Tricky popup that got through

Usually Google Toolbar or Firefox's built-in popup blocker blocks these annoying pop-up ads, but this one got through when I was using a different computer. The pop-up looked like it might be an actual security-related screen from my browser (Firefox). The message in the text was convincing. The similarity to a Firefox window and the convincing message made me move my mouse toward the download button, but I thought twice and looked more closely at the dialog for clues since I'd never seen Firefox do this before. Then I noticed the originating URLs displayed in the corners. I saved a screenshot of it and drew in red on the image to reveal the deception. That button isn't a real button, it's just a picture of a button with an invisible link behind it.



If you click on the image above you can see it full size. Later I noticed in the small, faded text near the bottom of the window it says "All information in this advertisement (emphasis mine) courtesy SoftwareOnline.com, which is not affiliated with Microsoft Corporation."