CVE-2014-9888 in Android
Summary
by MITRE
arch/arm/mm/dma-mapping.c in the Linux kernel before 3.13 on ARM platforms, as used in Android before 2016-08-05 on Nexus 5 and 7 (2013) devices, does not prevent executable DMA mappings, which might allow local users to gain privileges via a crafted application, aka Android internal bug 28803642 and Qualcomm internal bug CR642735.
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Analysis
by VulDB Data Team • 09/12/2022
The vulnerability described in CVE-2014-9888 represents a critical security flaw in the Linux kernel's memory management subsystem specifically affecting ARM-based platforms. This issue resides within the dma-mapping.c file in kernel versions prior to 3.13, making it particularly concerning for Android devices that were prevalent in 2014, including Nexus 5 and 7 (2013) models. The vulnerability stems from insufficient protection mechanisms that fail to prevent the creation of executable DMA mappings, which creates a fundamental security gap in the kernel's memory management architecture. The flaw allows for privilege escalation through crafted applications, making it a significant concern for mobile device security where users may unknowingly execute malicious code that exploits this kernel-level vulnerability.
The technical root cause of this vulnerability lies in the improper handling of DMA (Direct Memory Access) mappings within the ARM kernel implementation. DMA mappings are used to allow hardware devices to access system memory directly without CPU intervention, which is essential for performance in embedded systems and mobile devices. However, the kernel's failure to enforce proper memory protection flags means that DMA mappings can be created with execute permissions, effectively bypassing the kernel's memory protection mechanisms. This allows malicious applications to create memory regions that can simultaneously serve as both data storage and executable code storage, violating fundamental security principles that separate data and code execution. The vulnerability specifically affects the ARM architecture's memory management unit (MMU) implementation where the kernel fails to properly validate or restrict the permissions associated with DMA-mapped memory regions, creating a pathway for code execution in kernel space.
The operational impact of this vulnerability extends beyond simple privilege escalation to represent a complete breakdown in the kernel's memory protection model. Local users can exploit this flaw to execute arbitrary code with kernel-level privileges, effectively bypassing all standard security mechanisms including SELinux, app sandboxing, and other Android security controls. This vulnerability is particularly dangerous in mobile environments where users may unknowingly install malicious applications that can leverage this kernel flaw to gain root access to the device. The exploitation scenario involves a crafted application that can manipulate DMA mapping operations to create executable memory regions, which then allows the malicious code to execute with the highest possible privileges. This type of vulnerability can lead to complete device compromise, data theft, and persistent backdoor access, making it a severe threat to both individual privacy and device security.
Mitigation strategies for CVE-2014-9888 primarily focus on kernel version updates and architectural security improvements. The most effective solution is upgrading to Linux kernel version 3.13 or later, which includes proper protections against executable DMA mappings. Device manufacturers and Android OS maintainers should prioritize rolling out security patches to affected devices, particularly those running older kernel versions. The vulnerability aligns with CWE-787 (Out-of-bounds Write) and CWE-788 (Out-of-bounds Read) categories, representing memory safety issues that can lead to privilege escalation. From an ATT&CK framework perspective, this vulnerability maps to T1068 (Exploitation for Privilege Escalation) and T1059 (Command and Scripting Interpreter), as it enables attackers to execute code with elevated privileges. Additional mitigations include implementing proper kernel memory protection mechanisms, enforcing stricter DMA mapping validation, and deploying kernel lockdown features that prevent the creation of executable memory regions. Organizations should also consider implementing runtime memory protection mechanisms and monitoring for suspicious DMA mapping activities that could indicate exploitation attempts.