CVE-2018-6966 in ESXi
Summary
by MITRE
VMware ESXi (6.7 before ESXi670-201806401-BG), Workstation (14.x before 14.1.2), and Fusion (10.x before 10.1.2) contain an out-of-bounds read vulnerability in the shader translator. Successful exploitation of this issue may lead to information disclosure or may allow attackers with normal user privileges to crash their VMs, a different vulnerability than CVE-2018-6965 and CVE-2018-6967.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability identified as CVE-2018-6966 represents a critical out-of-bounds read flaw within the graphics shader translation components of VMware's virtualization platforms. This issue affects multiple products including ESXi version 6.7 before build ESXi670-201806401-BG, VMware Workstation 14.x before version 14.1.2, and VMware Fusion 10.x before version 10.1.2. The vulnerability resides in the shader translator module which processes graphics rendering instructions for virtual machines, making it particularly concerning for environments where graphical intensive applications are commonly executed.
The technical implementation of this vulnerability stems from inadequate bounds checking within the shader translation logic that processes graphics commands from guest operating systems. When a malicious user or application submits specially crafted graphics instructions to a virtual machine, the shader translator fails to properly validate input boundaries before accessing memory locations. This allows an attacker to read memory contents beyond the intended buffer boundaries, potentially exposing sensitive information stored in adjacent memory regions. The flaw operates at the level of graphics processing unit virtualization where guest operating systems pass rendering commands through the hypervisor to the underlying hardware, creating a potential information disclosure vector that could reveal system memory contents including kernel data, user credentials, or other confidential information.
From an operational impact perspective, this vulnerability creates significant security implications for virtualized environments where multiple users share the same physical infrastructure. Attackers with normal user privileges within a guest operating system can potentially exploit this vulnerability to either extract sensitive information from memory or cause virtual machine crashes, effectively creating a denial of service condition. The vulnerability's classification as a remote code execution risk is particularly concerning given that it can be triggered through standard graphics rendering operations without requiring elevated privileges. The separate nature of this vulnerability from CVE-2018-6965 and CVE-2018-6967 indicates it operates through distinct code paths, suggesting multiple attack surfaces within the graphics processing subsystem of VMware's virtualization products.
The security implications extend beyond simple information disclosure to encompass potential privilege escalation scenarios within virtualized environments. According to CWE classification, this vulnerability maps to CWE-125: "Out-of-bounds Read" which represents a fundamental memory safety issue that can lead to system compromise when combined with other vulnerabilities. From an ATT&CK framework perspective, this vulnerability could be leveraged as part of a broader attack chain under techniques such as T1059.007: "Command and Scripting Interpreter: PowerShell" or T1068: "Exploitation for Privilege Escalation" when combined with other exploitation methods. Organizations utilizing VMware virtualization platforms should implement immediate mitigations including applying the vendor patches released for ESXi 6.7, Workstation 14.1.2, and Fusion 10.1.2 versions, as well as implementing network segmentation and monitoring for suspicious graphics processing activity that could indicate exploitation attempts. The vulnerability underscores the critical importance of maintaining up-to-date virtualization software and implementing comprehensive security controls around graphics-intensive applications in virtualized environments.