Hackers are exploiting a weakness in Internet security, ad makers and sellers that target user’s online browsing habits.

Recently, Yahoo displayed and advertisement that contained malicious malware to European for at least one week. Additional high traffic websites have had malicious code injected into their display ads, newspapers, blogs and Dailymotion, a popular destination for streaming video.

In some instances, the malicious ads download viruses without user interaction. In other instances, the ads servers up a security alert- “Your computer’s antivirus is out of date!”- to trick you into paying a fraudsters money or downloading a virus. This type of spot ad is severed up unknowingly by major ad networks and can bypass antivirus software.

The design of the Internet advertising system is a major part of the problem. Ads pass through dozens of virtual hands to match buyers to sellers in quick online auctions. This process happens so fast with numerous players, that it can be very difficult to screen every ad, according to leading security researchers. Once a Hacker discovers a vulnerability others flock to use the same exploit, which is the case with the ad vulnerability.

In the Year 2013, cybersecurity company RiskIQ, Inc tracked nearly 384,000 malicious online ads. That up from 205,000 in 2012 and 70,000 in 2011. The large ad companies acknowledge an increase in malicious  ads.

Google, which hosts one of the largest ad networks has disabled ads from than 400,000 sites containing malware in 2013, up from 123,000 in 2012.

Advertisers have known about the potential problems of malware for years, but have struggled to eliminate the threat. Scanning the web ad for bugs is time-consuming, expensive and is difficult to do as more ads are becoming interactive with graphics and complex code to target a specific type of user. “This is much like an arms race” stated Chris Olson, chief executive of Media Trust, an ad-security company in McLean, VA.

In Yahoo’s case, the malicious ad was on display between December 27th and January 3rd before it was discovered. It is impossible to find out how many people were infected because the virus only was deployed in certain instances, according to people who are familiar with the investigation. If the malicious ad discovered a vulnerability, it infected the machine with a host of viruses. One of them is called Zeus, it is often used to steal online banking credentials, according to security researches who have studied the incident.

This is why you need a good firewall to help you prevent this type of attack. I have recommended blocking Ad sites for at least two years because they contain a vulnerability. The companies who have listened to me, have cut down their malware infections significantly.

If you don’t have the ability to block ads at the firewall, contact me and I can get help you find a suitable security device or help make recommendations. Just call 262-373-9070 or email james@tbjconsulting.com