Google has remotely purged Android smartphones of applications tainted with a malicious code that could take control of the handsets and steal information.
Mobile phone security firm LookOut said the purpose of the "DroidDream" code was to "download additional applications and install them silently as system applications on the device.
"DroidDream could be considered a powerful zombie agent that can install any applications silently and execute code with root privileges at will," it said.
Google was patching the vulnerability that cyber crooks could exploit and adding measures to prevent applications containing the "malware" from getting into the Android Market of programs for mobile devices.
Google yanked the contaminated applications from the Android Market and then took the unusual step of hitting a "kill switch" that remotely removed from smartphones any of the more than 50 applications containing the dangerous code.
"We removed the malicious applications from Android Market, suspended the associated developer accounts, and contacted law enforcement about the attack," Rich Cannings of Android Security said in a message posted at the Google blog during the weekend.
"We are remotely removing the malicious applications from affected devices."
Google believed that hackers were only able to get codes identifying smartphones and which version of Android ran particular devices. The attack didn't work on handsets operating on Android 2.2.2 or newer.
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