Webmail hole?

Hello,

I'm using SM 1.4.6 on a SLES 10 platform with Apache/2.2.8 (Unix) mod_ssl/2.2.8 OpenSSL/0.9.8a PHP/5.2.9 (HOSTNAME: annina.mydomain.tld [xxx.yyy.zzz.www]) installed.

On my mail gateway I noted some queued messages that has headers like this:

Received: from localhost (localhost [127.0.0.1])
        by av8.mydomain.tld (Postfix) with ESMTP id 77DB615B679;
        Wed,  3 Jun 2009 01:32:48 +0200 (CEST)
X-Virus-Scanned: amavisd-new at stt.vir
Received: from av8.mydomain.tld ([127.0.0.1])
        by localhost (av8.stt.vir [127.0.0.1]) (amavisd-new, port 10026)
        with ESMTP id fH8gW7H4kqOH; Wed,  3 Jun 2009 01:32:48 +0200 (CEST)
Received: from webmail.mydomain.tld (annina.mydomain.tld [xxx.yyy.zzz.www])
        by av8.mydomain.tld (Postfix) with ESMTP id EDC0115B678;
        Wed,  3 Jun 2009 01:32:47 +0200 (CEST)
Received: from 80.237.152.53 (proxying for unknown)
        (SquirrelMail authenticated user <imap_user>)
        by webmail.mydomain.tld with HTTP;
        Wed, 3 Jun 2009 01:33:39 +0200 (CEST)
Message-ID: <49689.80.237.152.53.1243985619.squirrel@...>

Could I know how it is possible to use SM as a source of SPAM and how to prevent that this happens?

Is it only a matter of weakness of credential of IMAP user <imap_user> or the authentication is workarounded at all?

Thanks in advance for the exhaustive explanation of this attack.

rocsca


Rocco Scappatura
Assurance & Delivery Sistemi Verona
Infracom Network Application S.p.A.
Attività di direzione e coordinamento Infragruppo S.p.A.
Gruppo Infracom
Via Meucci, 14
37135 Verona
Italia
Telefono        +39 045 9695153
Telefax         +39 045 9690370
Cellulare       +39 335 7276547
Rocco.Scappatura@...
www.infracomna.it
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