CVE-2017-4903 in ESXi
Summary
by MITRE
VMware ESXi 6.5 without patch ESXi650-201703410-SG, 6.0 U3 without patch ESXi600-201703401-SG, 6.0 U2 without patch ESXi600-201703403-SG, 6.0 U1 without patch ESXi600-201703402-SG, and 5.5 without patch ESXi550-201703401-SG; Workstation Pro / Player 12.x prior to 12.5.5; and Fusion Pro / Fusion 8.x prior to 8.5.6 have an uninitialized stack memory usage in SVGA. This issue may allow a guest to execute code on the host.
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Analysis
by VulDB Data Team • 12/26/2020
The vulnerability identified as CVE-2017-4903 represents a critical uninitialized stack memory usage flaw within VMware ESXi hypervisor versions and related products. This issue affects multiple VMware virtualization platforms including ESXi 6.5, 6.0 U3, 6.0 U2, 6.0 U1, and 5.5, along with VMware Workstation Pro/Player 12.x and Fusion Pro/Fusion 8.x. The vulnerability specifically resides in the SVGA (Simple Virtual Graphics Adapter) component, which handles graphics rendering within virtualized environments. The flaw stems from improper initialization of stack memory variables during graphics processing operations, creating potential attack vectors that could be exploited by malicious actors.
The technical nature of this vulnerability falls under CWE-457, which describes the use of uninitialized variables, and represents a classic stack-based buffer overflow scenario. When guest operating systems execute graphics operations through the SVGA interface, the hypervisor fails to properly initialize certain stack memory locations before using them. This uninitialized memory can contain residual data from previous operations, potentially including sensitive information or executable code fragments. The vulnerability allows a malicious guest operating system to manipulate the uninitialized memory values in such a way that they can be leveraged to execute arbitrary code on the host system. This privilege escalation scenario occurs because the hypervisor's graphics processing code does not adequately validate or clear stack memory before reuse, creating a pathway for guest-to-host code execution.
The operational impact of this vulnerability is severe and far-reaching within virtualized environments. An attacker who gains access to a guest virtual machine could potentially leverage this vulnerability to escape the isolation boundaries of the virtual machine and execute code directly on the host system. This would effectively compromise the entire virtualization infrastructure, as the host system typically runs multiple guest VMs and may contain critical system services, databases, and applications. The attack vector requires a guest compromise, which is often achievable through social engineering, phishing attacks, or exploitation of other vulnerabilities in guest operating systems. Once the host is compromised, attackers could potentially access all VMs running on that host, escalate privileges to root/administrator levels, and perform lateral movement throughout the network infrastructure.
Mitigation strategies for CVE-2017-4903 primarily focus on applying the official VMware patches that address the uninitialized memory usage issue. Organizations should immediately deploy the recommended patches for each affected VMware product version, including ESXi650-201703410-SG for ESXi 6.5, ESXi600-201703401-SG for ESXi 6.0 U3, ESXi600-201703403-SG for ESXi 6.0 U2, ESXi600-201703402-SG for ESXi 6.0 U1, ESXi550-201703401-SG for ESXi 5.5, and corresponding updates for Workstation and Fusion products. Additionally, implementing network segmentation and access controls can help limit the potential impact of a successful exploitation attempt. From an ATT&CK framework perspective, this vulnerability maps to techniques such as privilege escalation and execution through hypervisor compromise, making it a critical concern for organizations implementing virtualized security architectures. Regular vulnerability assessments and maintaining up-to-date patch management procedures are essential defensive measures that should be prioritized to protect against this and similar hypervisor-based vulnerabilities.