Security Experts:

Google Fixes Privilege Escalation Vulnerabilities in Android 5.1 Lollipop

With the release of Android 5.1 Lollipop, Google has addressed two serious vulnerabilities that can be exploited for privilege escalation.

The flaws, which affect all Android versions prior to 5.1, were uncovered and reported by Guang Gong, a security researcher at the Chinese internet security company Qihoo 360.

One of the vulnerabilities (CVE-2015-1474) is an integer overflow that leads to heap corruption. The high-severity flaw, which has a CVSS base score of 10 (assigned in the NVD), allows a remote attacker to gain elevated privileges or cause a denial-of-service (DoS) condition on the targeted system.

“Multiple integer overflows in the GraphicBuffer::unflatten function in platform/frameworks/native/libs/ui/GraphicBuffer.cpp in Android through 5.0 allow attackers to gain privileges or cause a denial of service (memory corruption) via vectors that trigger a large number of file descriptors or integer values,” the researcher explained in an advisory published on Full Disclosure.

The second vulnerability (CVE-2015-1530) can also be exploited for privilege escalation or DoS. The flaw is caused by an integer overflow in the Android media package.

“An Integer overflow in the BnAudioPolicyService::onTransact function in frameworks/av/media/libmedia/IAudioPolicyService.cpp in Android through 5.0 allows attackers to gain privileges or cause a denial of service (memory corruption) via vectors that trigger a large number of count value,” reads the advisory for the bug.

“Simply put, these two vulnerabilities can be used to escalate privileges,” Gong told SecurityWeek via email. “In a real world scenario, when you install an app in Android, there are many restrictions to your app. But with these two vulnerabilities, your app can get more permissions than the system assigns to it.”

According to the researcher, malicious applications can exploit these vulnerabilities to surreptitiously carry out various tasks, including taking photos of the user and uploading them to a remote server, making phone calls, and sending messages.

Gong reported the vulnerabilities to Google in October and November 2014. In the case of CVE-2015-1474, the search giant had to release two patches because the first one was incomplete.

The researcher has made available POCs, details on the patches, and the vulnerable code.

Gong says he hasn’t received any reward from Google for his findings, but he is the first security researcher to be added to the Android Security Acknowledgements page in 2015.

Google rolled out Android 5.1 on Monday. The latest update introduces a new feature called Device Protection, which ensures that lost or stolen devices remain locked -- even if they are reset to factory settings -- until the owner signs in with their Google account.

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Eduard Kovacs (@EduardKovacs) is a contributing editor at SecurityWeek. He worked as a high school IT teacher for two years before starting a career in journalism as Softpedia’s security news reporter. Eduard holds a bachelor’s degree in industrial informatics and a master’s degree in computer techniques applied in electrical engineering.