Transparent hijacking of SMTP submission...

Mark Andrews marka at isc.org
Fri Nov 28 00:38:24 UTC 2014


In message <CAArzuouvhnHo7BbAWUwiR3=m0x2O6Qe=2qLcvb29i07OaX-yqg at mail.gmail.com>
, Suresh Ramasubramanian writes:
> 
> Yes. Till that hotspots IP space gets blackholed by a major freemail
> because of all the nigerians and hijacked devices emitting bot traffic
> through stolen auth credentials.

Why would it black hole the address rather than the block the
compromised credentials?  The whole point of submission is to
authenticate the submitter and to be able to trace spam back to the
submitter and deal with the issue at that level of granuality.

Blocking at that level also stop the credentials being used from
anywhere.

scalpel vs chainsaw.

Just because you provide free email doesn't give you the right to
not do the service properly.  You encouraged people to use your
service.  You should resource it to deal with the resulting load
and that includes dealing with spam and scans being sent with stolen
credentials.  As a free email provider you have the plain text.

Mark

> There's other ways to stop this but they take actual hard work and rather
> more gear than a rusted up old asa you pull out of your closet as like as
> not.
>  On Nov 28, 2014 2:10 AM, "Mark Andrews" <marka at isc.org> wrote:
> 
> >
> > Which is why your MTA should always be setup to require the use of
> > STARTTLS.  Additionally the CERT presented should also match the
> > name of the server.
> >
> > There is absolutely no reason for a ISP / hotspot to inspect
> > submission traffic.  The "stopping spam" argument doesn't wash with
> > submission.
> >
> > Mark
> >
> > In message <54778167.7080808 at bogus.com>, joel jaeggli writes:
> > >
> > > I don't see this in my home market, but I do see it in someone else's...
> > > I kind of expect this for port 25 but...
> > >
> > > J at mb-aye:~$telnet 147.28.0.81 587
> > > Trying 147.28.0.81...
> > > Connected to nagasaki.bogus.com.
> > > Escape character is '^]'.
> > > 220 nagasaki.bogus.com ESMTP Sendmail 8.14.9/8.14.9; Thu, 27 Nov 2014
> > > 19:17:44 GMT
> > > ehlo bogus.com
> > > 250-nagasaki.bogus.com Hello XXXXXXXXXXXXXXX.wa.comcast.net
> > > [XXX.XXX.XXX.XXX], pleased to meet you
> > > 250 ENHANCEDSTATUSCODES
> > >
> > > J at mb-aye:~$telnet 2001:418:1::81 587
> > > Trying 2001:418:1::81...
> > > Connected to nagasaki.bogus.com.
> > > Escape character is '^]'.
> > > 220 nagasaki.bogus.com ESMTP Sendmail 8.14.9/8.14.9; Thu, 27 Nov 2014
> > > 19:18:33 GMT
> > > ehlo bogus.com
> > > 250-nagasaki.bogus.com Hello
> > > [IPv6:2601:7:2380:XXXX:XXXX:XXXX:c1ae:7d73], pleased to meet you
> > > 250-ENHANCEDSTATUSCODES
> > > 250-PIPELINING
> > > 250-8BITMIME
> > > 250-SIZE
> > > 250-DSN
> > > 250-AUTH DIGEST-MD5 CRAM-MD5 LOGIN
> > > 250-STARTTLS
> > > 250-DELIVERBY
> > > 250 HELP
> > >
> > > that's essentially a downgrade attack on my ability to use encryption
> > > which seems to be in pretty poor taste frankly.
> > --
> > Mark Andrews, ISC
> > 1 Seymour St., Dundas Valley, NSW 2117, Australia
> > PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org
> >
> 
> --bcaec517c6c01f783d0508e015a5
> Content-Type: text/html; charset=UTF-8
> Content-Transfer-Encoding: quoted-printable
> 
> <p dir=3D"ltr">Yes. Till that hotspots IP space gets blackholed by a major =
> freemail because of all the nigerians and hijacked devices emitting bot tra=
