Nexus Security Bulletin—January 2016

In this document

Published January 04, 2016 | Updated April 28, 2016

We have released a security update to Nexus devices through an over-the-air (OTA) update as part of our Android Security Bulletin Monthly Release process. The Nexus firmware images have also been released to the Google Developer site. Builds LMY49F or later and Android 6.0 with Security Patch Level of January 1, 2016 or later address these issues. Refer to the Common Questions and Answers section for more details.

Partners were notified about and provided updates for the issues described in this bulletin on December 7, 2015 or earlier. Where applicable, source code patches for these issues have been released to the Android Open Source Project (AOSP) repository.

The most severe of these issues is a Critical security vulnerability that could enable remote code execution on an affected device through multiple methods such as email, web browsing, and MMS when processing media files.

We have had no reports of active customer exploitation of these newly reported issues. Refer to the Mitigations section for details on the Android security platform protections and service protections such as SafetyNet, which improve the security of the Android platform. We encourage all customers to accept these updates to their devices.

Security Vulnerability Summary

The table below contains a list of security vulnerabilities, the Common Vulnerability and Exposures ID (CVE), and their assessed severity. The severity assessment is based on the effect that exploiting the vulnerability would have on an affected device, assuming the platform and service mitigations are disabled for development purposes or if successfully bypassed.

Issue CVE Severity
Remote Code Execution Vulnerability in Mediaserver CVE-2015-6636 Critical
Elevation of Privilege Vulnerability in misc-sd driver CVE-2015-6637 Critical
Elevation of Privilege Vulnerability in the Imagination Technologies driver CVE-2015-6638 Critical
Elevation of Privilege Vulnerabilities in Trustzone CVE-2015-6639
CVE-2015-6647
Critical
Elevation of Privilege Vulnerability in Kernel CVE-2015-6640 Critical
Elevation of Privilege Vulnerability in Bluetooth CVE-2015-6641 High
Information Disclosure Vulnerability in Kernel CVE-2015-6642 High
Elevation of Privilege Vulnerability in Setup Wizard CVE-2015-6643 Moderate
Elevation of Privilege Vulnerability in Wi-Fi CVE-2015-5310 Moderate
Information Disclosure Vulnerability in Bouncy Castle CVE-2015-6644 Moderate
Denial of Service Vulnerability in SyncManager CVE-2015-6645 Moderate
Attack Surface Reduction for Nexus Kernels CVE-2015-6646 Moderate

Mitigations

This is a summary of the mitigations provided by the Android security platform and service protections such as SafetyNet. These capabilities reduce the likelihood that security vulnerabilities could be successfully exploited on Android.

  • Exploitation for many issues on Android is made more difficult by enhancements in newer versions of the Android platform. We encourage all users to update to the latest version of Android where possible.
  • The Android Security team is actively monitoring for abuse with Verify Apps and SafetyNet which will warn about potentially harmful applications about to be installed. Device rooting tools are prohibited within Google Play. To protect users who install applications from outside of Google Play, Verify Apps is enabled by default and will warn users about known rooting applications. Verify Apps attempts to identify and block installation of known malicious applications that exploit a privilege escalation vulnerability. If such an application has already been installed, Verify Apps will notify the user and attempt to remove any such applications.
  • As appropriate, Google Hangouts and Messenger applications do not automatically pass media to processes such as mediaserver.

Acknowledgements

We would like to thank these researchers for their contributions:

  • Abhishek Arya, Oliver Chang, and Martin Barbella of Google Chrome Security Team: CVE-2015-6636
  • Sen Nie (@nforest_) and jfang of KEEN lab, Tencent (@K33nTeam): CVE-2015-6637
  • Yabin Cui from Android Bionic Team: CVE-2015-6640
  • Tom Craig of Google X: CVE-2015-6641
  • Jann Horn (https://thejh.net): CVE-2015-6642
  • Jouni Malinen PGP id EFC895FA: CVE-2015-5310
  • Quan Nguyen of Google Information Security Engineer Team: CVE-2015-6644
  • Gal Beniamini (@laginimaineb, http://bits-please.blogspot.com): CVE-2015-6639

Security Vulnerability Details

In the sections below, we provide details for each of the security vulnerabilities listed in the Security Vulnerability Summary above. There is a description of the issue, a severity rationale, and a table with the CVE, associated bug, severity, updated versions, and date reported. When available, we will link the AOSP change that addressed the issue to the bug ID. When multiple changes relate to a single bug, additional AOSP references are linked to numbers following the bug ID.

