The number of mobile apps infected with malware or that are conduits for spyware in Google's Play Store nearly quadrupled between 2011 and 2013, a security vendor has reported.
In 2011, there were about 11,000 apps in Google's mobile marketplace that contained malicious software capable of stealing people's data and committing fraud, according to the results of a study published Wednesday by RiskIQ, an online security services company. By 2013, more than 42,000 apps in Google's store contained spyware and information-stealing Trojan programs, the company said. (RiskIQ did not analyze apps in Apple's App Store.)
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RiskIQ CEO Elias Manousos told InfoWorld that its definition of spyware includes apps that connect to advertising networks, a group that comprises about half the reported "malicious" apps. Many apps use ad networks legitimately, but some ad networks are used essentially as money-laundering mechanisms for data obtained through deceptive practices within apps, as well as through spyware apps. Developers may not be aware that their apps use such "gray market" ad networks or have components obtained from other developers that are actually spyware. Legitimate ad networks can also be conduits for such "gray market" apps. Manousos said its count of suspect apps that used ad networks included only apps that antivirus vendors or other investigations separately identified as problematic, so the count does not include all apps that use ad networks.
Although RiskIQ's analysis only covers Android apps, iOS and other platforms' apps are equally vulnerable to this sort of ad network abuse because in many cases it is the network or a back-end service that is compromised.
Apps designed to personalize people's Android smartphones were most susceptible, as well as entertainment and gaming apps. Some of the most malicious apps in the Google Play store downloaded since 2011 were Wallpaper Dragon Ball, a wallpaper app, and the games Finger Hockey and Subway Surfers Free Tips.
Both Wallpaper Dragon Ball and Finger Hockey, RiskIQ said, have malware that steals confidential information such as device IDs from infected devices. Subway Surfers Free Tips, meanwhile, uses a Trojan called Air Push to bypass a device's security settings and subscribe infected phones to premium services, the company said.
RiskIQ performed its analysis using its own software that crawls app stores, websites, and Web ads. The technology, the company said, exposes malware that would otherwise not show itself to traditional Web crawler software.
Android apps were only counted as being malicious if they behaved in specific ways as a result of malware. The behavior may include collecting and sending GPS coordinates, contact lists and email addresses to third parties; recording phone conversations and sending them to attackers; taking control of the infected phone; or downloading other malware onto the phone.
The findings show that the rising prominence of mobile apps among consumers also makes them a juicy target for hackers. Reports of possible malware in clones of the popular Flappy Bird mobile game recently surfaced, even after it was removed from app stores.
"The explosive growth of mobile apps has attracted a criminal element looking for new ways to distribute malware that can be used to commit fraud, [commit] identity theft, and steal confidential data," said Manousos, in announcing the findings. Malicious apps are an effective way to infect users, he said, since they often exploit the trust people have in brands and companies they do business with.
But while the number of malicious Android apps is rising, the percentage of them removed by Google is on the decline, researchers said. In 2011 Google removed 60 percent of malicious apps, but in 2013 the company removed less than a quarter of them, the report said. That's probably due to the rapid increase in malicious software. Manousos told InfoWorld that he theorizes that Google takes down apps only after it has received enought complaints or alerts from security researchers, creating a delay in its takedowns to the 2013 surge. Unlike Apple, Google does not vet apps rigorously before they are made available in its app store, he noted.
Google said it would need more information about RiskIQ's analysis to comment on the findings.
Zach Miners covers social networking, search and general technology news for IDG News Service. Follow Zach on Twitter at @zachminers. Zach's e-mail address is firstname.lastname@example.org. InfoWorld executive editor Galen Gruman contributed to this report.