Ars Technica: Security vendor Intego has issued a warning about a two-year-old Windows spyware app that has migrated to the Mac. OS X users are unknowingly downloading "OSX/OpinionSpy" when they download screensavers or shareware programs.
Intego warns that the spyware could be used to collect personal information, such as "user names, passwords, credit card numbers, web browser bookmarks, history and much more."
Removing the screensaver or other app that contained the spyware won't eliminate the problem. Instead, Intego recommends commercial malware-removal tools.