The root account must be the only account having unrestricted access to the system.

From Canonical Ubuntu 16.04 Security Technical Implementation Guide

Associated with: CCI-000366

SV-90229r1_rule The root account must be the only account having unrestricted access to the system.

Vulnerability discussion

If an account other than root also has a User Identifier (UID) of "0", it has root authority, giving that account unrestricted access to the entire Ubuntu operating system. Multiple accounts with a UID of "0" afford an opportunity for potential intruders to guess a password for a privileged account.

Check content

Check the Ubuntu operating system for duplicate User ID (UID) "0" assignments with the following command: # awk -F: '$3 == 0 {print $1}' /etc/passwd root If any accounts other than root have a UID of "0", this is a finding.

Fix text

Change the User ID (UID) of any account on the system, other than root, that has a UID of "0". If the account is associated with system commands or applications, the UID should be changed to one greater than "0" but less than "1000". Otherwise, assign a UID of greater than "1000" that has not already been assigned.

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