SV-253123r991589: TOSS must not allow interfaces to perform Internet Control Message Protocol (ICMP) redirects by default. | Tri-Lab Operating System Stack (TOSS) 4 STIG SCAP Benchmark

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Assessment Title

Rule Text

TOSS must not allow interfaces to perform Internet Control Message Protocol (ICMP) redirects 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. There are notable differences between Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6). There is only a directive to disable sending of IPv4 redirected packets. Refer to RFC4294 for an explanation of "IPv6 Node Requirements", which resulted in this difference between IPv4 and IPv6.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000366

References

DPMS Target TOSS 4 DISA DPMS Target TOSS 4 5469

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.toss4os:def:253123
# TOSS must not allow interfaces to perform Internet Control Message Protocol (ICMP) redirects 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 is set to 0 in kernel
# 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 TOSS: net.ipv4.conf.default.send_redirects must be 0

# Check if sysctl is available
if ! command -v sysctl &> /dev/null; then
  echo "PASS"
  exit 0
fi

# Check the current sysctl value
current_value=$(sysctl -n net.ipv4.conf.default.send_redirects 2> /dev/null)

if [ $? -ne 0 ]; then
  echo "PASS"
  exit 0
fi

if [ "$current_value" -eq 0 ]; then
  echo "PASS"
  exit 0
else
  echo "FAIL"
  exit 1
fi

# Check if the value is set in sysctl.d
if ! grep -qF 'net.ipv4.conf.default.send_redirects=0' /etc/sysctl.d/*; then
  echo "FAIL"
  exit 1
fi

Remediation

Configure TOSS to not allow interfaces to perform Internet Protocol version 4 (IPv4) ICMP redirects by default with the following command:

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

If "0" is not the system's default value then add or update the following line in the appropriate file under "/etc/sysctl.d":

net.ipv4.conf.default.send_redirects=0