The alias file must be owned by root.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-831	GEN004360	SV-37472r2_rule	ECLP-1	Medium

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

STIG	Date
Red Hat Enterprise Linux 5 Security Technical Implementation Guide	2015-06-12

Details

Check Text ( C-36137r2_chk )
If the "sendmail" and "postfix" packages are not installed, this is not applicable. Check the ownership of the alias files. Procedure: for sendmail: # ls -lL /etc/aliases # ls -lL /etc/aliases.db If all the files are not owned by root, 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 # ls -lL If all the files are not owned by root, this is a finding.

Check Text ( C-36137r2_chk )

If the "sendmail" and "postfix" packages are not installed, this is not applicable.

Check the ownership of the alias files.

Procedure:
for sendmail:
# ls -lL /etc/aliases
# ls -lL /etc/aliases.db
If all the files are not owned by root, 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
# ls -lL
If all the files are not owned by root, this is a finding.

Fix Text (F-31384r1_fix)
Change the owner of the /etc/aliases file to root. Procedure: for sendmail: # chown root /etc/aliases # chown root /etc/aliases.db for postfix # chown root /etc/postfix/aliases # chown root /etc/postfix/aliases.db