[OT] HELP!!! mail attack

[Rodolfo Alcazar Portillo]

Am Mittwoch, den 26.03.2008, 05:12 -0700 schrieb Craig White:
> That account has likely been 'Joe Jobbed' and you are seeing the
> backscatter. Google 'Joe Job' or find it on Wikipedia for an
> explanation.

Great. Seems precisely the problem.

> My first 'defense' is greylisting, run as a policy in postfix.

The same, I have greylistings activated sometime ago. Works great.
Except for bounces, which usually come from real and valid servers.

> My second defense is to use rbl's (abuseat / spamhaus / dsbl) to
> otherwise block KNOWN blacklisted sources

Already activated.

> My third defense is to require:
>  - reverse DNS of sender
>  - fqdn of sender
>  - valid hostname
>  - valid recipient

Ok. I will try these.

> Once I have accepted e-mail, it is shuffled to 'MailScanner' which is a
> wrapper program that sends e-mail through clamav and then through
> spamassassin, where it is cleaned and scored.

I have the same. The problem is that I received so many mails to that
account, until /var/spool/mqueue.in became flooded. 

> Finally, I have 'sieve' rules for all users which puts high spam score
> e-mails into a users 'SPAMBOX' folder of which everything that is older
> than 7 days is automatically cleaned out.

Thanks a lot, you gave us a lot of lights on how to approach the
problem. We are working on finding a pattern to filter the emails, but
until now, nothing. You can see the word* files from a lot of messages
here (trying to find IPs and so on):

http://www.padep.org.bo/log20080325/log/

:)
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Rodolfo Alcazar - rodolfo.alcazar at padep.org.bo
otbits.blogspot.com / counter.li.org: #367962
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