> ffic through stolen auth credentials. </p>
> <p dir=3D"ltr">There's other ways to stop this but they take actual har=
> d work and rather more gear than a rusted up old asa you pull out of your c=
> loset as like as not. <br>
> </p>
> <div class=3D"gmail_quote">On Nov 28, 2014 2:10 AM, "Mark Andrews&quot=
> ; <<a href=3D"mailto:marka at isc.org">marka at isc.org</a>> wrote:<br type=
> =3D"attribution"><blockquote class=3D"gmail_quote" style=3D"margin:0 0 0 .8=
> ex;border-left:1px #ccc solid;padding-left:1ex"><br>
> Which is why your MTA should always be setup to require the use of<br>
> STARTTLS.=C2=A0 Additionally the CERT presented should also match the<br>
> name of the server.<br>
> <br>
> There is absolutely no reason for a ISP / hotspot to inspect<br>
> submission traffic.=C2=A0 The "stopping spam" argument doesn'=
> t wash with<br>
> submission.<br>
> <br>
> Mark<br>
> <br>
> In message <<a href=3D"mailto:54778167.7080808 at bogus.com">54778167.70808=
> 08 at bogus.com</a>>, joel jaeggli writes:<br>
> ><br>
> > I don't see this in my home market, but I do see it in someone els=
> e's...<br>
> > I kind of expect this for port 25 but...<br>
> ><br>
> > J at mb-aye:~$telnet 147.28.0.81 587<br>
> > Trying 147.28.0.81...<br>
> > Connected to <a href=3D"http://nagasaki.bogus.com" target=3D"_blank">n=
> agasaki.bogus.com</a>.<br>
> > Escape character is '^]'.<br>
> > 220 <a href=3D"http://nagasaki.bogus.com" target=3D"_blank">nagasaki.b=
> ogus.com</a> ESMTP Sendmail 8.14.9/8.14.9; Thu, 27 Nov 2014<br>
> > 19:17:44 GMT<br>
> > ehlo <a href=3D"http://bogus.com" target=3D"_blank">bogus.com</a><br>
> > <a href=3D"http://250-nagasaki.bogus.com" target=3D"_blank">250-nagasa=
> ki.bogus.com</a> Hello <a href=3D"http://XXXXXXXXXXXXXXX.wa.comcast.net" ta=
> rget=3D"_blank">XXXXXXXXXXXXXXX.wa.comcast.net</a><br>
> > [XXX.XXX.XXX.XXX], pleased to meet you<br>
> > 250 ENHANCEDSTATUSCODES<br>
> ><br>
> > J at mb-aye:~$telnet 2001:418:1::81 587<br>
> > Trying 2001:418:1::81...<br>
> > Connected to <a href=3D"http://nagasaki.bogus.com" target=3D"_blank">n=
> agasaki.bogus.com</a>.<br>
> > Escape character is '^]'.<br>
> > 220 <a href=3D"http://nagasaki.bogus.com" target=3D"_blank">nagasaki.b=
> ogus.com</a> ESMTP Sendmail 8.14.9/8.14.9; Thu, 27 Nov 2014<br>
> > 19:18:33 GMT<br>
> > ehlo <a href=3D"http://bogus.com" target=3D"_blank">bogus.com</a><br>
> > <a href=3D"http://250-nagasaki.bogus.com" target=3D"_blank">250-nagasa=
> ki.bogus.com</a> Hello<br>
> > [IPv6:2601:7:2380:XXXX:XXXX:XXXX:c1ae:7d73], pleased to meet you<br>
> > 250-ENHANCEDSTATUSCODES<br>
> > 250-PIPELINING<br>
> > 250-8BITMIME<br>
> > 250-SIZE<br>
> > 250-DSN<br>
> > 250-AUTH DIGEST-MD5 CRAM-MD5 LOGIN<br>
> > 250-STARTTLS<br>
> > 250-DELIVERBY<br>
> > 250 HELP<br>
> ><br>
> > that's essentially a downgrade attack on my ability to use encrypt=
> ion<br>
> > which seems to be in pretty poor taste frankly.<br>
> --<br>
> Mark Andrews, ISC<br>
> 1 Seymour St., Dundas Valley, NSW 2117, Australia<br>
> PHONE: +61 2 9871 4742=C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=
> =A0 =C2=A0INTERNET: <a href=3D"mailto:marka at isc.org">marka at isc.org</a><br>
> </blockquote></div>
> 
> --bcaec517c6c01f783d0508e015a5--
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org


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