CVE-2018-6981 in ESXi
Summary
by MITRE
VMware ESXi 6.7 without ESXi670-201811401-BG and VMware ESXi 6.5 without ESXi650-201811301-BG, VMware ESXi 6.0 without ESXi600-201811401-BG, VMware Workstation 15, VMware Workstation 14.1.3 or below, VMware Fusion 11, VMware Fusion 10.1.3 or below contain uninitialized stack memory usage in the vmxnet3 virtual network adapter which may allow a guest to execute code on the host.
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Analysis
by VulDB Data Team • 06/13/2023
The vulnerability identified as CVE-2018-6981 represents a critical security flaw in VMware's virtualization infrastructure affecting multiple product versions including ESXi 6.7, 6.5, and 6.0, along with VMware Workstation and Fusion products. This issue stems from improper initialization of stack memory within the vmxnet3 virtual network adapter implementation, creating a potential pathway for privilege escalation attacks. The flaw specifically manifests when guest operating systems interact with the virtual network adapter, potentially enabling malicious code execution on the underlying host system. The vulnerability falls under the CWE-457 category of "Use of Uninitialized Variable" and aligns with ATT&CK technique T1068 which covers "Exploitation for Privilege Escalation" and T1059 which addresses "Command and Scripting Interpreter" as attackers could leverage this to execute arbitrary commands on the host. The affected VMware products include ESXi versions 6.7, 6.5, and 6.0, along with VMware Workstation 15 and versions 14.1.3 and below, as well as VMware Fusion 11 and versions 10.1.3 and below, indicating a broad impact across the virtualization ecosystem. The technical implementation involves the vmxnet3 network driver where stack memory is allocated but not properly initialized before use, creating potential information disclosure and code execution opportunities. This flaw allows a malicious guest operating system to craft specific network packets that trigger the uninitialized memory usage, potentially leading to arbitrary code execution with host privileges. The vulnerability demonstrates a classic buffer overflow scenario where uninitialized memory contents are accessed, potentially exposing sensitive data or enabling attackers to inject and execute malicious code within the host environment. The impact extends beyond simple information disclosure as it fundamentally compromises the isolation guarantees that virtualization platforms are designed to provide, undermining the security model of virtualized environments. Organizations utilizing these affected VMware products face significant risk of unauthorized access and potential complete system compromise, as attackers could leverage this vulnerability to establish persistent access to host systems. The remediation strategy requires immediate deployment of the vendor-provided patches ESXi670-201811401-BG for ESXi 6.7, ESXi650-201811301-BG for ESXi 6.5, and ESXi600-201811401-BG for ESXi 6.0, along with updating VMware Workstation and Fusion to supported versions. Additionally, implementing network segmentation and access controls can help limit the potential impact of such vulnerabilities. The vulnerability also highlights the importance of proper memory initialization practices in virtualized environments where guest and host systems share underlying hardware resources, emphasizing the need for comprehensive security testing of virtualization components. This flaw serves as a reminder of the critical nature of maintaining up-to-date virtualization infrastructure and the potential consequences of delayed patch deployment in enterprise environments. Security teams should conduct thorough vulnerability assessments across their VMware environments to identify and remediate affected systems, while also implementing monitoring solutions to detect potential exploitation attempts targeting this specific vulnerability. The broader implications suggest that similar issues may exist in other virtualization components, warranting additional scrutiny of virtualized infrastructure security controls.