Google has yanked more than two-dozen mobile apps from its Android Market after security researchers reported they were laced with malicious code that transferred user data to servers controlled by attackers.
As many as 120,000 Android users downloaded the trojans before they were detected, according to Tim Wyatt, a researcher with mobile security firm Lookout. Once installed, the apps secretly siphoned the IMEI (or international mobile equipment identity), IMSI (or International Mobile Subscriber Identifier), handset model, and details about other apps and software installed on the infected handsets.
The apps also contained code that was triggered when users received text messages, according to an analysis from antivirus provider F-Secure.
“The added code will connect to a server and send details about the infected handset to the malware authors,” F-Secure Chief Research Officer Mikko Hypponen wrote. “So we're talking about a mobile botnet.”
It's at least the second rash of malicious apps discovered in the official Android Market in as many months. In late March, Lookout researchers discovered a separate outbreak of 50 malicious apps that they dubbed “DroidDream.” In both cases, the attackers downloaded legitimate programs from the Google bazaar, added malicious code to them, and then made the modified versions available in the same forum.
Lookout identified 26 apps in the most recent outbreak. Infected programs carried titles such as Hot Girls 1, Floating Image Free, System Monitor, Quick Photo Grid, and Quick SMS Backup. Based on information included with the apps, the number of affected users numbered from 30,000 to 120,000.
Google has so far taken a laissez-faire approach to policing the Android Market, relying on users and security researchers to identify malicious apps. Company representatives have counseled users to pay close attention to disclosures that are shown when apps get installed to make sure they are legitimate. The company has stopped short of vetting the apps itself to check for security threats.
A Google spokesman didn't immediately reply to an email seeking comment for this article.
Two weeks ago, Google plugged a security hole that exposed the vast majority of Android phone users' calendars and contacts when they accessed those services over unsecured networks. ®