Google recently removed multiple applications from its Google Play store after reports surfaced linking the apps to adware.
Researchers at the security vendor Avast called out three apps laced with adware. The most popular of these is the Durak card game, which has been downloaded between five and 10 million times. The other apps were a history application and an IQ test app. Unlike other examples of adware, these applications waited an extended period of time before displaying anything.
“When you install Durak, it seems to be a completely normal and well working gaming app,” Avast’s Filip Chytry blogged Tuesday. “This was the same for the other apps, which included an IQ test and a history app. This impression remains until you reboot your device and wait for a couple of days. After a week, you might start to feel there is something wrong with your device. Some of the apps wait up to 30 days until they show their true colors. After 30 days, I guess not many people would know which app is causing abnormal behavior on their phone right?”
Each time an infected user unlocked their device an ad would be presented to them warning them about a problem such as the device being infected or out-of-date.
“This, of course, is a complete lie,” Chytry blogged.
The user is then asked to take action. If they approve, they are redirected to harmful threats on fake pages, such as “dubious app stores and apps that attempt to send premium SMS behind your back or to apps that simply collect too much of your data for comfort while offering you no additional value,” he continued.
Sometimes users were directed to security apps on Google Play. However even if the user installed the security apps, the ads would still appear, Chytry noted.
“This kind of threat can be considered good social engineering,” he wrote. “Most people won‘t be able to find the source of the problem and will face fake ads each time they unlock their device. I believe that most people will trust that there is a problem that can be solved with one of the apps advertised “solutions” and will follow the recommended steps, which may lead to an investment into unwanted apps from untrusted sources.”