Even though it's not the first time, Yahoo and Bing have been caught again serving malware through their advertised results, and this time the malicious element involved is the infamous Sirefef, also known as ZeroAccess and Max++.
GFI Labs blog reveals that the cybervillains have changed the malevolent file that was supplied through a compromised website, probably to clean their tracks, but before the clean-up operation internauts could have been faced with an innocent looking page that promised to “bring their web pages back to life.”
If anyone searched to download Adobe Flash, they might have ended up downloading Flash Player 10 Setup.exe, which according to VirusTotal is nothing short of the worst virus around.
The virus is dangerous because it's really difficult to clean, so make sure to protect your computer if you're using Bing or Yahoo to look for apps.