Security firm Sophos on Tuesday indicated that a surprisingly high level of malware has been found on Mac computers — the firm’s research revealed that one in every five Mac computers is harboring some kind of Windows malware. Of the 100,000 customers sampled through Sophos’s antivirus offerings, 20% of users were found to be carrying one or more instances of Windows malware. The firm highlighted that Windows malware on a Mac won’t cause any harm, however, unless the computer also runs a Windows partition in addition to OS X. The company’s research found that just 2.7% of Macs that installed the company’s free anti-virus software were infected by OS X malware. Nearly all of the OS X malware discovered was an iteration of the “Flashback” trojan called “Flshplyr.” Sophos said that cybercriminals may find Macs to be targets because OS X users are less likely to be running an anti-virus software, however Macs can get viruses and the right software can keep a user’s computer safe. A second pie chart follows below.