Hello Pi-Web,

Absolutely. We like community developed tools :-)

Zip up the tool, source, readme et al and send it to support@ attached
to an email. Put the description you would like to see in the text of
your email. We'll add it to our site.

Thanks!

_M

Friday, January 4, 2008, 5:28:46 PM, you wrote:

> Hi

> I got a tool to test all messages in a folder with SNF.
> All with a non zero result is moved to a spam folder.

> Its like 84 lines of delphi code.
> If Pete will host the files I will supply the tool for free including source.


>> Friday, January 4, 2008, 4:56:29 PM, you wrote:
>> 
>>> Hello
>> 
>>> I got a strong attack today, over thousand messages at the same time!!
>>> The usual technique:
>>> Impersonate the victim and send to non valid users of one domain of
>>> mine!!
>>> Changing IP for each message.... UNBELIEVABLE!!
>> 
>> This is very common these days. We call it getting caught in the
>> light.
>> 
>> Our spamtrap server is currently experiencing a similar "attack" and
>> is seeing 1850+ messages per minute. Luckily we've killed this
>> particular campaign a few hours ago so leakage is only 7/min and
>> 890+/min of these messages are being truncated (scan stopped based on
>> IP via GBUdb)
>> 
>>> The only solution was, to stop all the services and move all the spool
>>> files in a temp directory.
>> 
>>> I won't use the "nobody" alias because at least the iMail Access Control
>>> can stop some bad IPs.
>> 
>>> My config is:
>>> Imail 9.23
>>> Mxguard 3.1
>>> Message Sniffer
>>> InvURIBL 3.7
>> 
>>> Two questions:
>> 
>>> 1) There is a way or tool to recycle back good messages from the temp
>>> directory into the queue?
>> 
>> You should be able to write a cmd script to test the messages in your
>> temp folder against SNF and place the clean messages back into the
>> spool for delivery. This doesn't give you a complete solution, but it
>> is reasonably viable in such cases.
>> 
>> I've not heard of it, but you may be able to find or write a similar
>> utility to put the temp messages through the entire scan process at
>> some reasonable pace -- You might ask DG about that - I'm not sure
>> what would be the best way to go about that w/ mxGuard and he may have
>> a solution already or know where it's buried.
>> 
>> Side Note:
>> 
>> We actually have a technology that we've simulated and not deployed
>> called Gauntlet. Under certain conditions messages are shunted to a
>> waiting area where their scanning and delivery are delayed for a
>> period of time so that filtering systems can "catch up"... For
>> example, messages that arrive from completely unknown IPs would have
>> to "run the gauntlet" before being delivered. The sensitivity of the
>> shunting system could be guided by "storm data" (B and C counts) from
>> GBUdb to reduce the possibility of delaying ordinary messages.
>> 
>> What you are describing is a manual version of this process.
>> 
>>> 2) How can I reduce or block(!) this kind of attacks?
>> 
>> The new version of SNF is very good at reducing this kind of attack
>> because the GBUdb component frequently can identify bad IP sources
>> very quickly after a new campaign begins and is able to block many of
>> the messages based on the IP reputation information known by the
>> network. In some cases this might include substantially all of the
>> attack prior to new pattern rules reaching your system -- in all cases
>> at least some fraction of the attack would be identified (based on
>> observations). The system will become more sensitive as more systems
>> begin using the new software -- at this time it is remarkably
>> sensitive even though only a small fraction of SNF users are already
>> using it -- so we expect significant improvements.
>> 
>> In this case, for example, many of the messages arriving would be seen
>> by SNF, identified after a very short scan (only the first few hundred
>> bytes), and then most-likely deleted (depending on how you tune your
>> system; also I'm not sure what options are available from mxGuard w/
>> regard to preempting additional tests and/or test ordering).
>> 
>> Given your system's configuration I don't know of any way to block
>> this kind of attack without adding additional components. A couple
>> that come to mind are SPF checking (so that any message pretending to
>> come from your domains must actually be coming from your servers
>> before being accepted), and graylisting which, while sometimes
>> problematic, currently provides some pretty good protection against
>> dumb-bot attacks. (Note that the newer bot softwares out there easily
>> defy gray listing so it's effectiveness is dropping quickly)
>> 
>> Hope this helps,
>> 
>> Best,
>> 
>> _M
>> 
>> --  Pete McNeil Chief Scientist, Arm Research Labs, LLC.
>> 
>> 
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>> 





-- 
Pete McNeil
Chief Scientist,
Arm Research Labs, LLC.


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