That finding comes via a mobile threats study released this week by Juniper Networks.
Overall, the study found, from March 2012 to March 2013 the volume of mobile malware increased 614% -- compared to the 155% increase seen in 2011 -- and comprised a total of 276,259 malicious apps. "This trend suggests that more attackers are shifting part of their efforts to mobile," according to the report.
[ What's the most dangerous Android malware out there? Read Android Trojan Looks, Acts Like Windows Malware. ]
How are devices getting infected? Third-party app markets are most often to blame. About 60% of these app markets are located in Russia, or in China, where access to Google Play is blocked. In total, Juniper counted over 500 third-party app stores hosting at least some mobile malware. "These third-party alternatives to official marketplaces often have low levels of accountability, allowing for malicious commodities to have a near infinite shelf life," said the report.
"These stores are also a concern for the several million 'jailbroken' iOS devices that rely on them to 'side load' apps," it said. That's one reason why mobile security experts recommend blocking any jailbroken iOS device from an enterprise network.
Regardless of the platform, every successful mobile malware infection, on average, earns an attacker money.