Detections
Analytics
3.2.3 Ensure rds kernel module is not available
Information
The Reliable Datagram Sockets (RDS) protocol is a transport layer protocol designed to provide low-latency, high-bandwidth communications between cluster nodes. It was developed by the Oracle Corporation.- 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 rds module:- IF - the rds kernel module is available in ANY installed kernel:
- Create a file ending inconf with install rds /bin/false in the /etc/modprobe.d/ directory
- Create a file ending inconf with blacklist rds in the /etc/modprobe.d/ directory
- Run modprobe -r rds 2>/dev/null; rmmod rds 2>/dev/null to remove rds from the kernel
- IF - the rds kernel module is not available on the system, or pre-compiled into the kernel, no remediation is necessary
#!/usr/bin/env bash
{
unset a_output2; l_output3="" l_dl="" # unset arrays and clear variables
l_mod_name="rds" # set module name
l_mod_type="net" # set module type
l_mod_path="$(readlink -f /lib/modules/**/kernel/$l_mod_type | sort -u)"
f_module_fix()
{
l_dl="y" # Set to ignore duplicate checks
a_showconfig=() # Create array with modprobe output
while IFS= read -r l_showconfig; do
a_showconfig+=("$l_showconfig")
done < <(modprobe --showconfig | grep -P -- 'b(install|blacklist)h+'"${l_mod_name//-/_}"'b')
if lsmod | grep "$l_mod_name" &> /dev/null; then # Check if the module is currently loaded
a_output2+=(" - unloading kernel module: \"$l_mod_name\"")
modprobe -r "$l_mod_name" 2>/dev/null; rmmod "$l_mod_name" 2>/dev/null
fi
if ! grep -Pq -- 'binstallh+'"${l_mod_name//-/_}"'h+/bin/(true|false)b' <<< "${a_showconfig[*]}"; then
a_output2+=(" - setting kernel module: \"$l_mod_name\" to \"/bin/false\"")
printf '%s
' "install $l_mod_name /bin/false" >> /etc/modprobe.d/"$l_mod_name".conf
fi
if ! grep -Pq -- 'bblacklisth+'"${l_mod_name//-/_}"'b' <<< "${a_showconfig[*]}"; then
a_output2+=(" - denylisting kernel module: \"$l_mod_name\"")
printf '%s
' "blacklist $l_mod_name" >> /etc/modprobe.d/"$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
l_output3="$l_output3
- \"$l_mod_base_directory\""
[[ "$l_mod_name" =~ overlay ]] && l_mod_name="${l_mod_name::-2}"
[ "$l_dl" != "y" ] && f_module_fix
else
echo -e " - kernel module: \"$l_mod_name\" doesn't exist in \"$l_mod_base_directory\""
fi
done
[ -n "$l_output3" ] && echo -e "
-- INFO --
- module: \"$l_mod_name\" exists in:$l_output3"
[ "${#a_output2[@]}" -gt 0 ] && printf '%s
' "${a_output2[@]}"
echo -e "
- remediation of kernel module: \"$l_mod_name\" complete
"
}
See Also
Item Details
Audit Name: CIS AlmaLinux OS 9 v2.0.0 L2 Server
Category: CONFIGURATION MANAGEMENT
References: 800-53|CM-6, 800-53|CM-7, CSCv7|9.2
Plugin: Unix
Control ID: 6e53dcc67a9e3ca33a0abd18c0bfaa6a174afb616e1fc14309bca8b59ba1212b