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Re: Plaintext base64 error.hta attachment

2003-05-31 03:07:53
On Fri, May 30, 2003 at 09:21:37PM -0700, procmail(_at_)deliberate(_dot_)net 
wrote:

      I just got several extremely nasty looking emails all of
which just now snuck by my otherwise 100% accurate attachment
filters. 

Not sure why they made it past the old virus checker that Phillip
Guenther posted four or five years ago.  I use a revised version
of it to this day, as one of my only two virus recipes.  It caught
your sample fine in my test harness.  I have yet to see a virus get
by both the virus recipes.  Here's the one in question, so you
can stop reinventing the wheel:


 :0  # 030403 () based loosely on an original from Philip Guenther
  * $           $GO^0    ^Content-[^$WS]+:.*=$DQ?[^$DQ]*\.$NASTYEXT
  * $         $STOP^0  !  CTYPE ?? ^^multipart
  * $  B  ??    $GO^0    ^Content-[^$WS]+:.*($[$WS].*)*=[$WS]*($[$WS]+)*$DQ?\
                                          [^$DQ]*\.$NASTYEXT
   { RX = "${RX:+$RX, }VIR_01" }

$GO is an oversaturated "infinity" of 9876543210.  $STOP is its negative.
$CTYPE contains the Content-Type: header, which I save early on in my rc.
$DQ is a var containing only a double-quotation mark (my editor otherwise
does ugly things if I view them raw, is why).  $WS is whitespace -- a
space and a tb.  $NASTYEXT is currently this for me:

 NASTYEXT     = (hta|pif|scr|shs|vb[se]|ws[fh]|(doc|txt|xls)\\.)

Suggest you add exe and bat and a few more things that I left off
of mine on purpose.  Anyway, the recipe caught your sample.  Here
is my (non-verbose, but highly customized) log output from my
test harness.

 11:45am [~/Mail] 270[1]> rctest testvir

    
     >>>>> START LOG FOR NEW MESSAGE [LOGFILE: 030531] <<<<< 
    
    
      : We're exiting Section ENV 
      : We're entering Section DO_ME_FIRST 
    
    
         >> HOST is munged5.munged.com << 
    
    
      : We're exiting Section DO_ME_FIRST 
      : We're entering Section MY_DOMAINS 
    
         ===> DOM is >munged.com<
    
      : We're exiting Section MY_DOMAINS 
      : We're entering Section HEADERS 
    
         ===> FROM is >Mail Delivery Subsystem 
<MAILER-DAEMON(_at_)yahoo(_dot_)com><
         ===> LOCALPART is >MAILER-DAEMON<
         ===> SUBJECT is >Mail Delivery Error [jgKFiTkayUraLHgG]<
         ===> TO is >Don <don(_at_)EXAMPLE(_dot_)COM><
         ===> CC is not present
         ===> MSGID is ><417DB4175D6K7801(_at_)yahoo(_dot_)com><
         ===> DH is >MISSING!<
         ===> FOGGYCLIENT is ><
         ===> CTYPE is >multipart/mixed<
    
      : We're exiting Section HEADERS 
      : We're entering Section VIRUS 
    
          > Recipe-ID: VIR_01 < 
    
    From MAILER-DAEMON(_at_)yahoo(_dot_)com Sat May 31 02:14:53 2003
 Subject: Mail Delivery Error [jgKFiTkayUraLHgG]
  Folder: 

Hope that helps.

Dallman

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