Google's DoubleClick advertising network is the lifeblood of many websites driven by ad revenue—and it's also a potential path of attack for criminals trying to spread extortionware and other malware. Some Huffington Post readers fell victim to malicious advertisements spread through Google's DoubleClick network early this week, but another simultaneous attack may have reached an even bigger audience. Two ad network merchants became an unwitting accomplice to attackers with similar Flash-based ads, displaying them on multiple legitimate sites.