Re: [Exim] Help with Exim 4.x & System Filter

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Author: dman
Date:  
To: exim-users
Subject: Re: [Exim] Help with Exim 4.x & System Filter
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On Wed, May 08, 2002 at 12:00:45PM +0200, Tirone Nel wrote:
| Its the default filter I downloaded from the Exim site. But yes, it runs
| along those lines.

|
| This is basically it:
| if $header_content-type: matches
| "(?:file)?name=(\"[^\"]+\\\\.(?:ad[ep]|ba[st]|c
| hm|cmd|com|cpl|crt|eml|exe|hlp|hta|in[fs]|isp|jse?|lnk|md[be]|ms[cipt]|pcd|p
| if|r
| eg|scr|sct|shs|url|vb[se]|ws[fhc])\")"
| then
|   fail text "This message has been rejected because it has\n\
|              potentially executable content $1\n\
|              This form of attachment has been used by\n\
|              recent viruses or other malware.\n\
|              If you meant to send this file then please\n\
|              package it up as a zip file and resend it."
|   seen finish
| endif

|
| Looks like it should work, right?


Not for Klez. Note that (as the comments say) the filter only checks
the Content-Type: header. It should work for single-part messages,
but klez sends itself as a multipart mime message.

| Has anyone else got it to work with Exim 4? And if so, could I have
| a look at their configuration file?


I use this to block klez :


if
    "$message_body $message_body_end"
        matches "Content-.*audio/x-wav.*\.(?:pif|exe)"
    or
    "$message_body $message_body_end"
        matches "Content-.*audio/x-mid.*\.(?:scr|exe)"
    or
    "$message_body $message_body_end"
        matches "<iframe.*</iframe>"
then
  fail "<<(sender: $sender_address) (From: $h_From:)>> \
         This message has been rejected because the body contains \n\
         text that appears to be MIME Content-Type: headers used by KLEZ.\n\
         If you intended to send the file then please gzip it and resend it."
  seen finish
endif



-D

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A: If you have a problem with commercial software you can call a phone
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