All accounts must be assigned unique User Identification Numbers (UIDs).

From Oracle Linux 5 Security Technical Implementation Guide

Associated with: CCI-000764

SV-63255r1_rule All accounts must be assigned unique User Identification Numbers (UIDs).

Vulnerability discussion

Accounts sharing a UID have full access to each others' files. This has the same effect as sharing a login. There is no way to assure identification, authentication, and accountability because the system sees them as the same user. If the duplicate UID is 0, this gives potential intruders another privileged account to attack.

Check content

Perform the following to ensure there are no duplicate UIDs: # cut -d: -f3 /etc/passwd | uniq -d If any duplicate UIDs are found, this is a finding.

Fix text

Edit user accounts to provide unique UIDs for each account.

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