CVE-2019-5536 in ESXi
Summary
by MITRE
VMware ESXi (6.7 before ESXi670-201908101-SG and 6.5 before ESXi650-201910401-SG), Workstation (15.x before 15.5.0) and Fusion (11.x before 11.5.0) contain a denial-of-service vulnerability in the shader functionality. Successful exploitation of this issue may allow attackers with normal user privileges to create a denial-of-service condition on their own VM. Exploitation of this issue require an attacker to have access to a virtual machine with 3D graphics enabled. It is not enabled by default on ESXi and is enabled by default on Workstation and Fusion.
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Analysis
by VulDB Data Team • 01/29/2024
The vulnerability identified as CVE-2019-5536 represents a critical denial-of-service weakness affecting VMware virtualization platforms including ESXi, Workstation, and Fusion products. This flaw specifically targets the shader functionality within these virtual environments, creating potential for system instability when exploited by malicious actors. The vulnerability exists in multiple product versions where the 3D graphics capabilities have been enabled, with particular attention to ESXi versions prior to specific patch releases and VMware Workstation and Fusion versions before 15.5.0 and 11.5.0 respectively. The security implications extend beyond simple service disruption as this weakness could potentially be leveraged to compromise the integrity of virtual machine operations and overall system availability.
The technical root cause of this vulnerability lies within the improper handling of shader operations within the virtualized graphics subsystem. When 3D graphics are enabled in VMware environments, the system processes complex graphical operations through shader programs that execute within the virtual machine environment. The flaw manifests when these shader operations receive malformed or specially crafted input that causes the graphics processing unit to enter an unstable state or crash. This type of vulnerability typically falls under CWE-121 which describes "Stack-based Buffer Overflow" conditions, though the specific implementation may involve heap corruption or improper memory management during shader execution. The exploitation requires an attacker to possess access to a running virtual machine that has 3D graphics enabled, making this a privilege-based vulnerability that cannot be exploited remotely but rather requires local access to the target system.
The operational impact of CVE-2019-5536 extends beyond simple service interruption as it can create cascading effects within virtualized environments. When exploited successfully, the vulnerability allows attackers with normal user privileges to cause their own virtual machine to become unresponsive or crash entirely, potentially leading to data loss or service disruption for the virtualized applications running within that environment. The vulnerability's impact is particularly concerning in enterprise environments where multiple virtual machines may be running on a single host system, as a single compromised VM could potentially affect the entire host's performance and stability. From an attack perspective, this vulnerability aligns with ATT&CK technique T1499.004 which covers "Endpoint Denial of Service" and represents a form of resource exhaustion that can be achieved through carefully crafted graphical operations. The fact that 3D graphics are enabled by default on Workstation and Fusion but disabled on ESXi creates different risk profiles across the product line, with Workstation and Fusion presenting higher exposure levels.
Mitigation strategies for CVE-2019-5536 primarily focus on implementing the vendor-provided patches and updates that address the specific shader handling issues within the affected VMware products. Organizations should immediately upgrade to the patched versions of ESXi, Workstation, and Fusion to eliminate the vulnerability at its source. Additionally, administrators should consider disabling 3D graphics capabilities on virtual machines where such functionality is not required for legitimate business operations, particularly in environments where security is paramount. The implementation of network segmentation and access controls can help limit the potential impact of this vulnerability by reducing the attack surface and ensuring that only authorized users have access to virtual machines with 3D graphics enabled. Security monitoring should include detection of unusual graphics processing patterns that might indicate exploitation attempts, and system administrators should maintain regular patching schedules to address similar vulnerabilities that may emerge in the future. The vulnerability also highlights the importance of maintaining awareness of the specific attack vectors that exist within virtualized environments and implementing appropriate security controls that address both the virtualization platform and the guest operating systems running within it.