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Stagefright 2.0 Vuln Affects Nearly All Android Devices

Worst threat is only to version 5.0 Lollipop and later

Once again, Android has been found slashed wide open to a critical vulnerability in its multimedia engine that is easy to exploit, enables remote privileged code execution, requires no user interaction, and affects nearly every Android device.

The so-called Stagefright 2.0 impacts over one billion Android devices, almost every one since version 1 was released in 2008 (although it's of greatest concern to version 5.0 Lollipop and later, which is only about 21 percent of Androids in use). 

Like its predecessor, Stagefright 2.0 was discovered by Zimperium Mobile Threat Protection, zLabs VP of Research Joshua J. Drake. Stagefright 2.0 is actually a set of two vulnerabilities in the way Android processes multimedia files. The first, CVE-2015-6602, is a vulnerability in libutils versions 1.0 and later. The second (which has not yet been assigned a CVE number) is in libstagefright versions 5.0 and later. The second bug triggers the first one, so Androids from version 5.0 and later are particularly at risk. In older devices, CVE-2015-6602 could be compromised by third-party apps or vendors/carrier functions that call libutils.

"The impact and severity of this pair of vulnerabilities is nearly identical to the original Stagefright issues," says Drake.

Stagefright 2.0 could be exploited via a malicious audio or video file. The bug is in how Android processes metadata, so the target doesn't need to actually open the audio or video file, but merely preview it. When Drake announced the original Stagefright at the end of July ahead of the Black Hat USA conference, the scariest attack vector proposed was via MMS message; because all an attacker would need is a phone number.

“At BlackHat USA 2015, Google announced that updated versions of Hangouts and Messenger were released to remove automatic processing of media received by MMS," Drake says. "However, nothing was done to prevent a user from interacting with media and Hangouts/Messenger remain a viable, though less attractive, attack vector.”

Drake says Stagefright 2.0's more likely to be exploited via browser-based attacks -- phishing messages, malvertising, man-in-the-middle attacks -- or via third-party apps that call to the vulnerable library.

The question with Stagefright 2.0, as with earlier core issues in Android, is how effective the Android ecosystem -- a sprawling patchwork of handset manufacturers, carriers, and third-party developers -- will be at delivering fixes. Zuk Avraham, founder, chairman and CTO at Zimperium, says that the Android ecosystem has "absolutely" changed its security behavior since the original Stagefright was revealed.

"Following the first Stagefright discovery and the announcement of Zimperium Handset Alliance (ZHA), device vendors and carriers united to offer shorter patch cycles for critical security incidents. We are excited to have made such an impact on the ecosystem," Avraham says.

"The advice I give friends and family is to buy handsets that allow for updates directly from the manufacturer," says Trey Ford, global security strategist at Rapid7. "For those who love Android -- buy directly from Google to remove the carrier-introduced delay when Android releases a security patch. For Google, this is an ecosystem problem. Google manages Android, and does a respectable job shipping patches. They deliver to the carriers, which in turns, the carriers take some time (picture 9-18 months) before those patches are certified and delivered over the air to the devices," Ford says. "In other cases, they don’t bother, as the handset life expectancy is so brief for the consumer. Discerning consumers are paying attention, they want to keep their patches up to date."

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