Researchers claim to have found the world's largest and most lucrative mobile botnets.
Saxon Jiang, a researcher from North Carolina State University, found a botnet containing hundreds of thousands of infected nodes.
Symantec confirmed the botnet. Security response engineer Cathal Mullaney said the malware used to grow the bot was contained in almost 30 rogue applications on Chinese app stores.
The Android.Bmaster malware made premium-rate phone calls and text messages, and connect to pay-per-view videos.
Symantec researchers found the command-and-control server contacted hundreds of thousands of phones and generated $US10,000 ($A9372) per day and up to $3.5 million ($A2.9 million) annually.
"The botmaster has a fine-grained level of control over the infected devices," Mullaney wrote.
"Depending on which premium service [it] is attempting to contact, a number of configuration options are available to the botmaster."
He noted that the botnet is capable of additional malicious activity.
"Since this is a remote administration tool, the malware is capable of receiving commands from the remote server," Mullaney wrote.