AUSTIN, TX: Ad fraud appears on over half of uncertified apps and in nearly one tenth of certified app traffic, according to a new study.

Sizmek, an open ad-management company, analysed around 20bn app impressions on iOS and Android devices and found that 24,000 apps not certified by official stores were generating malicious traffic; there were also instances of malicious traffic in around 4,000 certified apps.

The study, Advertising Fraud in Mobile Apps, reported a "staggering volume" of malicious traffic, which manifested as unsolicited or non-viewable advertising.

For iOS devices, half (50%) of illegally downloaded uncertified apps performed malicious activity, while this was true of more than half (56%) of all uncertified apps on Android devices.

Such apps are generally downloaded from third-party app stores or websites, where malicious developers place sophisticated and often legitimate-looking apps.

"Uncertified apps have become a breeding ground for fraud, so brands need to be vigilant with their mobile targeting as well as their blacklists when seeking safe options to reach and impact audiences via mobile," said Zach Schapira, Global Product Strategist at Sizmek.

The problem for advertisers, however, is that "fraud is becoming less obvious and harder to detect", according to Augustine Fou, an independent ad fraud researcher, who told Ad Exchanger that this was especially true of mobile.

"Put simply, none of the Javascript-based fraud-detection tech can measure mobile (apps specifically); those require measurement SDKs," he explained. "But obviously the bad guys don't install fraud-detection SDKs in their mobile apps."

More generally, Advertising Age noted that as spending in mobile increases, fraudsters are likely to focus attention here, using tactics such as toolbar click injection, malvertising and increasingly sophisticated bots to simulate human activity.

It also expected that 2017 would see a resurgence of attribution fraud as adtech and martech converge; "without a method to track and eliminate sophisticated fraud across their ad buys, advertisers have much to lose," it said.

Data sourced from Sizmek, Ad Exchanger, Advertising Age; additional content by Warc staff