CVE-2014-9870 in Android
Summary
by MITRE
The Linux kernel before 3.11 on ARM platforms, as used in Android before 2016-08-05 on Nexus 5 and 7 (2013) devices, does not properly consider user-space access to the TPIDRURW register, which allows local users to gain privileges via a crafted application, aka Android internal bug 28749743 and Qualcomm internal bug CR561044.
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Analysis
by VulDB Data Team • 09/12/2022
The vulnerability described in CVE-2014-9870 represents a critical privilege escalation flaw within the Linux kernel's ARM architecture implementation that affected Android devices prior to August 2016. This issue stems from improper handling of user-space access to the TPIDRURW register, a specialized control register designed for thread-local storage management in ARM processors. The flaw exists specifically in kernel versions before 3.11 and impacts devices including the Nexus 5 and Nexus 7 (2013) models, making it particularly significant for mobile security assessments and Android vulnerability management.
The technical implementation of this vulnerability involves the TPIDRURW register, which is intended to provide user-space applications with read and write access to thread-local storage information while maintaining proper kernel-level protection boundaries. However, the kernel's implementation fails to properly validate or restrict user-space access to this register, creating a pathway for privilege escalation. Attackers can craft malicious applications that manipulate the register contents to bypass kernel security mechanisms, effectively elevating their privileges from user-level to kernel-level execution. This register-based privilege escalation technique aligns with CWE-264, which covers permissions, privileges, and access control weaknesses, and demonstrates how improper register management can undermine fundamental security boundaries.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to execute arbitrary code with kernel-level privileges, potentially compromising the entire device. Mobile device security is particularly vulnerable to such flaws since Android applications run in sandboxed environments that rely on kernel-level protections to maintain system integrity. The vulnerability's presence in widely deployed Nexus devices meant that a significant number of Android users were exposed to potential exploitation, with the attack surface extending to any application that could leverage this register access flaw. This represents a classic case of a kernel-level vulnerability that can be exploited through user-space applications, as categorized under ATT&CK technique T1068 for privilege escalation.
Mitigation strategies for this vulnerability require immediate kernel updates to version 3.11 or later, which properly implement register access controls and prevent unauthorized user-space manipulation of the TPIDRURW register. Device manufacturers should prioritize security patches for affected Android versions, particularly for Nexus devices that received extended support periods. System administrators and security teams should implement monitoring for suspicious register access patterns and consider applying kernel hardening patches that restrict access to sensitive control registers. The vulnerability demonstrates the importance of proper kernel register management and access control implementation, with implications for both mobile and embedded system security. Organizations should conduct comprehensive vulnerability assessments to identify devices running vulnerable kernel versions and ensure timely patch deployment to protect against potential exploitation.