Schneier on Security

OpenDocument Format and the State of Massachusetts

OpenDocument format (ODF) is an alternative to the Microsoft document, spreadsheet, and etc. file formats. (Here’s the homepage for the ODF standard; it’ll put you to sleep, I promise you.)

So far, nothing here is relevant to this blog. Except that Microsoft, with its proprietary Office document format, is spreading rumors that ODF is somehow less secure.

This, from the company that allows Office documents to embed arbitrary Visual Basic programs?

Yes, there is a way to embed scripts in ODF; this seems to be what Microsoft is pointing to. But at least ODF has a clean and open XML format, which allows layered security and the ability to remove scripts as needed. This is much more difficult in the binary Microsoft formats that effectively hide embedded programs.

Microsoft’s claim that the the open ODF is inherently less secure than the proprietary Office format is essentially an argument for security through obscurity. ODF is no less secure than current .doc and other proprietary formats, and may be—marginally, at least—more secure.

This document document from the ODF people says it nicely:

There is no greater security risk, no greater ability to “manipulate code” or gain access to content using ODF than alternative document formats. Security should be addressed through policy decisions on information sharing, regardless of document format. Security exposures caused by programmatic extensions such as the visual basic macros that can be imbedded in Microsoft Office documents are well known and notorious, but there is nothing distinct about ODF that makes it any more or less vulnerable to security risks than any other format specification. The many engineers working to enhance the ODF specification are working to develop techniques to mitigate any exposure that may exist through these extensions.

This whole thing has heated up because Massachusetts recently required public records be held in OpenDocument format, which has put Microsoft into a bit of a tizzy. (Here are two commentaries on the security of that move.) I don’t know if it’s why Microsoft is submitting its Office Document Formats to ECMA for “open standardization,” but I’m sure it’s part of the reason.

Tags: computer security, Microsoft, obscurity, open source

Posted on December 7, 2005 at 2:21 PM • 14 Comments