Remote Code Execution Vulnerability in Mediaserver

During media file and data processing of a specially crafted file, vulnerabilities in mediaserver could allow an attacker to cause memory corruption and remote code execution as the mediaserver process.

The affected functionality is provided as a core part of the operating system and there are multiple applications that allow it to be reached with remote content, most notably MMS and browser playback of media.

This issue is rated as a Critical severity due to the possibility of remote code execution within the context of the mediaserver service. The mediaserver service has access to audio and video streams as well as access to privileges that third-party apps cannot normally access.

CVE Bug(s) with AOSP links Severity Updated versions Date reported
CVE-2015-6636 ANDROID-25070493 Critical 5.0, 5.1.1, 6.0, 6.0.1 Google Internal
ANDROID-24686670 Critical 5.0, 5.1.1, 6.0, 6.0.1 Google Internal

Elevation of Privilege Vulnerability in misc-sd driver

An elevation of privilege vulnerability in the misc-sd driver from MediaTek could enable a local malicious application to execute arbitrary code within the kernel. This issue is rated as a Critical severity due to the possibility of a local permanent device compromise, in which case the device would possibly need to be repaired by re-flashing the operating system.

CVE Bug(s) Severity Updated versions Date reported
CVE-2015-6637 ANDROID-25307013* Critical 4.4.4, 5.0, 5.1.1, 6.0, 6.0.1 Oct 26, 2015

* The patch for this issue is not in AOSP. The update is contained in the latest binary drivers for Nexus devices available from the Google Developer site.

Elevation of Privilege Vulnerability in the Imagination Technologies driver

An elevation of privilege vulnerability in a kernel driver from Imagination Technologies could enable a local malicious application to execute arbitrary code within the kernel. This issue is rated as a Critical severity due to the possibility of a local permanent device compromise, in which case device would possibly need to be repaired by re-flashing the operating system.

CVE Bug(s) Severity Updated versions Date reported
CVE-2015-6638 ANDROID-24673908* Critical 5.0, 5.1.1, 6.0, 6.0.1 Google Internal

* The patch for this issue is not in AOSP. The update is contained in the latest binary drivers for Nexus devices available from the Google Developer site.

Elevation of Privilege Vulnerabilities in Trustzone

Elevation of privilege vulnerabilities in the Widevine QSEE TrustZone application could enable a compromise, privileged application with access to QSEECOM to execute arbitrary code in the Trustzone context. This issue is rated as a Critical severity due to the possibility of a local permanent device compromise, in which case the device would possibly need to be repaired by re-flashing the operating system.

CVE Bug(s) Severity Updated versions Date reported
CVE-2015-6639 ANDROID-24446875* Critical 5.0, 5.1.1, 6.0, 6.0.1 Sep 23, 2015
CVE-2015-6647 ANDROID-24441554* Critical 5.0, 5.1.1, 6.0, 6.0.1 Sep 27, 2015

* The patch for this issue is not in AOSP. The update is contained in the latest binary drivers for Nexus devices available from the Google Developer site.

Elevation of Privilege Vulnerability in Kernel

An elevation of privilege vulnerability in the kernel could enable a local malicious application to execute arbitrary code in the kernel. This issue is rated as a Critical severity due to the possibility of a local permanent device compromise, in which case the device would possibly need to be repaired by re-flashing the operating system.

CVE Bug(s) with AOSP Link Severity Updated versions Date reported
CVE-2015-6640 ANDROID-20017123 Critical 4.4.4, 5.0, 5.1.1, 6.0 Google Internal

Elevation of Privilege Vulnerability in Bluetooth

An elevation of privilege vulnerability in the Bluetooth component could enable a remote device paired over Bluetooth to gain access to user’s private information (Contacts). This issue is rated as High severity because it could be used to gain “dangerous” capabilities remotely, these permissions are accessible only to third-party applications installed locally.

