Researchers at mobile security firm TrustGo said they have uncovered a piece of Android malware in multiple app stores that has spread to more than 100,000 devices. It's yet another example of malware challenges facing Googles mobile operating system.
The MMarketPay.A Trojan is being hidden in several seemingly legitimate applications, including travel and weather apps. So far, the Trojan has been seen in nine different Chinese app stores, according to the company.
The malware downloads paid applications and content from China Mobile's Mobile Market (M-Market). Normally, TrustGo's Security Labs explained in a blog post, customers have to log into M-Market (http://mm.10086.cn) to buy apps. M-Market will send a verification code to the customer through SMS to ensure a particular purchase was valid. Once the customers input the code into M-Market for verification, the market will download the application.
This malware, however, circumvents this process and places orders for applications automatically, potentially causing users to be hit with unexpectedly high phone bills, TrustGo noted. This includes intercepting the verification code sent by text message and posting the code to the M-Market site to complete the transaction. If a CAPTCHA is used, the malware will send the image to a remote server for review, according to TrustGo's analysis.
Mobile malware has increasingly become a challenge on the Android platform, with attackers looking to take advantage of Google's more open approach to developers. In response, Google revealed earlier this year that it had instituted a protection mechanism for its app store known as Bouncer. However, even Bouncer itself has become a target, and researchers plan to disclose some of the ways it can be bypassed at the upcoming Black Hat USA conference in Las Vegas.
While third-party app stores and other smaller Websites have been caught pushing malicious applications for a while now, they dont have the same number of users as larger, well-known marketplaces, said Vikram Thakur, principal security response manager at Symantec. As a result, that lends itself to a larger number of unique malicious apps and a smaller number of infections.
Regardless, there have been many instances of Android malware infections have been traced to third-party stores as opposed to Google Play. In April, for example, researchers at NQ Mobile and North Carolina State University discovered Android malware that could be used to record calls and surrounding noise.
Thakur suggested a number of ways users can protect themselves and their devices. Besides using mobile antivirus technology, users should only use third-party app marketplaces hosted by well-known, legitimate vendors for downloading and installing apps, he said. In addition, users should always review other users' comments on the application they are looking to download.
"Next, users should pay attention to the name of the app creator," Thakur wrote in an email. "If downloading a popular app from a well-known app creator, an app that purports to be the legitimate version, but has a different author listed should be a definite red flag. Fourth, during the installation of apps, users should always check the access permissions being requested for installation; if they seem excessive for what the application is designed to do, it would be wise to not install the application."