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1.4 Billion Androids Open To Spying Via New TCP Flaw

Flaw first described by researchers to affect web servers also leaves mobile devices exposed.

A serious vulnerability disclosed last week in the Transmission Control Protocol (TCP) used by Linux that put a slew of servers and high-profile websites at risk has now been found to put the vast majority of the Android ecosystem in danger as well.

According to new findings from the researchers at Lookout, the flaw leaves 1.4 billion Android devices exposed -- some 80% of the platform's installed base.

Discovered by a team of researchers from University of California, Riverside, and the US Army Research Laboratory, the vulnerability (CVE-2016-5696) was presented last week at the USENIX Security Symposium. The flaw allows for a side-channel attack that can be used to predict TCP sequence numbers, which then can allow attackers to degrade traffic encryption and perform website hijacking and blind data injection.

"The flaw manifests as a side channel that affects all Linux kernel versions 3.6 and beyond and may possibly be replicated in other operating systems if left unnoticed," the researchers wrote in their symposium paper.

According to Craig Young, security researcher with Tripwire's vulnerability and exposures research team, this is a pretty serious problem. 

"This can allow attackers to launch the TCP hijacking attacks, which were so prominent in the 1990s hacking scene," Young says. "Back then the problem was that many computers would generate initial sequence values from the clock, thereby greatly reducing the number of guesses needed to take control of a remote session. Kevin Mitnick is known for use of this type of attack.”

The latest development from Lookout shows that the initial researchers were right about there being potential cascading ramifications from this flaw. The vulnerability was patched in the Linux kernel well before the USENIX symposium talk, but according to Lookout, Android versions still remain vulnerable likely because the patched Linux kernel wasn't available before the latest Android update.

As a result, pretty much all Android versions running Android 4.4 KitKat or later are exposed to attacks against this vulnerability.

"If you’re running an enterprise mobility program, a number of Android devices are potentially vulnerable to a serious spying attack," writes Andrew Blaich of Lookout. "CISOs should be aware that this new vulnerability affects their Linux environments, Linux-based server connections in addition to Android devices. Enterprises are encouraged to check if any of the traffic to their services (such as email) is using unencrypted communications."

Until the Linux kernel is updated on Android devices, enterprises can take extra precautions by making sure that the websites users browse and the apps they use are employ HTTPS with TLS. A VPN also is recommended as an extra layer of defense. 

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