1.1.1.3 Ensure mounting of udf filesystems is disabled

Profile Applicability:  Level 2 - Server  Level 2 - Workstation Description: The udf filesystem type is the universal disk format used to implement ISO/IEC 13346 and ECMA-167 specifications. This is an open vendor filesystem type for data storage on a broad range of media. This filesystem type is necessary to support writing DVDs and newer optical disc formats. Rationale: Removing support for unneeded filesystem types reduces the local attack surface of the system. If this filesystem type is not needed, disable it. Impact: Microsoft Azure requires the usage of udf. udf should not be disabled on systems run on Microsoft Azure.

Audit: Run the following script to verify udf is disabled:

#!/usr/bin/env bash
{
l_output="" l_output2=""
l_mname="udf" # set module name
# Check how module will be loaded
l_loadable="$(modprobe -n -v "$l_mname")"
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:
\"$l_loadable\""
fi
# Check is the module currently loaded
if ! lsmod | grep "$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
# Check if the module is deny listed
if grep -Pq -- "^\h*blacklist\h+$l_mname\b" /etc/modprobe.d/*; then
l_output="$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: \"$l_mname\" is not deny listed"
fi
# Report results. If no failures output in l_output2, we pass
if [ -z "$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
}

sandevistan-server-hardening / CIS_Ubuntu_22.04_LTS_Benchmark_v1.0.0

1.1.1.3 Ensure mounting of udf filesystems is disabled #3