The US-CERT (Computer Emergency Readiness Team) (a division of the Department of Homeland Security) recently published an advisory to immediately ditch Apple’s QuickTime product on Windows systems. They cited a blog post from Trend Micro, which noted that Apple has dropped security updates for the product on Windows, and that there are known security holes being exploited.
To be clear, QuickTime for Mac OS X on Apple Macintosh systems is still a supported product.
You may not recall installing QuickTime on your system, but it is often bundled with third-party applications. I personally found the timing of this ironic, as I had just installed QuickTime as part of my GoPro Studio camera software just two days before the announcement. Be sure to look in your system’s Control Panel and see if you have QuickTime, and remove it.