CVE-2019-16508 in Chrome OS
Summary
by MITRE
The Imagination Technologies driver for Chrome OS before R74-11895.B, R75 before R75-12105.B, and R76 before R76-12208.0.0 allows attackers to trigger an Integer Overflow and gain privileges via a malicious application. This occurs because of intentional access for the GPU process to /dev/dri/card1 and the PowerVR ioctl handler, as demonstrated by PVRSRVBridgeSyncPrimOpCreate.
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Analysis
by VulDB Data Team • 12/29/2023
The vulnerability described in CVE-2019-16508 represents a critical privilege escalation flaw within the Imagination Technologies GPU driver implementation in Chrome OS systems. This issue affects specific release versions of Chrome OS including R74, R75, and R76, where the kernel-level graphics driver components contain a fundamental design flaw that allows malicious applications to manipulate system privileges. The vulnerability specifically resides in the PowerVR ioctl handler implementation, which provides direct hardware access mechanisms for GPU operations. Attackers can exploit this weakness by crafting malicious applications that leverage the intentional access permissions granted to the GPU process for the /dev/dri/card1 device node, effectively bypassing normal security boundaries that should protect system integrity.
The technical root cause of this vulnerability stems from an integer overflow condition within the PVRSRVBridgeSyncPrimOpCreate ioctl handler function. This particular ioctl interface is designed to manage synchronization primitives for GPU operations, but the implementation fails to properly validate input parameters before performing arithmetic operations that could result in integer wraparound. When malicious input values are passed to this function, the integer overflow can lead to memory corruption or control flow manipulation, enabling attackers to escalate privileges from normal user-level processes to kernel-level operations. The vulnerability is particularly dangerous because it operates at the kernel level where the GPU process has been granted explicit access to the graphics device through the /dev/dri/card1 interface, making it a direct pathway to system compromise.
The operational impact of this vulnerability extends far beyond simple privilege escalation, as it represents a complete breakdown in the Chrome OS security model. Successful exploitation allows attackers to execute arbitrary code with kernel privileges, potentially leading to full system compromise, data theft, or persistent backdoor installation. The attack vector is particularly concerning because it requires only a malicious application to be executed, without requiring physical access or additional attack surfaces. This vulnerability affects the entire Chrome OS ecosystem and impacts not just individual devices but also enterprise deployments where Chromebooks are used as primary computing platforms. The integer overflow occurs during synchronization primitive creation, which is a common operation in graphics processing, making the exploit relatively easy to trigger and maintain.
Mitigation strategies for this vulnerability must address both the immediate security gap and the underlying architectural issues that enabled the flaw. The primary recommended action is to update all affected Chrome OS devices to versions that contain the patched driver implementations, specifically targeting releases R74-11895.B, R75-12105.B, and R76-12208.0.0 or later. Organizations should implement strict application whitelisting policies to prevent execution of untrusted applications that might attempt to exploit this vulnerability. Additionally, system administrators should monitor for any unusual GPU process behavior or unexpected access patterns to /dev/dri/card1. From a security architecture perspective, this vulnerability highlights the importance of input validation and integer overflow protection in kernel-level code, aligning with CWE-190 which specifically addresses integer overflow conditions. The flaw also demonstrates the risks associated with overly permissive device access controls and the need for principle of least privilege implementation in graphics driver interfaces, which corresponds to ATT&CK technique T1068 related to exploit for privilege escalation through local system services.