You visit a site that insurance or do a search on your favorite tool and thinks it's okay. Not necessarily. According to security firm Avast, an epidemic was identified virtual sites using banners harmful. And provided by companies like Yahoo, Google and Fox.

According to the blog of Avast, this is probably the biggest case ever recorded use of ads to infect your computer s, "with all major services affected." The strike has been called by the company JS: Prontexi.

For the PC being infected, you do not even click on links. Simply open a page with the ad harmful. The action uses a JavaScript code that initiates infection by exploiting various vulnerabilities s, including those related to the PDF.

According to Avast, the services most affected by this type of attack does not Yieldmanager.com (Yahoo) and fimserve.com (FOX Audience Network), which would account for more than 50% of cases. But they are also found to a lesser extent, cases via Doubleclick (Google), among others.

The code contained in the call server uses strong encryption and methods of camouflage, which makes the attack invisible to most antivirus (Avast, the company that made ​​the alert identifies, of course).

According to Avast, online advertising services should be more careful with the content they distribute.

In an interview with CNET, representatives from Yahoo and Google said they knew the problem and are taking action.

Source: http://idgnow.uol.com.br/seguranca/2010/03/23/yahoo-google-e-fox-disseminam-virus-em-anuncios/