Days after a critical vulnerability in the Stagefright multimedia playback engine broke headlines -- and maybe opened a new era in Android threats -- Trend Micro has gone public with another vulnerability affecting the way Android handles multimedia files. Researchers believe that the unpatched bug -- which Google has known about for over two months -- may become a popular in for mobile ransomware.
The vulnerability is in the Android mediaserver service used to index media files, and affects Android versions 4.3 (JellyBean) to 5.1.1 (Lollipop), which amounts to over half Android devices in use today.
According to researchers, it can "render a phone apparently dead -- silent, unable to make calls, with a lifeless screen."
Exploits may be delivered through either a specially crafted website or a malicious app. Mediaserver then cannot correctly process malformed video files, which causes the service to crash, "and with it, the rest of the operating system." If the screen was locked, it cannot be unlocked. If the malicious app is written to auto-start whenever the device boots up, it would cause the OS to crash again every time the device is turned on.
According to Trend Micro: "Whatever means is used to lure in users, the likely payload is the same. Ransomware is likely to use this vulnerability as a new 'threat' for users: in addition to ... the device being encrypted, the device itself would be locked out and unable to be used. This would increase the problems the user faces and make them more likely to pay any ransom."
Researchers reported the vulnerability to Google May 15; Google labeled it low-priority May 20 and has not yet provided a patch. No exploits have yet appeared in the wild.