starttls_injection_policy

March 26, 2020 Contributors

Name

starttls_injection_policy — protect against SMTP injections prior to TLS

Synopsis

starttls_injection_policy = "reject"

Description

**Configuration Change. ** This feature is available as of version 3.3.

This option deals with the security issue described by CVE-2011-0411—namely that SMTP commands can be injected before the MTA switches to TLS. Consequently, a "man in the middle" could inject SMTP commands that are not protected by TLS.

This option has three possible values: allow, reject, ignore. The default value for this option is reject. When set to reject, if any commands are present in the buffer immediately after a STARTTLS command, then the STARTTLS is rejected and the connection is dropped. This event will be logged in the rejectlog.

If the value is ignore, then any commands after STARTTLS are ignored and commands after the successful TLS negotiation will be interpreted. When set to allow, the ESMTP listener will process commands after STARTTLS and before successful SSL negotiation. allow was the only supported behavior prior to Momentum 3.3.

Scope

This option is valid in the ESMTP_Listener, listen, pathway, pathway_group and peer scopes.