CVE Bug(s) with AOSP links Severity Updated versions Date reported
CVE-2015-6641 ANDROID-23607427 [2] High 6.0, 6.0.1 Google Internal

Information Disclosure Vulnerability in Kernel

An information disclosure vulnerability in the kernel could permit a bypass of security measures in place to increase the difficulty of attackers exploiting the platform. These issues are rated as High severity because they could also be used to gain elevated capabilities, such as Signature or SignatureOrSystem permissions privileges, which are not accessible to third-party applications.

CVE Bug(s) Severity Updated versions Date reported
CVE-2015-6642 ANDROID-24157888* High 4.4.4, 5.0, 5.1.1, 6.0 Sep 12, 2015

* The patch for this issue is not in AOSP. The update is contained in the latest binary drivers for Nexus devices available from the Google Developer site.

Elevation of Privilege Vulnerability in Setup Wizard

An elevation of privilege vulnerability in the Setup Wizard could enable an attacker with physical access to the device to gain access to device settings and perform a manual device reset. This issue is rated as Moderate severity because it could be used to improperly work around the factory reset protection.

CVE Bug(s) with AOSP links Severity Updated versions Date reported
CVE-2015-6643 ANDROID-25290269 [2] Moderate 5.1.1, 6.0, 6.0.1 Google Internal

Elevation of Privilege Vulnerability in Wi-Fi

An elevation of privilege vulnerability in the Wi-Fi component could enable a locally proximate attacker to gain access to Wi-Fi service related information. A device is only vulnerable to this issue while in local proximity. This issue is rated as Moderate severity because it could be used to gain “normal” capabilities remotely, these permissions are accessible only to third-party applications installed locally.

CVE Bug(s) with AOSP links Severity Updated versions Date reported
CVE-2015-5310 ANDROID-25266660 Moderate 4.4.4, 5.0, 5.1.1, 6.0, 6.0.1 Oct 25, 2015

Information Disclosure Vulnerability in Bouncy Castle

An information disclosure vulnerability in Bouncy Castle could enable a local malicious application to gain access to user’s private information. This issue is rated as Moderate severity because it could be used to improperly gain “dangerous” permissions.

CVE Bug(s) with AOSP links Severity Updated versions Date reported
CVE-2015-6644 ANDROID-24106146 Moderate 4.4.4, 5.0, 5.1.1, 6.0, 6.0.1 Google Internal

Denial of Service Vulnerability in SyncManager

A denial of service vulnerability in the SyncManager could enable a local malicious application to cause a reboot loop. This issue is rated as Moderate severity because it could be used to cause a local temporary denial of service that would possibly need to be fixed though a factory reset.

CVE Bug(s) with AOSP links Severity Updated versions Date reported
CVE-2015-6645 ANDROID-23591205 Moderate 4.4.4, 5.0, 5.1.1, 6.0 Google Internal

Attack Surface Reduction for Nexus Kernels

SysV IPC is not supported in any Android Kernel. We have removed this from the OS as it exposes additional attack surface that doesn’t add functionality to the system that could be exploited by malicious applications. Also, System V IPCs are not compliant with Android's application lifecycle because the allocated resources are not freeable by the memory manager leading to global kernel resource leakage. This change addresses issue such as CVE-2015-7613.

CVE Bug(s) Severity Updated versions Date reported
CVE-2015-6646 ANDROID-22300191* Moderate 6.0 Google Internal

* The patch for this issue is not in AOSP. The update is contained in the latest binary drivers for Nexus devices available from the Google Developer site.

Common Questions and Answers

This section reviews answers to common questions that may occur after reading this bulletin.

1. How do I determine if my device is updated to address these issues?

Builds LMY49F or later and Android 6.0 with Security Patch Level of January 1, 2016 or later address these issues. Refer to the Nexus documentation for instructions on how to check the security patch level. Device manufacturers that include these updates should set the patch string level to: [ro.build.version.security_patch]:[2016-01-01]

Revisions

  • January 04, 2016: Bulletin published.
  • January 06, 2016: Bulletin revised to include AOSP links.
  • April 28, 2016: Removed CVE-2015-6617 from Acknowledgements and added CVE-2015-6647 to summary table