The SMTP service must not have the Verify (VRFY) feature active.

From Red Hat Enterprise Linux 5 Security Technical Implementation Guide

Part of GEN004680

Associated with IA controls: ECSC-1

Associated with: CCI-000366

SV-37511r1_rule The SMTP service must not have the Verify (VRFY) feature active.

Vulnerability discussion

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

Check content

Fix text

Add the "novrfy" flag to your sendmail in /etc/mail/sendmail.cf. Procedure: Edit the definition of "confPRIVACY_FLAGS" in /etc/mail/sendmail.mc to include "novrfy". Rebuild the sendmail.cf file with: # make -C /etc/mail Restart the sendmail service. # service sendmail restart

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