After pushing malware, ad networks also used for DDoS

Hackers have figured out how to launch crippling distributed denial-of-service (DDoS) attacks through malicious advertisements

Rogue online advertisements that infect computers with malware have become a common occurrence on the Internet. But now, it appears, hackers have also figured out how to launch crippling distributed denial-of-service (DDoS) attacks through ad networks.

The DDoS mitigation team at CloudFlare recently observed a large-scale attack which they believe was the result of malicious ads being loaded inside apps and browsers on mobile devices.

The attack, which targeted one of the company's customers, peaked at 275,000 HTTP requests per second and was launched from over 650,000 unique IP (Internet Protocol) addresses, most of them from China.

What was interesting about this attack was that the requests appeared to be generated by real browsers, not scripts or malware, as are typically used in HTTP-based DDoS attacks. Furthermore, an analysis of the request headers indicated that almost 80 percent of the devices generating the traffic were smartphones and tablets.

The investigation revealed that the referrer for the requests was an attack page with multiple ads on it and embedded JavaScript code that loaded an additional script from other domains. That secondary script instructed the browsers to make Ajax (XHR) cross-origin calls in a loop to the victim site.

"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," said Marek Majkowski, a member of CloudFlare's DDoS mitigation team, in a blog post. "It seems probable that users were served advertisements containing the malicious JavaScript. These ads were likely showed in iframes in mobile apps, or mobile browsers to people casually browsing the internet."

Security researchers have warned about the possibility of mobile-based DDoS attacks for years, especially as mobile data connections become faster and more stable.

In a presentation at the Black Hat security conference in 2013, security researchers Jeremiah Grossman and Matt Johansen warned about the possibility of malicious advertisements being used to create a browser-based botnet that could be used to launch DDoS attacks, among other things. It appears that attackers might have finally caught up with that idea.

Malvertising attacks, which involve tricking ad networks into distributing advertisements that contain malicious code, have been used to infect computers with malware for years. Despite efforts from the networks to stop such incidents, attackers still seem to find a way in, most likely due to the complexity of the online advertising ecosystem.

A 2014 investigation by the U.S. Senate into malvertising concluded that online advertisements typically go through five or six intermediaries before they are delivered to users' browsers, and ads can be replaced with malicious ones at any point in that chain.

"The online advertising industry has grown in complexity to such an extent that each party can conceivably claim it is not responsible when malware is delivered to a user's computer through an advertisement," the Senate's Committee on Homeland Security and Governmental Affairs said in its report.

Join the newsletter!

Or

Sign up to gain exclusive access to email subscriptions, event invitations, competitions, giveaways, and much more.

Membership is free, and your security and privacy remain protected. View our privacy policy before signing up.

Error: Please check your email address.
Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Lucian Constantin

IDG News Service
Show Comments

Cool Tech

Toys for Boys

Family Friendly

Stocking Stuffer

SmartLens - Clip on Phone Camera Lens Set of 3

Learn more >

Christmas Gift Guide

Click for more ›

Brand Post

Most Popular Reviews

Latest Articles

Resources

PCW Evaluation Team

Aysha Strobbe

Microsoft Office 365/HP Spectre x360

Microsoft Office continues to make a student’s life that little bit easier by offering reliable, easy to use, time-saving functionality, while continuing to develop new features that further enhance what is already a formidable collection of applications

Michael Hargreaves

Microsoft Office 365/Dell XPS 15 2-in-1

I’d recommend a Dell XPS 15 2-in-1 and the new Windows 10 to anyone who needs to get serious work done (before you kick back on your couch with your favourite Netflix show.)

Maryellen Rose George

Brother PT-P750W

It’s useful for office tasks as well as pragmatic labelling of equipment and storage – just don’t get too excited and label everything in sight!

Cathy Giles

Brother MFC-L8900CDW

The Brother MFC-L8900CDW is an absolute stand out. I struggle to fault it.

Luke Hill

MSI GT75 TITAN

I need power and lots of it. As a Front End Web developer anything less just won’t cut it which is why the MSI GT75 is an outstanding laptop for me. It’s a sleek and futuristic looking, high quality, beast that has a touch of sci-fi flare about it.

Emily Tyson

MSI GE63 Raider

If you’re looking to invest in your next work horse laptop for work or home use, you can’t go wrong with the MSI GE63.

Featured Content

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?