Oh it depends on the numbers. Just how many legitimate smtp submission attempts do you get from say an access point at Joes diner in nowhere, OH? Versus just how many password cracking and malware relay attempts across how many of your users, from an unpatched xp box the guy is using for a billing app? At the scale of the problem a provider with any kind of userbase faces, you need a chainsaw, not a scalpel, given that you're out to cut a tree rather than perform plastic surgery. On Nov 28, 2014 6:08 AM, "Mark Andrews" <marka@isc.org> wrote:
In message <CAArzuouvhnHo7BbAWUwiR3=m0x2O6Qe= 2qLcvb29i07OaX-yqg@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@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@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@mb-aye:~$telnet 147.28.0.81 587 Trying 147.28.0.81... Connected to nagasaki.bogus.com. Escape character is '^]'. 220 nagasaki.bogus.com ESMTP Sendmail 8.14.9/8.14.9; Thu, 27 Nov 2014 19:17:44 GMT ehlo bogus.com 250-nagasaki.bogus.com Hello XXXXXXXXXXXXXXX.wa.comcast.net [XXX.XXX.XXX.XXX], pleased to meet you 250 ENHANCEDSTATUSCODES
J@mb-aye:~$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@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"= ; <<a href=3D"mailto:marka@isc.org">marka@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@bogus.com ">54778167.70808= 08@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@mb-aye:~$telnet 147.28.0.81 587<br> > Trying 147.28.0.81...<br> > Connected to <a href=3D"http://nagasaki.bogus.com" target=3D"_blank">n= agasaki.bogus.com</a>.<br> > Escape character is '^]'.<br> > 220 <a href=3D"http://nagasaki.bogus.com" target=3D"_blank">nagasaki.b= ogus.com</a> ESMTP Sendmail 8.14.9/8.14.9; Thu, 27 Nov 2014<br> > 19:17:44 GMT<br> > ehlo <a href=3D"http://bogus.com" target=3D"_blank">bogus.com </a><br> > <a href=3D"http://250-nagasaki.bogus.com" target=3D"_blank">250-nagasa= ki.bogus.com</a> Hello <a href=3D"http://XXXXXXXXXXXXXXX.wa.comcast.net" ta= rget=3D"_blank">XXXXXXXXXXXXXXX.wa.comcast.net</a><br> > [XXX.XXX.XXX.XXX], pleased to meet you<br> > 250 ENHANCEDSTATUSCODES<br> ><br> > J@mb-aye:~$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@isc.org">marka@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@isc.org