Title

The SMTP services SMTP greeting must not provide version information. (Cat III impact)

Discussion

The version of the SMTP service can be used by attackers to plan an attack based on vulnerabilities present in the specific version.

Check Content

To check for the version of either sendmail or Postfix being displayed in the greeting: # telnet localhost 25 If a version number is displayed, this is a finding.

Fix Text

Ensure sendmail or Postfix has been configured to mask the version information. Procedure for sendmail: Edit the /etc/mail/sendmail.mc file to mask the veresion number by editing the line with "dnl" as follows: define(`confSMTP_LOGIN_MSG', ` Mail Server Ready ; $b')dnl rebuild the sendmail.cf file. for Postfix: Examine the "smtpd_banner" line of /etc/postfix/main.conf and remove any "$mail_version" entry on it or comment the entire "smtpd_banner" line to use the default value which does not display the version information.

Additional Identifiers

Rule ID: SV-46278r1_rule

Vulnerability ID: V-4384

Group Title: GEN004560

Expert Comments

CCIs tied to check.

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