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6.2.6 Ensure no duplicate user names exist

Information

Although the adduser or pw program will not let you create a duplicate user name, it is possible for an administrator to manually edit the /etc/passwd file and change the username.

If a user is assigned a duplicate user name, it will create and have access to files with the first UID for that username in /etc/passwd . For example, if "test4" has a UID of 1000 and a subsequent "test4" entry has a UID of 2000, logging in as "test4" will use UID 1000. Effectively, the UID is shared, which is a security problem.

Solution

Establish unique user names for the users based on the audit script's results. As long as the users have unique UIDs, file ownership will automatically reflect the change.

See Also

https://workbench.cisecurity.org/benchmarks/19044

Item Details

Category: CONFIGURATION MANAGEMENT, IDENTIFICATION AND AUTHENTICATION

References: 800-53|CM-1, 800-53|CM-2, 800-53|CM-6, 800-53|CM-7, 800-53|IA-5

Plugin: Unix

Control ID: 899cd4a73e9fd4a1a4caf4f76f868843bb1625ed64d51ff5ad40450cbb3379a4