Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
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Date: Fri, 6 Sep 2019 12:44:30 +0200
From: Heiko Schlittermann <hs@...littermann.de>
To: oss-security <oss-security@...ts.openwall.com>,
	Exim Users <exim-users@...m.org>,
	Exim Announce <exim-announce@...m.org>
Subject: Re: CVE-2019-15846: Exim - local or remote attacker can execute
 programs with root privileges.

Heiko Schlittermann <hs@...rc.schlittermann.de> (Fr 06 Sep 2019 12:20:39 CEST):
> Mitigation
> ==========
>
> Do not offer TLS for incomming connections (tls_advertise_hosts).
> This mitigation is *not* recommended!

This should block the most popular attack vector:

In your MAIL ACL:

    deny    condition = ${if eq{\\}{${substr{-1}{1}{$tls_in_sni}}}}
            message = sorry


    Best regards from Dresden/Germany
    Viele Grüße aus Dresden
    Heiko Schlittermann
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