Its very common lately for sites spreading malware from ads. The ad which are served from Google and Microsoft may relie on third party syndication may potentially be compromised which may lead to malware distribution. A similar incident happened as reported by Kaspersky that the largest website of sweden was spreading scare-ware to its users.
The malware was detecting the brower and anyone using Internet Browser were targeted with this attack. The malicious ad only triggered when a user visits the website using Internet Explorer.
When a user visits Aftonbladet .com using Internet Explorer the user will get redirected to a malicious website, hxxp:// [badguy] . windowsdefence-sn.nl on this page a static image of a fake warning from Microsoft Security Essentials that they have detected viruses on your computer, and you need to fix it – says David from Kaspersky.
It was a shareware showing picture similar to Microsoft Security Essentials. When a user click on the picture , the user actually downloads the malicious file infecting the system. The file obtained by Kaspersky was obfuscated Executable and they are researching the details surrounding it.
