MS Doesn't completely block spam with faulty attachments
mailscanner at joolee.nl
Thu Sep 1 18:06:28 IST 2011
The problem with the current spam is that they're blocked for containing exe
files, not double file extensions (Although they woul've hit that one if
exe's were not clocked.)
Only quick temporary solution is to disable all file-name validation because
this can occur with more than just exe files and double extensions. This is
no final solution though.
On 1 September 2011 18:40, Kevin Miller <Kevin_Miller at ci.juneau.ak.us>wrote:
> Easiest thing to do in that case is to comment out the line in
> filename.rules.conf that disallows double extensions. The message will be
> accepted as normal and go through the additional tests (is it an executable,
> is it a virus, is it spam, etc.)
> Kevin Miller Registered Linux User No: 307357
> CBJ MIS Dept. Network Systems Admin., Mail Admin.
> 155 South Seward Street ph: (907) 586-0242
> Juneau, Alaska 99801 fax: (907 586-4500
> *From:* mailscanner-bounces at lists.mailscanner.info [mailto:
> mailscanner-bounces at lists.mailscanner.info] *On Behalf Of *Joolee
> *Sent:* Thursday, September 01, 2011 7:32 AM
> *To:* MailScanner discussion
> *Subject:* Re: MS Doesn't completely block spam with faulty attachments
> I agree that it isn't a good idea to notify the sender of a spam or virus
> message I'm not planning to do that, I know the troubles of backscatter.
> What I've configured is that if a user sends a completely normal
> (non-virus, non-spam) E-mail but with, for instance, a file named
> "CurriculumVitae.doc.pdf" (default output for a lot of PDF printers). The
> server sends out a warning to sender and the original message stripped of
> it's attachment to the recipient of the message. Notifying the sender is not
> strictly necessary but if this is only done for such non-virus, non-spam
> message, it isn't a problem either.
> The situation that bugs me is when some spam message with a file named
> "CurriculumVitae.doc.pdf" is received. The message hits the filename rule
> and* isn't processed any further to check if its a spam message*. Because
> it isn't processed any further, the warning messages are send out to both
> sender and original recipient.
> As I stated before, I can disable the sender notification. What I can't do
> is tell my customers (the recipients) that such wrongly named files, most
> containing important documents, are silently discarded. Sending spam to my
> customers that could have been recognized isn't an option either.
> The simplest solution, I think, would be to *continue processing* the
> message after a file name rule is hit, decide if the E-mail is HAM and in
> that case, send out the notifications. If the E-mail is spam, silently
> discard it.
> It would add a bit of load to the server but stopping spam is what it's all
> about, isn't it? :P
> On 1 September 2011 16:34, Julian Field <MailScanner at ecs.soton.ac.uk>wrote:
>> He's probably switched on some "Notify Senders" options. Bad idea :-(
>> On 01/09/2011 12:32, Martin Hepworth wrote:
>>> what version of MS?
>>> I never inform the sender of junk as you end up with fake messages sent
>>> Martin Hepworth
>>> Oxford, UK
>>> On 1 September 2011 08:17, Joolee <mailscanner at joolee.nl <mailto:
>>> mailscanner at joolee.nl>**> wrote:
>>> Hallo Everybody,
>>> I've experienced a small flood of virus E-mails. These E-mails
>>> (subj.: "ACH Payment *random number* Canceled") contain
>>> attachments named like: "report_082011-65.pdf.exe"
>>> They obviously get blocked by the "no executables" and "No double
>>> file extensions" rules. The problem is that after blocking them,
>>> an automated E-mail is send to the original recipient and the
>>> (faked) sender of the message, informing them of the blocked
>>> Had the E-mails been processed further, they would've probably hit
>>> the virusscanner (not tested) or spamassassin (gives a score of 27
>>> when tested) and the E-mail would've silently been discarded as a
>>> virus / spam / phishing.
>>> Is it possible to let the MailScanner continue it's processing
>>> when hitting the file name rules and / or running the filename
>>> rule at a later time?
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>>> Julian Field MEng CITP CEng
>>> Buy the MailScanner book at www.MailScanner.info/store
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>>> 'It's okay to live without all the answers' - Charlie Eppes, 2011
>>> 'All programs have a desire to be useful' - Tron, 1982
>> This message has been scanned for viruses and
>> dangerous content by MailScanner, and is
>> believed to be clean.
>> MailScanner mailing list
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