CVE-2018-6967 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-2018-6966.
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Analysis
by VulDB Data Team • 03/29/2023
The vulnerability identified as CVE-2018-6967 represents a critical out-of-bounds read flaw within the shader translation components of VMware's virtualization platforms. This issue affects multiple product lines including ESXi version 6.7 before the specified patch level, VMware Workstation 14.x before version 14.1.2, and VMware Fusion 10.x before version 10.1.2. The vulnerability specifically resides in the shader translator functionality which processes graphics rendering operations within virtual machine environments, making it particularly concerning for systems that rely heavily on graphical processing capabilities.
The technical nature of this vulnerability stems from improper bounds checking within the shader translation code that handles graphics processing instructions. When a malicious user executes crafted graphics operations within a virtual machine, the shader translator fails to properly validate input data boundaries, leading to memory access violations that can result in information disclosure or system instability. This out-of-bounds read condition occurs during the translation of graphics shaders from high-level representation to executable machine code, a process that is fundamental to rendering graphics within virtualized environments. The flaw does not require elevated privileges to exploit, making it particularly dangerous as normal users within a VM can potentially trigger the vulnerability.
From an operational impact perspective, this vulnerability creates significant risks for organizations utilizing VMware virtualization solutions, as it enables attackers to either extract sensitive information from memory or cause virtual machine crashes. The information disclosure aspect of the vulnerability could potentially expose system memory contents, including potentially sensitive data such as credentials, encryption keys, or application data that might be stored in memory during graphics processing operations. Additionally, the ability to crash virtual machines represents a denial-of-service threat that could disrupt business operations, particularly in environments where multiple virtual machines are running simultaneously. The vulnerability's classification under CWE-125 indicates it falls within the category of out-of-bounds read flaws, which are commonly exploited in memory corruption attacks and represent a significant threat to system stability and data integrity.
The exploitation of CVE-2018-6967 aligns with several techniques documented in the ATT&CK framework under the Tactic of Execution and Defense Evasion. Specifically, this vulnerability could be leveraged as part of a broader attack chain where an initial foothold is established through a compromised user account, followed by exploitation of this graphics processing vulnerability to either gain additional information or destabilize the virtualized environment. The vulnerability's relationship to CVE-2018-6965 and CVE-2018-6966 demonstrates that VMware was addressing a series of related graphics processing flaws within the same product lines, indicating a systemic issue in the shader translation implementation that required comprehensive patching across multiple affected versions. Organizations should prioritize applying the relevant patches provided by VMware to address this vulnerability, as the combination of information disclosure potential and system instability makes this issue particularly dangerous in production environments where virtualization platforms serve critical business functions.
Mitigation strategies should include immediate deployment of VMware's security patches for all affected versions of ESXi, Workstation, and Fusion, along with monitoring for suspicious graphics processing activities that might indicate exploitation attempts. Network segmentation and access controls should be implemented to limit user privileges within virtual environments, while regular security assessments should be conducted to identify other potential vulnerabilities in the virtualization stack. The vulnerability highlights the importance of proper input validation in graphics processing components and serves as a reminder that even seemingly benign functionality like shader translation can represent significant security risks when not properly secured against memory corruption attacks.