Cis Ubuntu1604 V200 3 1 2

CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 3.1.2

Description

Wireless networking is used when wired networks are unavailable. Debian contains a wireless tool kit to allow system administrators to configure and use wireless networks.

Rationale

If wireless is not to be used, wireless devices can be disabled to reduce the potential attack surface.

Impact

Many if not all laptop workstations and some desktop workstations will connect via wireless requiring these interfaces be enabled.

Audit Procedure

Command Line

Run the following script to verify no wireless interfaces are active on the system:

#!/bin/bash
if command -v nmcli >/dev/null 2>&1 ; then
  nmcli radio all | grep -Eq '\s*\S+\s+disabled\s+\S+\s+disabled\b' && echo "Wireless is not enabled" || nmcli radio all
elif [ -n "$(find /sys/class/net/*/ -type d -name wireless)" ]; then
  t=0
  drivers=$(for driverdir in $(find /sys/class/net/*/ -type d -name wireless | xargs -0 dirname); do basename "$(readlink -f "$driverdir"/device/driver)";done | sort -u)
  for dm in $drivers; do
    if grep -Eq "^\s*install\s+$dm\s+/bin/(true|false)" /etc/modprobe.d/*.conf; then
      /bin/true
    else
      echo "$dm is not disabled"
      t=1
    fi
  done
  [[ $t -eq 0 ]] && echo "Wireless is not enabled"
else
  echo "Wireless is not enabled"
fi

Expected Result

Wireless is not enabled

Remediation

Command Line

Run the following script to disable any wireless interfaces:

#!/bin/bash
if command -v nmcli >/dev/null 2>&1 ; then
  nmcli radio all off
else
  if [ -n "$(find /sys/class/net/*/ -type d -name wireless)" ]; then
    drivers=$(for driverdir in $(find /sys/class/net/*/ -type d -name wireless | xargs -0 dirname); do basename "$(readlink -f "$driverdir"/device/driver)";done | sort -u)
    for dm in $drivers; do
      echo "install $dm /bin/true" >> /etc/modprobe.d/disable_wireless.conf
    done
  fi
fi

Default Value

Wireless interfaces may be enabled by default.

References

1. CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0

CIS Controls

Version 7

15.4 Disable Wireless Access on Devices if Not Required - Disable wireless access on devices that do not have a business purpose for wireless access.

15.5 Limit Wireless Access on Client Devices - Configure wireless access on client machines that do have an essential wireless business purpose, to allow access only to authorized wireless networks and to restrict access to other wireless networks.

Profile Applicability

• Level 1 - Server
• Level 2 - Workstation

Assessment Status

Automated