Why is this a hidden filename extension?

Mark Sapiro mark at msapiro.net
Sat Sep 19 17:05:54 IST 2009

On Fri, Sep 18, 2009 at 11:43:08AM -0600, Robert Lopez wrote:
> Report: MailScanner: Attempt to hide real filename extension (Motion
> %26 Order.doc)

I just did some tests, and it appears if the original filename is

  Motion & Order.doc .doc

with at least one space between the two '.doc's, it will (correctly)
match the "Attempt to hide real filename extension" rule, but
MailScanner will drop the spaces and the second .doc from the name.

This definitely has to do with the presence of the & in the name. Here
are a few test results:

    Actual name                  Reported name
Motion & Order.doc .doc      Motion %26 Order.doc
Motion&Order.doc .doc        Motion%26Order.d.doc
Motion - Order.doc .doc      Motion - Order.doc .doc

So it appears that in your case, there actually was a double extension,
and that in the process of 'html escaping' the name, the second extension
was dropped. If the entire message is in the quarantine (Quarantine Whole
Message = yes), you can see the original file name there.

Mark Sapiro mark at msapiro net       The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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