The SMTP service must not have the EXPN feature active.

From HP-UX 11.23 Security Technical Implementation Guide

Associated with IA controls: ECSC-1

Associated with: CCI-000366

SV-35076r1_rule The SMTP service must not have the EXPN feature active.

Vulnerability discussion

The SMTP EXPN function allows an attacker to determine if an account exists on a system, providing significant assistance to a brute force attack on user accounts. EXPN may also provide additional information concerning users on the system, such as the full names of account owners.

Check content

Fix text

Edit the /etc/mail/sendmail.cf file and add or edit the following line: O PrivacyOptions=goaway Then restart the Sendmail service.

Pro Tips

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