Title

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

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

Verify the consistency of the assigned home directories in the authentication database. For Trusted Mode: # authck -av For SMSE: # pwck If a non-unique UID is found in the password file, this is a finding.

Fix Text

Determine if the duplicate UIDs are associated with the same or a different account name. # cat /etc/passwd | grep <non-uniqueUID> or, for multiple non-unique UIDs: # cat /etc/passwd | egrep “<non-uniqueUID1>|<non-uniqueUID2>|,non-uniqueUIDn>“ If the account names are unique, the UIDs must also be modified to be unique. If the account names are the same, disable/remove one of the two (or more) password file entries via the SAM/SMH interface. .

Additional Identifiers

Rule ID: SV-38443r2_rule

Vulnerability ID: V-762

Group Title: GEN000320

Expert Comments

CCIs tied to check.

Controls tied to check. These are derived from the CCIs shown above.