The SMTP service HELP command must not be enabled.

From Oracle Linux 5 Security Technical Implementation Guide

Part of GEN004540

Associated with: CCI-000366

SV-63759r2_rule The SMTP service HELP command must not be enabled.

Vulnerability discussion

The HELP command should be disabled to mask version information. The version of the SMTP service software could be used by attackers to target vulnerabilities present in specific software versions.

Check content

Check if Help is disabled. This rule is for "sendmail" only and not applicable to "Postfix". Procedure: # telnet localhost 25 > help If the help command returns any sendmail version information, this is a finding. If sendmail is not installed, this check is not applicable.

Fix text

To disable the SMTP HELP command, clear the Sendmail help file. # echo > /etc/mail/helpfile

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