"Unwanted ads or adware is popular category because after installation it does not request any further inputs, like banking trojans, and can simply generate revenue for developers right from the beginning," Threatpost quoted Stefanko.
"Also, it is not as difficult to create adware as it is to create Android ransomware or banking Trojans," Stefanko added.
The malicious category includes the applications that are infected by adware, subscription scams, hidden ads, SMS premium subscription, and more.
As per the report, most of the applications that were found to be malicious have been removed.
To recall, last month Google removed 46 apps from the marketplace belonging to Chinese mobile developer iHandy.