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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-75577	UBTU-16-010810	SV-90257r3_rule		Medium

Description
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.

STIG	Date
Canonical Ubuntu 16.04 Security Technical Implementation Guide	2019-12-23

Details

Check Text ( C-75281r2_chk )
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.

Check Text ( C-75281r2_chk )

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 (F-82205r1_fix)
Configure the "/etc/fstab" to use the "nosuid" option on file systems that are associated with removable media.