CVE-2017-4919 in vCenter Server
Summary
by MITRE
VMware vCenter Server 5.5, 6.0, 6.5 allows vSphere users with certain, limited vSphere privileges to use the VIX API to access Guest Operating Systems without the need to authenticate.
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Analysis
by VulDB Data Team • 01/06/2021
The vulnerability identified as CVE-2017-4919 affects VMware vCenter Server versions 5.5, 6.0, and 6.5, representing a critical authentication bypass flaw within the virtualization management infrastructure. This vulnerability specifically targets the VIX API functionality that enables vSphere users to interact with guest operating systems, creating a significant security risk for organizations relying on VMware's virtualization platform. The flaw stems from insufficient access controls that allow authenticated users with limited vSphere privileges to leverage the VIX API to gain access to guest operating systems without proper authentication mechanisms.
The technical implementation of this vulnerability resides in the improper validation of user credentials and privilege levels within the VIX API subsystem of vCenter Server. When users with specific, limited vSphere privileges attempt to access guest operating systems through the VIX API, the system fails to properly enforce authentication requirements that should normally be mandatory for guest OS access. This represents a direct violation of the principle of least privilege and demonstrates a failure in the authorization framework that governs access to virtual machine resources. The vulnerability can be exploited by users who possess basic vSphere permissions but lack the elevated privileges typically required to access guest operating systems directly.
From an operational impact perspective, this vulnerability creates a substantial risk for organizations as it allows malicious insiders or compromised accounts with limited privileges to potentially access sensitive data residing within guest operating systems. The attack surface expands significantly since the VIX API is designed for legitimate automation and management tasks, making the exploitation less likely to trigger security monitoring alerts. An attacker could potentially extract confidential information, modify system configurations, or establish persistence within guest operating systems without proper authentication, leading to potential data breaches and system compromise. The vulnerability affects the integrity and confidentiality of virtualized environments and undermines the security posture of organizations relying on VMware infrastructure.
Organizations should immediately apply the vendor-provided patches and updates to address this vulnerability, as the flaw affects multiple versions of VMware vCenter Server that remain in widespread use. The mitigation strategy should include implementing network segmentation to limit access to vCenter Server infrastructure, enforcing strict access controls for vSphere users, and monitoring for unusual VIX API usage patterns. Security teams should also conduct comprehensive assessments of their virtualization environments to identify any potential exploitation attempts. This vulnerability aligns with CWE-285, which addresses improper authorization in software systems, and corresponds to techniques described in the MITRE ATT&CK framework under privilege escalation and credential access domains. Organizations must ensure that their patch management processes include thorough testing of VMware updates to prevent service disruptions while maintaining security posture. The vulnerability demonstrates the critical importance of proper API security implementation and access control enforcement in virtualized environments where multiple users and systems interact with shared resources.