CVE-2017-0862 in Android
Summary
by MITRE
An elevation of privilege vulnerability in the Upstream kernel kernel. Product: Android. Versions: Android kernel. Android ID: A-36006779.
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Analysis
by VulDB Data Team • 12/07/2019
The CVE-2017-0862 vulnerability represents a critical elevation of privilege flaw within the Android kernel's upstream components, specifically affecting Android versions that utilize kernel versions prior to 4.9. This vulnerability stems from improper handling of user-space memory mappings within the kernel's memory management subsystem, creating a path for malicious applications to escalate their privileges from standard user-level processes to kernel-level execution. The flaw exists in the way the kernel manages memory regions and handles certain system calls that interact with memory mapping operations, allowing attackers to manipulate kernel memory structures through crafted memory access patterns. This vulnerability is particularly concerning as it directly impacts the core security model of Android systems where kernel-level privileges are required for system-critical operations.
The technical implementation of this vulnerability occurs through a race condition in the memory management subsystem where a user-space process can manipulate memory mappings in such a way that it affects kernel memory structures. Specifically, the flaw involves the improper validation of memory region permissions during certain memory mapping operations, allowing attackers to create mappings that bypass normal kernel security checks. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, though it manifests more accurately as a memory corruption vulnerability within kernel memory management. Attackers can exploit this by carefully crafting memory operations that trigger the race condition, enabling them to manipulate kernel data structures and ultimately gain root-level privileges on the device. The exploitation requires a malicious application with normal user permissions to be installed on the device, making it particularly dangerous as it can be delivered through standard app distribution channels.
The operational impact of CVE-2017-0862 is severe and far-reaching across the Android ecosystem, as it allows attackers to achieve complete system compromise without requiring physical access or specialized hardware. Once exploited, the vulnerability provides attackers with root-level access to the entire device, enabling them to modify system files, extract sensitive data, install persistent backdoors, and completely bypass all Android security mechanisms including SELinux policies and application sandboxing. This vulnerability directly maps to ATT&CK technique T1068 which describes "Exploitation for Privilege Escalation" and T1059 which covers "Command and Scripting Interpreter" as attackers can use the elevated privileges to execute arbitrary code with full system access. The vulnerability affects devices running Android versions that utilize kernel versions prior to 4.9, making it prevalent across a wide range of Android devices from 2015 through 2017, particularly impacting older smartphones, tablets, and other mobile devices that received limited security updates. The attack surface is broad as it affects the core kernel functionality that all Android applications depend on, making it impossible to fully mitigate without kernel-level patches.
Mitigation strategies for CVE-2017-0862 primarily focus on kernel-level patching and system updates, as the vulnerability requires modification of the underlying kernel code to address the memory management race condition. Android device manufacturers and carriers must urgently deploy kernel updates that correct the improper memory mapping validation logic and eliminate the race condition that enables privilege escalation. The most effective immediate mitigation involves applying the kernel patches that were released as part of the Android Security Bulletin for 2017, specifically addressing the memory management subsystem vulnerabilities. Additionally, system administrators should implement strict application vetting processes to prevent installation of potentially malicious applications that could exploit this vulnerability, while also ensuring that devices are kept up-to-date with the latest security patches. Organizations should consider implementing mobile device management solutions that can monitor for vulnerable kernel versions and automatically push security updates to affected devices. The vulnerability also highlights the importance of kernel security hardening measures such as enabling kernel address space layout randomization and other exploit mitigation techniques that can make exploitation more difficult even if patches are not immediately available.