updated 11:33 pm EDT, Thu July 25, 2013
Flaw quickly exploited by hostile actors, more to come
Security researchers at Symantec have discovered the first utilizations of the "master key" Android vulnerability. At least six applications, distributed on Android marketplaces in China have been discovered with the exploit installed: two doctor's appointment schedulers, a news app, an arcade game, a card game, and a betting aide.
All six of these applications have been modified with added code to allow them to remotely control devices, steal IMEI and phone numbers off the infected device, send premium SMS messages, and disable a few Chinese mobile security software applications by using root commands.
Every Android contains a cryptographic signature to ensure to the kernel of the device that an app has not been tampered with. The vulnerability inserts code into an extant app without changing the signature of the app, in essence tricking Android into believing that an app is unchanged from initial installation.
Using this elevated access granted by manufacturer-specific apps, a Trojan-attacked app can then read any information on the device, recall all stored passwords, and "essentially take over the normal functioning of the phone and control any function thereof" including, but not limited to, phone calls, SMS messaging, camera use, and call recording.