Vulnerability Discussion

The "nosuid" mount option causes the system not to 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

Verify that file systems containing user home directories are mounted with the "nosuid" option.

Find the file system(s) that contain the user home directories with the following command:

$ sudo awk -F: '($3>=1000)&&($1!="nobody"){print $1,$3,$6}' /etc/passwd

smithj 1001 /home/smithj
robinst 1002 /home/robinst

Check the file systems that are mounted at boot time with the following command:

$ sudo more /etc/fstab

UUID=a411dc99-f2a1-4c87-9e05-184977be8539 /home ext4 rw,relatime,discard,data=ordered,nosuid,nodev,noexec 0 2

If a file system found in "/etc/fstab" refers to the user home directory file system and it does not have the "nosuid" option set, this is a finding.

Fix

Configure "/etc/fstab" to use the "nosuid" option on file systems that contain user home directories for interactive users.