Cis Ubuntu1804 V220 3 2 2

CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0 - Control 3.2.2

Description

The Transparent Inter-Process Communication (TIPC) protocol is designed to provide communication between cluster nodes.

Rationale

If the protocol is not being used, it is recommended that the kernel module drivers not be installed to reduce the potential attack surface.

Impact

None.

Audit Procedure

Command Line

Run the following script to verify the tipc module is not available:

#!/usr/bin/bash
{
  l_mname="tipc"
  l_mtype="net"
  l_output="" l_output2="" l_output3=""

  l_loadable="$(modprobe -n -v "$l_mname")"
  [ "$(wc -l <<< "$l_loadable")" -gt "1" ] && l_loadable="$(grep -P -- "(^\h*install|\b$l_mname)\b" <<< "$l_loadable")"
  if grep -Pq -- '^\h*install \/bin\/(true|false)' <<< "$l_loadable"; then
    l_output="$l_output\n - module: \"$l_mname\" is not loadable: \"$l_loadable\""
  else
    l_output2="$l_output2\n - module: \"$l_mname\" is loadable: \"$l_loadable\""
  fi

  if ! lsmod | grep "$l_mname" > /dev/null 2>&1; then
    l_output="$l_output\n - module: \"$l_mname\" is not loaded"
  else
    l_output2="$l_output2\n - module: \"$l_mname\" is loaded"
  fi

  if modprobe --showconfig | grep -Pq -- "^\h*blacklist\h+$l_mname\b"; then
    l_output="$l_output\n - module: \"$l_mname\" is deny listed in: \"$(grep -Pl -- "^\h*blacklist\h+$l_mname\b" /etc/modprobe.d/*)\""
  else
    l_output2="$l_output2\n - module: \"$l_mname\" is not deny listed"
  fi

  if [ -z "$l_output2" ]; then
    echo -e "\n- Audit Result:\n ** PASS **\n$l_output\n"
  else
    echo -e "\n- Audit Result:\n ** FAIL **\n - Reason(s) for audit failure:\n$l_output2\n"
    [ -n "$l_output" ] && echo -e "\n- Correctly set:\n$l_output\n"
  fi
}

Expected Result

- Audit Result:
 ** PASS **
 - module: "tipc" is not loadable: "install /bin/true"
 - module: "tipc" is not loaded
 - module: "tipc" is deny listed in: "/etc/modprobe.d/<filename>.conf"

Remediation

Command Line

Run the following script to disable the tipc module:

#!/usr/bin/bash
{
  l_mname="tipc"

  if ! modprobe -n -v "$l_mname" | grep -P -- '^\h*install \/bin\/(true|false)'; then
    echo -e " - setting module: \"$l_mname\" to be not loadable"
    echo -e "install $l_mname /bin/false" >> /etc/modprobe.d/"$l_mname".conf
  fi

  if lsmod | grep "$l_mname" > /dev/null 2>&1; then
    echo -e " - unloading module \"$l_mname\""
    modprobe -r "$l_mname"
  fi

  if ! modprobe --showconfig | grep -Pq -- "^\h*blacklist\h+$l_mname\b"; then
    echo -e " - deny listing \"$l_mname\""
    echo -e "blacklist $l_mname" >> /etc/modprobe.d/"$l_mname".conf
  fi
}

Default Value

tipc module is available by default.

References

1. NIST SP 800-53 Rev. 5: CM-7
2. CIS Ubuntu Linux 18.04 LTS Benchmark v2.2.0

CIS Controls

Version 8

4.8 Uninstall or Disable Unnecessary Services on Enterprise Assets and Software - Uninstall or disable unnecessary services on enterprise assets and software.

Version 7

9.2 Ensure Only Approved Ports, Protocols and Services Are Running - Ensure that only network ports, protocols, and services listening on a system with validated business needs, are running on each system.

Profile Applicability

• Level 2 - Server
• Level 2 - Workstation

Assessment Status

Automated