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From "Dennis E. Hamilton" <dennis.hamil...@acm.org>
Subject Implications for security vulnerability (CVE-2012-0037)
Date Fri, 23 Mar 2012 04:46:07 GMT
Here is my personal assessment around the CVE-2012-003 that was announced concurrent with a
patch release for OpenOffice 3.3.0 today.

First, the vulnerability is related to use of ODF 1.2 document format in a manner that causes
information from the user's computer to be covertly accessed and captured inside the document
when it is saved.  (If it is not saved, there is no harm.  If it is saved as ODF 1.0/1.1,
there might also be no harm, although this case requires some testing to confirm.)

As was reported, it is relatively easy to craft an ODF 1.2 document that can exercise the
exploit when opened by a vulnerable application.

THE EXTENT OF THE VULNERABILITY

LibreOffice reported CVE-2012-0037 today concurrent with the agreed lifting of the embargo.

My understanding is that later (since January) LO 3.4.x releases have the fix as do the LO
3.5.x releases and release candidates.  Consult the LibreOffice.org site and blog for details.

All LibreOffice releases preceding those identified as repaired remain vulnerable.

The patched versions of OO.o 3.3.0 and Oracle OO.o-dev 3.4, are free of the vulnerability.
 The latest (since March 1) Apache OpenOffice developer previews are free of the vulnerability.

All previous OpenOffice.org releases back to OO.o 3.0 presumably have the vulnerability (since
that was the start of claimed ODF 1.2 support).  Any unpatched recent versions will continue
to have the vulnerability until patched or replaced, of course.  

OTHER RELEASES/PRODUCTS THAT DO NOT HAVE THE VULNERABILITY

Pre-3.0 versions of OO.o should not have the vulnerability.

Lotus Symphony has never had the vulnerability.

Microsoft Office 2007/2010 ODF support does not have the vulnerability.  Microsoft Office
converters from ODF to Office (as used with Office 2003, for example) do not have the vulnerability.
 

I suspect that documents containing the exploit can't pass through Google Docs, but I haven't
tested it.  I doubt that they are vulnerable though.

Some other supporters of ODF format have indicated that their products do not support the
feature of ODF 1.2 format that is the carrier of the exploit.  The suppliers of such products
should be consulted directly for confirmation.

DOCUMENTS NOT HAVING THE EXPLOIT

Documents saved as ODF 1.0/1.1 should not preserve any exploit.  That is a way to scrub suspicious
documents and templates so long as any loss of fidelity is tolerable when going down-level
and back.
 
Documents saved as .doc, .rtf, .docx, .xls, .xlsx, .ppt, .pptx, etc., and then brought back
from those formats should not contain any exploit.  This only works if any loss of fidelity
is tolerable of course.  Note that it is not necessary to have Microsoft Office.  Using the
converters that are part of OpenOffice.org, Apache OpenOffice, and LibreOffice is sufficient.
 

Saved HMTL documents will, likewise, be stripped of any exploit.  Saved PDF documents will
also be exploit-free so long as the form of PDF that preserves the original ODF document as
an "attachment" is not used.

WHO IS VULNERABLE AND WHAT TO DO IF YOU THINK YOU ARE

The exploit requires that you open and use a document or template from an unreliable or unknown
source (or that someone you do trust has managed to do this and sent the result to you). 
The captured material is no use if the resulting saved document is not returned to someone
who knows to look for it.  In some forms of the exploit, once information is captured, there
are no further captures.  However, the captured content can be passed on through subsequent
revisions and recipients.  That is, there may be perpetuation of covertly-captured residue.

Fortunately, the exploit involves a feature that is not required for the correct processing
of most ODF documents (which is also why success of the exploit is easily unnoticed).  So
extinguishing the feature from a document, while heavy handed, rarely does any harm.

If you have any doubt concerning ODF documents in your possession, you can exercise some of
the remedies in the previous section, involving saving the document in different formats and
then re-opening it form those formats.  

If you are unable to patch your system or want to ensure that documents you already have do
not carry any exploit, you can also clean up the ODF package using a Zip utility.  It is also
possible to produce a utility that can automatically scrub most ODF packages of any potentially-suspect
content.  

 - Dennis




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