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3.2.2 Ensure tipc kernel module is not available

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Information

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

- 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.

Solution

Run the following script to unload and disable the tipc module:

- IF - the tipc kernel module is available in ANY installed kernel:

 - Create a file ending inconf with install tipc /bin/false in the /etc/modprobe.d/ directory
 - Create a file ending inconf with blacklist tipc in the /etc/modprobe.d/ directory
 - Run modprobe -r tipc 2>/dev/null; rmmod tipc 2>/dev/null to remove tipc from the kernel

- IF - the tipc kernel module is not available on the system, or pre-compiled into the kernel, no remediation is necessary

#!/usr/bin/env bash

{
 a_output2=() a_output3=() l_dl="" l_mod_name="tipc" l_mod_type="net"
 l_mod_path="$(readlink -f /usr/lib/modules/**/kernel/$l_mod_type || readlink -f /lib/modules/**/kernel/$l_mod_type)"
 f_module_fix()
 {
 l_dl="y" a_showconfig=()
 while IFS= read -r l_showconfig; do
 a_showconfig+=("$l_showconfig")
 done < <(modprobe --showconfig | grep -P -- 'b(install|blacklist)h+'"${l_mod_chk_name//-/_}"'b')
 if lsmod | grep "$l_mod_chk_name" &> /dev/null; then
 a_output2+=(" - unloading kernel module: \"$l_mod_name\"")
 modprobe -r "$l_mod_chk_name" 2>/dev/null; rmmod "$l_mod_name" 2>/dev/null
 fi
 if ! grep -Pq -- 'binstallh+'"${l_mod_chk_name//-/_}"'h+(/usr)?/bin/(true|false)b' <<< "${a_showconfig[*]}"; then
 a_output2+=(" - setting kernel module: \"$l_mod_name\" to \"$(readlink -f /bin/false)\"")
 printf '%s
' "install $l_mod_chk_name $(readlink -f /bin/false)" >> /etc/modprobe.d/"$l_mod_name".conf
 fi
 if ! grep -Pq -- 'bblacklisth+'"${l_mod_chk_name//-/_}"'b' <<< "${a_showconfig[*]}"; then
 a_output2+=(" - denylisting kernel module: \"$l_mod_name\"")
 printf '%s
' "blacklist $l_mod_chk_name" >> /etc/modprobe.d/"$l_mod_name".conf
 fi
 }
 for l_mod_base_directory in $l_mod_path; do # Check if the module exists on the system
 if [ -d "$l_mod_base_directory/${l_mod_name/-//}" ] && [ -n "$(ls -A "$l_mod_base_directory/${l_mod_name/-//}")" ]; then
 a_output3+=(" - \"$l_mod_base_directory\"")
 l_mod_chk_name="$l_mod_name"
 [[ "$l_mod_name" =~ overlay ]] && l_mod_chk_name="${l_mod_name::-2}"
 [ "$l_dl" != "y" ] && f_module_fix
 else
 printf '%s
' " - kernel module: \"$l_mod_name\" doesn't exist in \"$l_mod_base_directory\""
 fi
 done
 [ "${#a_output3[@]}" -gt 0 ] && printf '%s
' "" " -- INFO --" " - module: \"$l_mod_name\" exists in:" "${a_output3[@]}"
 [ "${#a_output2[@]}" -gt 0 ] && printf '%s
' "" "${a_output2[@]}" || printf '%s
' "" " - No changes needed"
 printf '%s
' "" " - remediation of kernel module: \"$l_mod_name\" complete" ""
}

See Also

https://workbench.cisecurity.org/benchmarks/20333

Item Details

References: CSCv7|9.2

Plugin: Unix

Control ID: f96774649f5ef1cbfff0b6628e7ad0f5f4a33ea4fcbb57670afda4c4ad7c1ef1