Potential issue with docx format and Clam

Martin Hepworth maxsec at gmail.com
Mon Apr 20 13:47:23 IST 2009

what happens if you use Clamd rather than the module so you can update
quicker (no reliance on module maintainers releasing a new version) and MS
children are smaller and startup faster?

Martin Hepworth
Oxford, UK

2009/4/20 Jeff A. Earickson <jaearick at colby.edu>

> Julian,
> I'm forwarding along a note from our support desk people, who seem to
> have uncovered an issue with Office 2007/2008 docx file formats and
> the ClamAV recursion level.  In my case, I am running MS 4.75.9-2 with
> ClamAVmodule Maximum Recursion Level = 8
> Adam's detective work below suggests that this setting may be too low
> for Office 2007/2008 docx attachments.  Anybody else seen this?
> (Time for me to upgrade to the latest stable version, or the latest beta).
> Jeff Earickson
> Colby College
> ---------- Forwarded message ----------
> I did some experimenting with this situation [rejections of email with
> "Report: MailScanner: Message contained archive nested too deeply" messages]
> and here is what I found:
> - As you may or may not know the new Office 2007/2008 file format is really
> just a renamed .zip file containing other files and folders that make up
> the
> document.
> - If you insert an object into a .docx that is, for instance, a PowerPoint
> slide it is inserted as a .pptx (again, just a .zip with a different
> extension).
> - If that slide contains an inserted Excel table, it is inserted as a .xlsx
> (.zip).
> - So if you add all those up you have the original .docx, which contains a
> folder called "embedded", in that folder is a .pptx file, inside that is a
> folder called "embedded", in that folder is a .xlsx file, inside that is a
> series of files and folders.  So all that added up is 7 layers.
> I was able to duplicate Todd's error with my own .docx, .pptx and .xlsx,
> but
> I noticed that it had to be all three.  If I tried to email a .docx with
> just a PowerPoint slide embedded it went fine.  And if I tried to email a
> .pptx with an embedded Excel Table that went fine too.  So it seems as
> though we may need to adjust some settings on MailScanner to allow for this
> type of file to pass because as we convert more and more people to Office
> 2007/2008 we are going to be more likely to run into these types of
> situations.
> ------------
> Adam Nielsen
> Faculty and Staff Support Center
> x4222
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