New Type of DDoS Attack Uses Mobile Ad Networks

A new type of distributed denial of service attack has recently been reported by CloudFlare, involving the use of mobile advertisement networks and funneling traffic from real users.

Although the reported attack only lasted a couple of hours, the company reported more than 275,000 HTTP requests per second, peaking at 4.5 billion requests during a single day against a targeted domain. According to investigations conducted by the company, legitimate users browsing the web were served ads via an iframe which requested the ad’s content from the server of the attacker.

In this case, the ad network was used to deliver a malicious ad containing a piece of JavaScript code that launched an Ajax request aimed at a targeted website, by leveraging legitimate traffic coming from unsuspecting victims.

Further investigation into the attack logs has revealed not only that 99.8 percent, of the attack originated from China, but also that 80 percent of requests came from mobile devices. Analyzing the user agent from all collected logs revealed that 72 percent of the flooding traffic originated from mobile devices, 23 percent originated from desktops, and 5 percent from tables.

“There is no way to know for sure why so many mobile devices visited the attack page, but the most plausible distribution vector seems to be an ad network,” wrote Marek Majkowski. “It seems probable that users were served advertisements containing the malicious JavaScript. This ads were likely showed in iframes in mobile apps, or mobile browsers to people casually browsing the internet.”