CVE-2016-8443 in Android
Summary
by MITRE
Possible unauthorized memory access in the hypervisor. Incorrect configuration provides access to subsystem page tables. Product: Android. Versions: Kernel 3.18. Android ID: A-32576499. References: QC-CR#964185.
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Analysis
by VulDB Data Team • 01/04/2017
The vulnerability identified as CVE-2016-8443 represents a critical hypervisor-level security flaw within the Android kernel version 3.18, specifically affecting the virtualization subsystem. This issue stems from improper configuration of memory management controls that inadvertently grants unauthorized access to subsystem page tables through the hypervisor layer. The vulnerability exploits a fundamental weakness in the kernel's virtual memory management system where privileged memory access controls fail to properly isolate virtual machine memory spaces from the host system. The Android ID A-32576499 indicates this was tracked as a significant security concern within Google's internal vulnerability management system, while the reference to QC-CR#964185 suggests it was also documented in Qualcomm's internal tracking mechanisms. The root cause lies in the hypervisor's failure to maintain proper memory segmentation boundaries, creating a potential attack vector that could allow malicious code to access sensitive memory regions that should remain protected from unauthorized access.
The technical implementation of this vulnerability occurs at the kernel level where the hypervisor component responsible for managing virtual machine execution contexts fails to properly enforce memory access controls. When the kernel processes memory management requests, it incorrectly configures the page table entries that define which memory regions are accessible to different subsystems. This misconfiguration allows for potential memory disclosure attacks where an attacker could potentially read memory contents from other virtual machines or from the host kernel itself. The flaw specifically affects the interaction between the hypervisor and the kernel's memory management unit, where page table manipulation routines do not properly validate access permissions. This type of vulnerability falls under the CWE-284 access control weakness category, specifically dealing with improper access control mechanisms in virtualized environments. The vulnerability could be exploited through carefully crafted memory access patterns that manipulate the hypervisor's page table configuration, potentially allowing for information disclosure and privilege escalation attacks.
The operational impact of CVE-2016-8443 extends beyond simple memory disclosure, as it fundamentally compromises the security isolation that virtualization technologies are designed to provide. Mobile devices running affected Android versions could experience complete system compromise, with attackers potentially gaining access to sensitive data stored in memory, including cryptographic keys, user credentials, and application data. The vulnerability affects the core security model of Android's virtualization implementation, which relies on proper hypervisor memory management to maintain separation between different execution contexts. This flaw could enable attackers to perform cross-vm memory attacks, potentially allowing them to extract information from other virtual machines running on the same physical device. The impact is particularly severe in enterprise environments where mobile devices may be running multiple virtualized applications or security contexts. According to ATT&CK framework, this vulnerability maps to techniques involving privilege escalation and credential access, as attackers could leverage the unauthorized memory access to obtain sensitive information that would normally be protected by proper memory isolation. The vulnerability's exploitation could also facilitate more advanced attacks such as kernel exploitation or rootkit deployment, as the attacker gains access to kernel memory structures that should remain protected.
Mitigation strategies for CVE-2016-8443 require immediate system updates and configuration changes to address the hypervisor memory management flaw. Organizations should prioritize applying the latest Android security patches that include kernel updates addressing this specific vulnerability. The recommended approach involves updating the kernel to a version that properly enforces memory access controls within the hypervisor layer, ensuring that page table configurations are correctly validated before being applied. System administrators should also implement additional monitoring for suspicious memory access patterns and consider disabling unnecessary virtualization features that could exacerbate the vulnerability. The fix typically involves strengthening the hypervisor's page table management routines to properly validate access permissions and prevent unauthorized memory access. Security teams should conduct comprehensive vulnerability assessments to identify devices running affected kernel versions and ensure proper patch management procedures are in place. Additionally, implementing memory protection mechanisms such as kernel address space layout randomization and stack canaries can provide additional defense in depth against exploitation attempts. The vulnerability's classification under CWE-284 emphasizes the need for proper access control implementation, while ATT&CK's privilege escalation techniques highlight the importance of maintaining strict memory isolation boundaries in virtualized environments.