CVE-2017-4924 in ESXi
Summary
by MITRE
VMware ESXi (ESXi 6.5 without patch ESXi650-201707101-SG), Workstation (12.x before 12.5.7) and Fusion (8.x before 8.5.8) contain an out-of-bounds write vulnerability in SVGA device. This issue may allow a guest to execute code on the host.
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Analysis
by VulDB Data Team • 01/13/2021
The vulnerability identified as CVE-2017-4924 represents a critical out-of-bounds write flaw within the SVGA (Simple Virtual Graphics Adapter) device implementation across multiple VMware virtualization products including ESXi, Workstation, and Fusion. This issue resides in the graphics subsystem that handles virtualized display operations, creating a potential pathway for privilege escalation and arbitrary code execution within the host environment. The vulnerability specifically affects VMware ESXi version 6.5 without the patch ESXi650-201707101-SG, VMware Workstation versions 12.x prior to 12.5.7, and VMware Fusion versions 8.x before 8.5.8, indicating a widespread impact across the virtualization ecosystem.
The technical flaw manifests as an improper bounds checking mechanism within the SVGA device driver's handling of graphics commands and data structures. When a malicious guest operating system attempts to process specific graphics operations through the SVGA interface, the driver fails to validate array indices or buffer boundaries before writing data to memory locations. This out-of-bounds write condition allows an attacker to overwrite adjacent memory regions, potentially corrupting critical data structures or executing arbitrary code with the privileges of the host operating system. The vulnerability is particularly dangerous because it leverages the graphics processing capabilities that are typically less scrutinized than other system components, making it an attractive target for sophisticated attackers seeking persistent access to host systems.
The operational impact of this vulnerability extends beyond simple code execution, as it fundamentally undermines the security isolation that virtualization platforms are designed to maintain between guest and host environments. An attacker who successfully exploits this vulnerability can achieve complete host compromise, potentially leading to data theft, lateral movement within network infrastructure, or establishment of persistent backdoors. The attack vector requires a guest operating system to be running within the vulnerable VMware environment, which means that the vulnerability is particularly concerning for organizations that allow untrusted users to execute code within virtual machines or for environments where guest VMs are not properly isolated. This issue aligns with CWE-787: "Out-of-bounds Write" and represents a classic example of how virtualization security boundaries can be circumvented through flaws in device emulation components.
The exploitation of CVE-2017-4924 demonstrates several characteristics that align with ATT&CK framework tactics including privilege escalation and defense evasion. The vulnerability enables an attacker to move from a guest environment to a host environment, effectively escalating privileges from guest-level to host-level access, which corresponds to ATT&CK technique T1068: "Exploitation for Privilege Escalation." Additionally, the use of graphics device manipulation to achieve code execution represents a sophisticated approach to bypassing traditional security controls, potentially evading endpoint detection and response systems that may not monitor graphics processing operations. Organizations should consider this vulnerability when implementing security controls and incident response procedures, as it represents a potential attack pathway that could be used to establish long-term access to virtualized environments.
Mitigation strategies for CVE-2017-4924 focus primarily on applying the appropriate vendor patches and updates to eliminate the out-of-bounds write condition. VMware released patches for ESXi, Workstation, and Fusion that address the specific memory handling issues within the SVGA device driver. System administrators should prioritize applying these updates across all affected virtualization platforms, particularly in environments where guest VMs may be running untrusted code or where security isolation is paramount. Additional defensive measures include implementing network segmentation to limit guest VM access to critical host resources, monitoring for unusual graphics processing patterns that might indicate exploitation attempts, and ensuring that virtualization environments are properly configured with appropriate access controls and user permissions. Organizations should also consider implementing virtualization-specific security monitoring solutions that can detect anomalous behavior in graphics device operations and provide early warning of potential exploitation attempts. The vulnerability underscores the importance of maintaining current security patches across all virtualization components and highlights the need for comprehensive security testing of device emulation code within virtualized environments.