Vulnerability Discussion

The sudoers security policy requires that users authenticate themselves before they can use sudo. When sudoers requires authentication, it validates the invoking user's credentials. If the rootpw, targetpw, or runaspw flags are defined and not disabled, by default the operating system will prompt the invoking user for the "root" user password.
For more information on each of the listed configurations, reference the sudoers(5) manual page.

Check

Verify that the sudoers security policy is configured to use the invoking user's password for privilege escalation.

$ sudo egrep -ir '(rootpw|targetpw|runaspw)' /etc/sudoers /etc/sudoers.d* | grep -v '#'

/etc/sudoers:Defaults !targetpw
/etc/sudoers:Defaults !rootpw
/etc/sudoers:Defaults !runaspw

If conflicting results are returned, this is a finding.
If "Defaults !targetpw" is not defined, this is a finding.
If "Defaults !rootpw" is not defined, this is a finding.
If "Defaults !runaspw" is not defined, this is a finding.

Fix

Define the following in the Defaults section of the /etc/sudoers file or a configuration file in the /etc/sudoers.d/ directory:
Defaults !targetpw
Defaults !rootpw
Defaults !runaspw