CVE-2013-4739 in Android-msm
Summary
by MITRE
The MSM camera driver for the Linux kernel 3.x, as used in Qualcomm Innovation Center (QuIC) Android contributions for MSM devices and other products, allows attackers to obtain sensitive information from kernel stack memory via (1) a crafted MSM_MCR_IOCTL_EVT_GET ioctl call, related to drivers/media/platform/msm/camera_v1/mercury/msm_mercury_sync.c, or (2) a crafted MSM_JPEG_IOCTL_EVT_GET ioctl call, related to drivers/media/platform/msm/camera_v2/jpeg_10/msm_jpeg_sync.c.
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Analysis
by VulDB Data Team • 03/06/2019
The vulnerability described in CVE-2013-4739 represents a critical information disclosure flaw within the Qualcomm MSM camera driver implementation for Linux kernel versions 3.x. This vulnerability specifically affects devices running Android operating systems that incorporate Qualcomm Innovation Center contributions, particularly those utilizing MSM (Media Signal Processor) devices. The flaw exists in the kernel-level camera driver components that handle multimedia processing tasks, making it a significant concern for mobile device security and privacy. The affected code paths are located within the camera_v1 and camera_v2 subsystems, specifically in mercury and jpeg synchronization modules that manage communication between userspace applications and kernel-space camera hardware components.
The technical implementation of this vulnerability stems from improper input validation and memory handling within the ioctl (input/output control) system calls used by the camera driver. Attackers can exploit this weakness by crafting malicious ioctl commands that trigger specific code paths in the kernel driver. The two primary attack vectors involve the MSM_MCR_IOCTL_EVT_GET and MSM_JPEG_IOCTL_EVT_GET ioctl calls, which are designed to retrieve event information from the camera subsystem. When these ioctl calls are improperly constructed, they cause the kernel to copy uninitialized or sensitive data from kernel stack memory regions into user-space buffers without proper sanitization. This occurs because the driver fails to validate the size parameters or properly initialize memory structures before copying data back to userspace, creating a direct information leak channel.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can potentially expose sensitive kernel memory contents including cryptographic keys, session tokens, or other confidential data that might be present in the stack memory at the time of the ioctl call. This information leakage could enable attackers to perform more sophisticated attacks such as privilege escalation, bypassing security mechanisms, or reconstructing memory layouts for further exploitation. The vulnerability affects a wide range of Qualcomm-based Android devices, making it particularly dangerous in mobile environments where users often store sensitive personal and financial information. Security researchers have classified this as a kernel-level information disclosure vulnerability that can be exploited remotely through malicious applications or compromised system components, potentially leading to complete device compromise.
Mitigation strategies for CVE-2013-4739 should focus on both immediate patching and operational security measures. The primary solution involves applying kernel updates from Qualcomm and device manufacturers that properly validate ioctl parameters and sanitize memory before copying data to userspace. System administrators should ensure that all affected devices receive timely security updates and that the kernel driver components are properly patched to prevent uninitialized memory access. Additionally, implementing proper input validation in userspace applications that interact with camera hardware can help reduce attack surface. From an operational perspective, monitoring for suspicious ioctl activity and implementing kernel security modules such as kernel address space layout randomization (KASLR) can provide additional protection layers. This vulnerability aligns with CWE-248, which addresses "Uncaught Exception" in software systems, and represents a specific instance where improper exception handling leads to information disclosure. The ATT&CK framework categorizes this as a privilege escalation technique through kernel exploits, as the leaked information could potentially be used to bypass security controls and gain elevated system privileges. Organizations should conduct thorough vulnerability assessments to identify all affected devices and implement comprehensive monitoring to detect potential exploitation attempts.