CVE-2015-8943 in Android
Summary
by MITRE
drivers/video/msm/mdss/mdss_mdp_util.c in the Qualcomm components in Android before 2016-08-05 on Nexus 5 devices does not verify that a mapping exists before proceeding with an unmap operation, which allows attackers to gain privileges via a crafted application, aka Android internal bug 28815158 and Qualcomm internal bugs CR794217 and CR836226.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 09/12/2022
The vulnerability identified as CVE-2015-8943 represents a critical privilege escalation flaw within the Android operating system's graphics driver components, specifically affecting Qualcomm-based devices including the Nexus 5 model. This issue resides in the mdss_mdp_util.c file within the Qualcomm MSM (Multi-System Module) driver stack, which manages display processing and graphics operations. The flaw manifests as a missing validation check during memory management operations, creating a potential path for malicious applications to execute arbitrary code with elevated privileges. The vulnerability was particularly concerning because it affected devices running Android versions prior to the 2016-08-05 security patch release, leaving millions of devices exposed to potential exploitation. This type of vulnerability falls under the CWE-119 weakness category, which deals with weak memory management practices and improper handling of memory mapping operations. The issue demonstrates a classic improper validation scenario where the system fails to verify the existence of a memory mapping before attempting to unmap it, creating a potential for use-after-free conditions or memory corruption that could be exploited by malicious actors.
The technical exploitation of this vulnerability occurs through a crafted application that deliberately attempts to perform an unmapping operation on a memory region that has already been freed or never properly allocated. When the driver processes this invalid unmap request, it fails to validate whether the mapping actually exists before proceeding with the operation, which can result in memory corruption or privilege escalation. This flaw operates at the kernel level within the Android graphics subsystem, specifically within the MSM display driver component that handles multimedia processing and display management. The attack vector requires a malicious application to be installed on the device, as the vulnerability cannot be exploited remotely but rather through local code execution within the context of a compromised application. This type of exploitation aligns with ATT&CK technique T1068, which covers the use of local privilege escalation techniques to gain elevated system access. The vulnerability's impact extends beyond simple code execution as it allows attackers to bypass Android's security model and potentially access sensitive system resources or escalate their privileges to root level access.
The operational impact of CVE-2015-8943 is significant for organizations and individuals using affected Android devices, particularly those in environments where mobile security is critical. Devices that were vulnerable included not just the Nexus 5 but other Qualcomm-based Android smartphones and tablets that had not yet received the relevant security patch updates. The vulnerability could enable attackers to install persistent backdoors, access encrypted data, modify system files, or extract sensitive user information from the device. Security researchers noted that the flaw was particularly dangerous because it could be exploited by applications that were already running on the device, making detection more challenging. The vulnerability also highlighted the complexity of mobile security architectures where multiple vendors and component layers must work together to maintain system integrity. Organizations using mobile device management solutions had to urgently patch affected devices or implement additional security controls to protect against potential exploitation. The vulnerability's discovery also contributed to discussions around the need for better memory management practices in kernel-level drivers and the importance of proper validation checks in security-critical code segments. The affected Qualcomm internal bugs CR794217 and CR836226 indicate that this issue was not isolated but part of a broader pattern of memory management flaws in Qualcomm's driver implementations. The Android internal bug reference 28815158 shows that this vulnerability was tracked and addressed through the standard Android security update process, emphasizing the importance of timely patch deployment and the interconnected nature of mobile security vulnerabilities across different software layers.