CVE-2019-5516 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 vulnerability with the vertex shader functionality. 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 or may allow attackers with normal user privileges to create a denial-of-service condition on their own VM. 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 • 05/29/2020
The vulnerability identified as CVE-2019-5516 represents a critical out-of-bounds read flaw within the vertex shader implementation of VMware's virtualization products. This issue affects multiple product lines including ESXi hypervisor versions 6.7 and 6.5, VMware Workstation versions 14.x and 15.x, and VMware Fusion versions 10.x and 11.x. The vulnerability resides in the graphics processing subsystem where vertex shaders are executed, making it particularly dangerous in environments where 3D acceleration is utilized. According to CWE-125, this represents an out-of-bounds read condition that can potentially expose sensitive memory contents or cause system instability. The vulnerability is classified under the ATT&CK technique T1059.007 for Command and Scripting Interpreter: PowerShell and T1068 for Exploitation for Privilege Escalation, as attackers could leverage this to gain unauthorized access to information or disrupt virtual machine operations.
The technical exploitation of this vulnerability requires specific conditions to be met, including access to a virtual machine with 3D graphics enabled and the ability to execute malicious code within that environment. The flaw occurs when vertex shader processing routines fail to properly validate input data boundaries, allowing attackers to read memory locations beyond the intended buffer limits. This can result in information disclosure where sensitive data from adjacent memory regions becomes accessible to unauthorized users. The vulnerability is particularly concerning because it can be exploited by users with normal privileges, meaning that even unprivileged attackers within a VM could potentially cause denial-of-service conditions or extract confidential information from the host system or other VMs. The attack vector requires the 3D acceleration feature to be active, which is enabled by default in Workstation and Fusion products but disabled by default in ESXi.
The operational impact of CVE-2019-5516 extends beyond simple denial-of-service scenarios to potentially compromise system integrity and confidentiality. When exploited, the vulnerability can lead to information disclosure that may include sensitive data from memory regions containing system credentials, encryption keys, or other confidential information. The denial-of-service aspect can disrupt virtualized environments by causing VM crashes or system instability, potentially affecting multiple users in shared virtualization infrastructures. Organizations running virtualized environments with 3D graphics capabilities face significant risk, particularly those using Workstation or Fusion products where the 3D acceleration feature is enabled by default. The vulnerability affects both server and desktop virtualization scenarios, making it relevant for enterprises with diverse computing environments that utilize VMware's virtualization solutions.
Mitigation strategies for CVE-2019-5516 focus on both immediate defensive measures and long-term remediation approaches. The primary workaround involves disabling 3D acceleration features on affected systems, which effectively neutralizes the exploit vector while maintaining core virtualization functionality. This approach aligns with defensive cybersecurity practices outlined in NIST SP 800-53 and ISO/IEC 27001 frameworks, particularly in controlling access to system resources and implementing least privilege principles. Organizations should prioritize applying official VMware patches and updates as soon as they become available, with the specific fixes addressing ESXi670-201904101-SG and ESXi650-201903001 for hypervisor components, and updated versions for Workstation and Fusion products. Additionally, implementing network segmentation and access controls can help limit the potential impact if exploitation occurs, while regular security assessments and monitoring of virtualization environments can detect anomalous behavior indicative of attempted exploitation. The vulnerability serves as a reminder of the importance of securing virtualized environments and the need for comprehensive patch management programs that address both hypervisor and guest operating system components.