Run the following script to disable the cramfs module: If the module is available in the running kernel: - Create a file with install cramfs /bin/false in the /etc/modprobe.d/ directory - Create a file with blacklist cramfs in the /etc/modprobe.d/ directory - Unload cramfs from the kernel If available in ANY installed kernel: - Create a file with blacklist cramfs in the /etc/modprobe.d/ directory If the kernel module is not available on the system or pre-compiled into the kernel: - No remediation is necessary #!/usr/bin/env bash { l_mname="cramfs" # set module name l_mtype="fs" # set module type l_mpath="/lib/modules/**/kernel/$l_mtype" l_mpname="$(tr '-' '_' <<< "$l_mname")" l_mndir="$(tr '-' '/' <<< "$l_mname")" module_loadable_fix() { # If the module is currently loadable, add "install {MODULE_NAME} /bin/false" to a file in "/etc/modprobe.d" l_loadable="$(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)' <<< "$l_loadable"; then echo -e " - setting module: \"$l_mname\" to be not loadable" echo -e "install $l_mname /bin/false" >> /etc/modprobe.d/"$l_mpname".conf fi } module_loaded_fix() { # If the module is currently loaded, unload the module if lsmod | grep "$l_mname" > /dev/null 2>&1; then echo -e " - unloading module \"$l_mname\"" modprobe -r "$l_mname" fi } module_deny_fix() { # If the module isn't deny listed, denylist the module if ! modprobe --showconfig | grep -Pq -- "^h*blacklisth+$l_mpnameb"; then echo -e " - deny listing \"$l_mname\"" echo -e "blacklist $l_mname" >> /etc/modprobe.d/"$l_mpname".conf fi } # Check if the module exists on the system for l_mdir in $l_mpath; do if [ -d "$l_mdir/$l_mndir" ] && [ -n "$(ls -A $l_mdir/$l_mndir)" ]; then echo -e " - module: \"$l_mname\" exists in \"$l_mdir\" - checking if disabled..." module_deny_fix if [ "$l_mdir" = "/lib/modules/$(uname -r)/kernel/$l_mtype" ]; then module_loadable_fix module_loaded_fix fi else echo -e " - module: \"$l_mname\" doesn't exist in \"$l_mdir\" " fi done echo -e " - remediation of module: \"$l_mname\" complete " }

Name	Audit Name	Plugin	Category
1.1.1.1 Ensure mounting of cramfs filesystems is disabled	CIS Ubuntu Linux 20.04 LTS Workstation L1 v2.0.1	Unix	CONFIGURATION MANAGEMENT
1.1.1.1 Ensure mounting of cramfs filesystems is disabled	CIS Ubuntu Linux 20.04 LTS Server L1 v2.0.1	Unix	CONFIGURATION MANAGEMENT

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