It’s a digital-age rule of thumb: Computers running on unsupported operating software are more likely to be hacked than those whose system security is up-to-date. Yet a surprising number of businesses and government agencies were still using the Windows 7 operating system just before Microsoft halted free security updates last month. Monitoring of roughly 60,000 organizations by the cybersecurity ratings company Bitsight found nearly 70% still using Windows 7 to some degree. Large organizations with more than 10,000 employees were even worse. Nine in 10 still had the nine-year-old operating system on some machines. In more than 40 percent of large finance and healthcare institutions — and about a third of large government and political outfits — at least one in four employees were still running Windows 7. Bitsight data science director Tom Montroy doesn’t believe much migration has occurred since his firm’s data collection, which covered global organizations but skewed to the U.S. due to European Union restrictions. Microsoft is offering paid support for professional and enterprise versions of Windows 7 for another three years.