New Ad Fraud Campaign Uses Millions of Domain Names to Bilk Advertising Networks

The digital advertising industry is getting socked with a new ad fraud campaign that's operating millions of fully qualified domain names (FQDN) and thousands of IPs to steal online ad revenue with shady ads and sham traffic-brokering.

In a report released today by digital threat management firm RiskIQ, researchers dug into the campaign run by a threat actor it calls NoTrove that demonstrates the lengths to which cybercriminals will go to steal from digital advertising networks - and the inherent weaknesses of the online ad ecosystem.

Unlike traditional malicious advertising, NoTrove isn't dropping malicious files on users' systems. Instead, it's making money by fraudulently redirecting clicks and in some cases downloading potentially unwanted programs (PUPs) that perpetuate more scam traffic so that NoTrove perpetrators can broker in sham advertising traffic.

"Traffic is critical to the giant exchanges in the online advertising space and to the very many niche affiliate network programs that exist, with organizations of all kinds tasked with monetizing and, ultimately, squeezing every last fraction of a penny of indirect marginal pro t of each URL visited," the report explains. "To monetize their traffic collecting, scammers like the one outlined in this report may participate in shady traffic affiliate programs or sell traffic to traffic brokers."

The researcher behind the report says the ubiquity of NoTrove is what sets the threat apart from other scammers and malware distributors taking advantage of vulnerable ad networks.

"NoTrove is literally everywhere," says William MacArthur, threat researcher for RiskIQ. "We’ve seen NoTrove burn through just under 2,000 domains and over 3,000 IPs. Combined with the 78 variations of campaign-specific middle word variants and randomized hostnames, we’ve seen NoTrove operate across millions of FQDNs."

Attackers go to extreme lengths like these because of the sheer amount of money at stake in online advertising fraud. According to eMarkter, digital ad spending is expected to hit $83 billion by the end of the year and $129 billion by 2021. It's a huge target of opportunity for fraudsters and has spawned a dizzying array of fraud campaigns like this one.

For example, last year researchers with ad fraud detection firm WhiteOps reported finding one of the largest ad fraud botnets ever, called MethBot, which it estimated was able to steal $3 million a day from programmatic video ad networks.

"Instead of the more traditional malware botnet structures, which involve attacks on existing IP addresses and piggybacking on residential computers, Methbot operators farm out their operations across a distributed network based on a custom browser engine running out of data centers on IP addresses acquired with forged registration data," WhiteOps explained in the report.

RiskIQ's MacArthur explains that NoTrove has been able to grow so large because it operates in a grey area of maliciousness that makes it possible for it to fly under the radar of many technologies that look for malicious advertising. With malvertising scams, the goal is to infect users with some sort of malware that can be used as a beach head for further attacks against each individual victims. Malwarebytes Labs researchers last week reported a new malvertising campaign called Binary Options that was delivering a Gozi banking Trojan payload through the RIG exploit kit in order to carry out a traditional malware assault against online users.

But with scams like NoTrove, the fraudsters are just trying to manipulate users' traffic in order to steal from digital advertising networks and publishers.

"This makes it different from normal malvertising as the content actually being delivered is not an injection leading to an exploit kit or a particular binary that people often track, so it’s a lot easier to operate compared to the more common Exploit Kit Threat operation," MacArthur says. "As a result, scammers are left unchecked and can balloon to outrageous sizes. Unfortunately for ad networks and publishers, the effect of scams and exploit kits can be the same: ad blocking by end users."

This is a big risk for the advertising industry--according to Jupiter Research, ad blocking will cost it $27 billion by the end of the decade. But MacArthurs says that security professionals from any industry can stand to observe NoTrove's tactics to keep apprised of evolving attack techniques.

"NoTrove is spread so far and wide that blocking one piece of its infrastructure is akin to playing whack-a-mole—no matter how many you hit, another will pop up. If left unchecked, NoTrove and threat actors like it will continue to balloon to even greater size, encompassing more domains, IPs, and other infrastructure," he says. "Threat actors of all kinds are taking a page from this playbook, accumulating massive swaths of infrastructure to carry out their campaigns and essentially overwhelm traditional security controls."

He recommends using machine learning and automation to identify subtle variances in payloads, and automatically blocking such nefarious infrastructure.

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