1.1.1.3 Ensure mounting of udf filesystems is disabled

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Information

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.

Solution

Run the following script to disable the udf filesystem:

#!/usr/bin/env bash

{
l_mname='udf' # set module name
if ! modprobe -n -v '$l_mname' | grep -P -- '^h*install /bin/(true|false)'; then
echo -e ' - setting module: '$l_mname' to be not loadable'
echo -e 'install $l_mname /bin/false' >> /etc/modprobe.d/'$l_mname'.conf
fi
if lsmod | grep '$l_mname' > /dev/null 2>&1; then
echo -e ' - unloading module '$l_mname''
modprobe -r '$l_mname'
fi
if ! grep -Pq -- '^h*blacklisth+$l_mnameb' /etc/modprobe.d/*; then
echo -e ' - deny listing '$l_mname''
echo -e 'blacklist $l_mname' >> /etc/modprobe.d/'$l_mname'.conf
fi
}

See Also

https://workbench.cisecurity.org/files/4068