The aliases file must be group-owned by root, sys, bin, or system.

From Oracle Linux 5 Security Technical Implementation Guide

Associated with: CCI-000225

SV-63613r1_rule The aliases file must be group-owned by root, sys, bin, or system.

Vulnerability discussion

If the alias file is not group-owned by root or a system group, an unauthorized user may modify the file adding aliases to run malicious code or redirect e-mail.

Check content

If the "sendmail" and "postfix" packages are not installed, this is not applicable. Check the group ownership of the alias files. Procedure: for sendmail: # ls -lL /etc/aliases If the files are not group-owned by root, this is a finding. # ls -lL /etc/aliases.db If the file is not group-owned by the same system group as sendmail, which is smmsp by default, this is a finding. for postfix: Verify the location of the alias file. # postconf alias maps This will return the location of the "aliases" file, by default "/etc/postfix/aliases" # ls -lL If the files are not group-owned by root, this is a finding. # ls -lL If the file is not group-owned by root, this is a finding.

Fix text

Change the group-owner of the /etc/aliases file. Procedure: for sendmail: # chgrp root /etc/aliases # chgrp smmsp /etc/aliases.db The aliases.db file must be owned by the same system group as sendmail, which is smmsp by default. for postfix # chgrp root /etc/postfix/aliases # chgrp root /etc/postfix/aliases.db

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