Computers running Windows 8 had the highest rate of protection, with just 8.1 percent of computers running the 32-bit edition and 7.0 percent of computers running the 64-bit edition lacking up-to-date real-time protection. Windows 8 includes real-time antimalware and antispyware protection by default,2 which is likely a significant factor in the reduced number of Windows 8 computers not running security software; previous releases of Windows did not include real-time antimalware software by default. In addition, Windows 8 was only generally available for slightly more than two months of the half-year period, which provided less of an opportunity for real-time protection to expire or to be disabled by computer users or by malware.
Among supported releases of Windows, the lowest rate of protection was observed on computers running the RTM version of Windows 7, of which 32.3 percent of computers running the 32-bit edition and 28.2 percent of computers running the 64-bit edition lacked up-to-date real-time protection. Computers running Windows 7 SP1, the most recent service pack available for Windows 7, were significantly less likely to lack real-time protection than computers running the RTM version.