CVE-2014-9778 in Android
Summary
by MITRE
The vid_dec_set_h264_mv_buffers function in drivers/video/msm/vidc/common/dec/vdec.c in the Qualcomm components in Android before 2016-07-05 on Nexus 5 and 7 (2013) devices does not validate the number of buffers, which allows attackers to gain privileges via a crafted application, aka Android internal bug 28598515 and Qualcomm internal bug CR563694.
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Analysis
by VulDB Data Team • 09/01/2022
The vulnerability described in CVE-2014-9778 represents a critical privilege escalation flaw within the Android multimedia subsystem on Qualcomm-based devices. This issue resides in the video decoder component responsible for handling h264 video decoding operations, specifically within the vdec.c file of the Qualcomm MSM video codec driver. The vulnerability stems from inadequate input validation mechanisms that fail to properly verify the number of buffer allocations requested during video decoding processes. Attackers can exploit this weakness by crafting malicious applications that manipulate buffer parameters in ways that bypass normal security checks, ultimately enabling them to escalate privileges from regular application level access to system-level administrative privileges.
The technical root cause of this vulnerability aligns with CWE-129, which addresses issues related to insufficient input validation, and more specifically with CWE-787, concerning out-of-bounds write vulnerabilities. The flaw occurs in the vid_dec_set_h264_mv_buffers function where the system fails to validate the number of motion vector buffers requested during video decoding operations. This validation gap allows attackers to specify an excessive number of buffers that can overwrite adjacent memory regions or manipulate kernel data structures. The vulnerability is particularly dangerous because it operates at the kernel level within the Android security model, where legitimate applications should not have the capability to manipulate core system resources. The exploitation mechanism leverages the fact that the kernel driver does not perform bounds checking on the buffer count parameter, allowing attackers to trigger memory corruption that can be leveraged for privilege escalation.
The operational impact of this vulnerability is severe and affects a wide range of devices including the Nexus 5 and Nexus 7 (2013) models that shipped with Android versions prior to the 2016-07-05 security patch. These devices represent a significant portion of the Android ecosystem from that era, making the vulnerability particularly dangerous from a threat perspective. The exploitation process typically involves a malicious application that can be installed through normal app distribution channels, requiring no special privileges or physical access to the device. Once successfully exploited, the vulnerability provides attackers with complete system control, enabling them to access sensitive data, modify system files, install malicious software, and potentially compromise the entire device. The vulnerability also aligns with ATT&CK technique T1068, which describes 'Exploitation for Privilege Escalation', and T1547.001, which covers 'Registry Run Keys / Startup Folder', as the privilege escalation can be used to establish persistent access to the compromised system.
Mitigation strategies for this vulnerability require immediate deployment of the security patches released by Google and Qualcomm in their respective security bulletins. Device administrators should ensure all affected devices receive the Android security update from 2016-07-05, which includes the necessary fixes to validate buffer counts in the video decoder component. Additionally, organizations should implement application whitelisting policies to prevent installation of untrusted applications, as the vulnerability can be exploited through legitimate app installation processes. The fix implemented in the patched versions addresses the core validation issue by adding proper bounds checking to ensure that the number of buffers requested does not exceed acceptable limits. Network-level defenses should also include monitoring for suspicious application behavior patterns that might indicate attempts to exploit this vulnerability, though such detection is challenging given the kernel-level nature of the exploit. Regular security audits of device configurations and application permissions should be conducted to maintain defense-in-depth posture against similar vulnerabilities that may exist in other kernel components.