CVE-2019-18389 in virglrenderer
Summary
by MITRE
A heap-based buffer overflow in the vrend_renderer_transfer_write_iov function in vrend_renderer.c in virglrenderer through 0.8.0 allows guest OS users to cause a denial of service, or QEMU guest-to-host escape and code execution, via VIRGL_CCMD_RESOURCE_INLINE_WRITE commands.
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Analysis
by VulDB Data Team • 03/16/2024
This vulnerability exists within the virglrenderer library version 0.8.0 and earlier, specifically in the vrend_renderer_transfer_write_iov function located in vrend_renderer.c. The flaw represents a heap-based buffer overflow that occurs when processing VIRGL_CCMD_RESOURCE_INLINE_WRITE commands, which are typically used for transferring data between guest and host systems in virtualized environments. The vulnerability arises from insufficient bounds checking when handling input data structures that define the transfer operations, allowing maliciously crafted commands to write beyond allocated memory boundaries. This type of vulnerability falls under CWE-121 heap-based buffer overflow classification, where the overflow occurs in heap-allocated memory rather than stack memory, making it particularly dangerous for exploitation in virtualization contexts.
The operational impact of this vulnerability extends beyond simple denial of service to include potential guest-to-host escape scenarios that could enable arbitrary code execution on the host system. When exploited, the buffer overflow allows attackers within the guest operating system to overwrite adjacent memory regions, potentially corrupting critical data structures or injecting executable code that can be leveraged to escalate privileges and achieve full control over the host system. This represents a significant security risk in virtualized environments where guest isolation is paramount for system security. The vulnerability is particularly concerning because it can be triggered through legitimate guest OS operations, making detection and prevention challenging. Attackers could potentially use this vulnerability to bypass virtualization security boundaries, as described in the ATT&CK framework under techniques related to privilege escalation and container escape.
The exploitation of this vulnerability requires that an attacker have access to execute commands within the guest OS, typically through legitimate user accounts or compromised applications. The vulnerability is most impactful in environments where multiple users share virtualized resources or where guest OS users have elevated privileges. Mitigation strategies include immediate patching of virglrenderer to version 0.8.1 or later, which contains the necessary fixes for the buffer overflow issue. Additionally, system administrators should implement strict access controls and monitoring of guest OS activities to detect anomalous behavior that might indicate exploitation attempts. Virtualization administrators should also consider implementing additional security measures such as disabling unnecessary guest-to-host communication channels and using hypervisor-level security features to isolate guest environments more effectively. The vulnerability demonstrates the critical importance of proper input validation in virtualization components, as even legitimate data transfer operations can become attack vectors when proper bounds checking is not implemented.