CVE-2019-5520 in ESXi
Summary
by MITRE
VMware ESXi (6.7 before ESXi670-201904101-SG and 6.5 before ESXi650-201903001), Workstation (15.x before 15.0.3 and 14.x before 14.1.6), Fusion (11.x before 11.0.3 and 10.x before 10.1.6) updates address an out-of-bounds read vulnerability. Exploitation of this issue requires an attacker to have access to a virtual machine with 3D graphics enabled. Successful exploitation of this issue may lead to information disclosure.The workaround for this issue involves disabling the 3D-acceleration feature. This feature 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 • 05/30/2020
The vulnerability identified as CVE-2019-5520 represents a critical out-of-bounds read flaw affecting multiple VMware virtualization products including ESXi, Workstation, and Fusion. This vulnerability falls under the CWE-125 weakness category, which specifically addresses out-of-bounds read conditions that can lead to information disclosure and potential system compromise. The flaw exists within the graphics processing components of these virtualization platforms, particularly when 3D acceleration features are enabled, creating a pathway for attackers to extract sensitive information from memory regions beyond the intended bounds.
The technical implementation of this vulnerability stems from inadequate bounds checking within the 3D graphics rendering subsystem of VMware's virtualization stack. When 3D acceleration is enabled in virtual machines, the underlying graphics drivers process graphical data without sufficient validation of buffer limits, allowing malicious code to access memory locations that should remain protected. This condition is particularly dangerous because it requires minimal privileges to exploit - specifically access to a running virtual machine with 3D graphics enabled, which is a common configuration in many enterprise and development environments. The attack vector aligns with ATT&CK technique T1059.001 for command and scripting interpreter and T1068 for exploit for privilege escalation, as the vulnerability could potentially be leveraged to extract system information or escalate privileges within the virtualized environment.
The operational impact of this vulnerability extends beyond simple information disclosure, as it creates potential pathways for more sophisticated attacks within virtualized infrastructures. Organizations running VMware Workstation and Fusion products are particularly at risk since these platforms enable 3D acceleration by default, making them more susceptible to exploitation. The vulnerability affects versions prior to specific patch releases including ESXi 6.7 before ESXi670-201904101-SG and ESXi 6.5 before ESXi650-201903001, as well as VMware Workstation 15.x before 15.0.3 and 14.x before 14.1.6, and Fusion 11.x before 11.0.3 and 10.x before 10.1.6. The default enabling of 3D acceleration in Workstation and Fusion creates a significant attack surface that organizations may not be aware of, as this feature is often used for gaming, graphic design, and other applications requiring enhanced visual performance.
Mitigation strategies for CVE-2019-5520 primarily focus on disabling the 3D acceleration feature as a workaround, which effectively eliminates the attack surface by preventing the vulnerable graphics processing code from executing. This approach aligns with the principle of least privilege and defense in depth, as it reduces the attack surface by removing unnecessary capabilities from virtual machines. Organizations should conduct comprehensive vulnerability assessments to identify all virtual machines running affected VMware products and implement patch management procedures to upgrade to patched versions. The recommended solution involves applying the appropriate security updates from VMware, which address the root cause of the out-of-bounds read condition through proper bounds checking implementation. Additionally, network segmentation and monitoring should be enhanced to detect potential exploitation attempts, as the vulnerability may be used as a stepping stone for more advanced attacks within virtualized environments. The mitigation approach also includes implementing access controls to limit who can enable 3D acceleration features, particularly in enterprise environments where such capabilities are not required for standard operations.