

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 12 DISA DPMS Target SUSE Linux Enterprise Server 12 4033

Checks

DISA STIG (Manual Reference)

Verify the SUSE operating system does not accept IPv6 source-routed packets by default.
Verify the SUSE operating system does not accept IPv6 ICMP redirect messages.

Check the value of the IPv6 accept_redirects variable with the following command:

> sudo sysctl net.ipv6.conf.all.accept_redirects
net.ipv6.conf.all.accept_redirects =0

If the network parameter "ipv6.conf.all.accept_redirects" is not equal to "0" or nothing is returned, this is a finding.

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.sles12os:def:237621
# The SUSE operating system must prevent Internet Protocol version 6 (IPv6) Internet Control Message Protocol (ICMP) redirect messages from being accepted.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# net.ipv6.conf.all.accept_redirects setting in kernel is 0
# sysctl_object (sysctl_test)
test_1() {
  [ "$(cat /proc/sys/net/ipv6/conf/all/accept_redirects)" -eq 0 ]
}

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

Remediation

Configure the SUSE operating system to not accept IPv6 ICMP redirect messages by running the following command as an administrator:

> sudo sysctl -w net.ipv6.conf.all.accept_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.ipv6.conf.all.accept_redirects=0" >> /etc/sysctl.d/99-stig.conf'

> sudo sysctl --system