Re: saslauthd attack

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On Wed, 2010-02-10 at 15:08 -0500, John Hinton wrote:
I'm seeing a lot of activity over the last two days with what looks to 
be a kiddie script. Mostly trying to access several of our servers with 
the username anna. All failed... in fact I don't think we have a user 
anna on any of our servers. Meanwhile...

I'm running Sendmail. This pertains to Centos 4 and 5 servers. I'm also 
running fail2ban on some and Ossec on others. So far, no blocking is 
being done. When I look at the logs all I find is under messages and 
here is a sample:

Feb 10 05:23:08 neptune saslauthd[3370]: do_auth         : auth failure: 
[user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
Feb 10 05:23:25 neptune saslauthd[3369]: do_auth         : auth failure: 
[user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
Feb 10 05:23:58 neptune saslauthd[3370]: do_auth         : auth failure: 
[user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
Feb 10 06:56:53 neptune saslauthd[3370]: do_auth         : auth failure: 
[user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
Feb 10 06:56:54 neptune saslauthd[3368]: do_auth         : auth failure: 
[user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
Feb 10 06:56:55 neptune saslauthd[3370]: do_auth         : auth failure: 
[user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]
Feb 10 06:56:59 neptune saslauthd[3368]: do_auth         : auth failure: 
[user=anna] [service=smtp] [realm=] [mech=shadow] [reason=Unknown]

So, I can't write a rule to block this attack as I can't find any IP 
address to block. I've looked and googled til my eyes are red and can't 
find where to set logging in saslauthd or where ever it needs to be set 
to record the IP address generating these failures. Does anyone have an 
idea?

Also, some may wish to do a grep 'do_auth' on messages to see if this is 
happening to you. They sometimes come in rapid succession.

John Hinton
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In my case the last one was on 19th of January, and came from an IP in China 118-167-9-72.dynamic.hinet.net [118.167.9.72]. Took it from /var/spool/maillog.

Actually I'm running Postfix with sasl, and the portion of maillog I was looking for was: SASL LOGIN authentication failed. Don't know how it will be on sendmail, though.

HTH,


Calin

Key fingerprint = 37B8 0DA5 9B2A 8554 FB2B 4145 5DC1 15DD A3EF E857

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