CVE-2017-0866 in Android
Summary
by MITRE
An elevation of privilege vulnerability in the Direct rendering infrastructure of the NVIDIA Tegra X1 where an unchecked input from userspace is passed as a pointer to kfree. This could lead to kernel memory corruption and possible code execution. This issue is rated as moderate. Product: Pixel. Version: N/A. Android ID: A-38415808. References: N-CVE-2017-0866.
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Analysis
by VulDB Data Team • 12/07/2019
The vulnerability identified as CVE-2017-0866 represents a critical elevation of privilege flaw within the NVIDIA Tegra X1's direct rendering infrastructure, specifically affecting Android devices including the Pixel series. This vulnerability stems from improper input validation within the kernel space components that handle graphics rendering operations, creating a pathway for malicious actors to manipulate kernel memory through user-space controlled inputs. The issue manifests when unchecked user-supplied data is directly passed as a pointer argument to the kfree kernel function, which is responsible for freeing memory allocations. This fundamental flaw in input sanitization creates a dangerous condition where arbitrary memory addresses can be targeted for deallocation, potentially leading to kernel memory corruption that compromises system stability and security.
The technical exploitation of this vulnerability occurs through a specific attack vector involving the direct rendering infrastructure's handling of graphics commands. When user-space applications submit rendering requests containing malformed pointer values, these unchecked inputs bypass proper validation mechanisms within the kernel's memory management subsystem. The kfree function, designed to safely release kernel memory, receives these unvalidated pointers and attempts to free memory at arbitrary locations, potentially causing memory corruption that can be leveraged to execute arbitrary code with kernel privileges. This type of vulnerability falls under the CWE-707 category of "Improper Neutralization of Input During Web Page Generation" but specifically manifests in kernel space contexts where the consequences are far more severe than typical web application vulnerabilities. The attack pattern aligns with ATT&CK technique T1068 which describes 'Exploitation for Privilege Escalation' by leveraging kernel-level vulnerabilities to gain elevated system privileges.
The operational impact of CVE-2017-0866 extends beyond simple privilege escalation to encompass potential complete system compromise and data exfiltration capabilities. Successful exploitation allows attackers to execute code with kernel-level privileges, effectively bypassing all standard Android security mechanisms including SELinux policies and application sandboxing. This vulnerability specifically affects devices running Android versions where the affected NVIDIA Tegra X1 graphics driver components are present, making it particularly concerning for mobile platforms where users expect robust security boundaries between applications and system resources. The moderate severity rating belies the critical nature of the vulnerability, as it requires no user interaction for exploitation once the malicious graphics command is submitted, and the privilege escalation can be leveraged to access all system resources including encrypted storage, user credentials, and network communications. The vulnerability demonstrates how graphics processing unit drivers can serve as attack surfaces for kernel-level exploitation, highlighting the importance of proper input validation in all kernel components regardless of their perceived benign nature. Mitigation efforts must focus on updating device firmware and Android system images to patched versions that properly validate all user-supplied inputs before passing them to kernel memory management functions, while also implementing additional runtime protections such as kernel address space layout randomization and stack canaries to make exploitation more difficult.