Bit9 sells application whitelisting software and services, giving it some incentive to highlight applications that could be better controlled through its products.
Firefox leads Bit9's list, followed by Adobe Flash & Acrobat; EMC VMware Player, Workstation, and other products; Sun Java Runtime Environment; Apple QuickTime, Safari, and iTunes; Symantec Norton products; Trend Micro OfficeScan; Citrix products; Aurigma and Lycos image uploaders; Skype; Yahoo Assistant; and Microsoft Windows Live Messenger.
Bit9 ranks the applications according to popularity, the number and severity of vulnerabilities, and the difficulty of detecting and patching those vulnerabilities for IT administrators.
Many, if not all, of the cited vulnerabilities have been patched, but Bit9's list is meant to highlight the fact that these patches aren't easily deployed by IT administrators, who many not even know what programs employees are running.
Criteria for inclusion on the list include: running under Windows and not being centrally updatable via enterprise tools such as Microsoft SMS and WSUS. This could be said to put Apple software at a disadvantage and to unfairly keep Microsoft products, many of which have been designed to work with patch management systems, off the list.
Nonetheless, there's some value to Bit9's exercise in that companies have to come to terms with the fact that many employees flout IT department rules about authorized software, often with good reason. It also serves to highlight the warnings of many security experts in recent years that malware authors are focusing increasingly on the application layer.