Microsoft offered unspecified security concerns as the sole reasons behind a move made with the third service pack for Office 2003, which has resulted in the blocking of certain file formats following the installation of Office 2003 SP3. The vast majority of items disallowed by the service pack are Microsoft legacy file formats, but there is also an exception: CorelDraw .CDR files. The Redmond company failed to offer any additional explanations for its decision.  "By installing Office 2003 SP3, the ability to open and save older legacy file formats will be blocked. The reason for this decision is strictly for security reasons. Some older file formats including some from Microsoft are insecure and do not satisfy new attack vectors that hackers can use to execute malicious code. The decision to block the formats is strictly to protect your machine from being compromised", explained Viral Tarpara, Microsoft IT Pro Evangelist – UK.

Tarpara informed that the following formats have been disabled with the implementation of Office 2003: Lotus and Quattro Files (.wk1, .wk4, .wj3, wk1 FMT, .wks, .wk3, wk3 FM3, .wj2, .wq1, .fm3, .wj10), Dif and Sylk Files (.dif, .slk) as well as Files Before PowerPoint97 (.ppt, .pot, .pps, and .ppa.). "I would personally convert your documents to OpenXML by using the Office Compatibilty Pack for Office XP,2000,2003. If you need to batch convert ALL of your files to the new format, Microsoft provides an easy to use command-line tool for IT administrators called Office Migration Planning Manager (OMPM)", Tarpara added. But of course that the conversion is simply an unrealistic scenario for corporate users that have to deal with thousands if not millions of files. For just such a case, Microsoft has published KB article 938810 that offers guidance on how to perform a variety of registry hacks in Windows, in order to regain access to the file formats that have been blocked with Office 2003.