File systems that are used with removable media must be mounted to prevent files with the setuid and setguid bit set from being executed.

From Canonical Ubuntu 16.04 Security Technical Implementation Guide

Associated with: CCI-000366

SV-90257r3_rule File systems that are used with removable media must be mounted to prevent files with the setuid and setguid bit set from being executed.

Vulnerability discussion

The "nosuid" mount option causes the system to not execute "setuid" and "setgid" files with owner privileges. This option must be used for mounting any file system not containing approved "setuid" and "setguid" files. Executing files from untrusted file systems increases the opportunity for unprivileged users to attain unauthorized administrative access.

Check content

Verify file systems that are used for removable media are mounted with the "nosuid" option. Check the file systems that are mounted at boot time with the following command: # more /etc/fstab UUID=2bc871e4-e2a3-4f29-9ece-3be60c835222 /mnt/usbflash vfat noauto,owner,ro,nosuid 0 0 If a file system found in "/etc/fstab" refers to removable media and it does not have the "nosuid" option set, this is a finding.

Fix text

Configure the "/etc/fstab" to use the "nosuid" option on file systems that are associated with removable media.

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