cis-ubuntu2004-v300-3-2-2

3.2.2 Ensure tipc kernel module is not available (Automated)

Profile

• Level 2 - Server
• Level 2 - Workstation

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 kernel module not be loaded, disabling the service to reduce the potential attack surface.

Impact

None expected if the TIPC protocol is not in use.

Audit Procedure

Command Line

Verify the tipc kernel module is not available on the system or has been disabled. This can be verified by performing the following or by running the audit script included below.

Run the following script to determine if the tipc kernel module is available on the system:

#!/usr/bin/env bash

{
  l_mod_name="tipc" l_mod_type="net"
  while IFS= read -r l_mod_path; do
      if [ -d "$l_mod_path/${l_mod_name//\-/\/}" ] && [ -n "$(ls -A "$l_mod_path/${l_mod_name//\-/\/}")" ]; then
          printf '%s\n' "$l_mod_name exists in $l_mod_path"
      fi
  done < <(readlink -f /usr/lib/modules/**/kernel/$l_mod_type || readlink -f
/lib/modules/**/kernel/$l_mod_type)
}

If nothing is returned, the tipc kernel module is not available on the system and no further audit steps are required. Note: Some systems may include the tipc filesystem as part of the kernel opposed to being available as a kernel module. In this case, the above audit will not return anything. This is also considered a passing state.

If anything is returned, verify the tipc kernel module is not loaded and not loadable by performing the following:

Run the following command to verify the tipc kernel module is not loaded:

# lsmod | grep 'tipc'

Nothing should be returned.

Run the following command to verify the tipc kernel module is not loadable:

# modprobe --showconfig | grep -P -- '\b(install|blacklist)\h+tipc\b'

Verify the output includes:

blacklist tipc
 -AND-
install tipc /bin/false
 -OR-
install tipc /bin/true

Expected Result

The tipc kernel module should not be available, or if present, it should be blacklisted and set to install /bin/false or /bin/true, and not currently loaded.

Remediation

Command Line

Run the following to unload and disable the tipc kernel module. This can also be done by running the script included below.

Run the following commands to unload the tipc kernel module:

# modprobe -r tipc 2>/dev/null
# rmmod tipc 2>/dev/null

Perform the following to disable the tipc kernel module: Create a file ending in .conf with install tipc /bin/false in the /etc/modprobe.d/ directory. Example:

# printf '\n%s\n' "install tipc /bin/false" >> tipc.conf

Create a file ending in .conf with blacklist tipc in the /etc/modprobe.d/ directory. Example:

# printf '\n%s\n' "blacklist tipc" >> tipc.conf

Default Value

tipc kernel module is available but not loaded by default.

References

1. NIST SP 800-53 Rev. 5: SI-4, CM-7

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