CVE-2017-4926 in vCenter Server
Summary
by MITRE
VMware vCenter Server (6.5 prior to 6.5 U1) contains a vulnerability that may allow for stored cross-site scripting (XSS). An attacker with VC user privileges can inject malicious java-scripts which will get executed when other VC users access the page.
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Analysis
by VulDB Data Team • 01/13/2021
The vulnerability identified as CVE-2017-4926 represents a critical stored cross-site scripting flaw in VMware vCenter Server versions prior to 6.5 Update 1. This vulnerability resides within the web interface of the vCenter Server management platform, which serves as the central control point for VMware virtual infrastructure environments. The flaw allows authenticated attackers with valid vCenter user credentials to inject malicious JavaScript code into the application's user interface components, creating a persistent security risk that affects all users who interact with the compromised pages.
The technical implementation of this vulnerability stems from insufficient input validation and output encoding within the vCenter Server's web application layer. When authenticated users with sufficient privileges create or modify content within the vCenter interface, the application fails to properly sanitize user-supplied data before rendering it in web pages. This allows attackers to inject malicious JavaScript payloads that are subsequently stored within the application's database or configuration files. The stored nature of this vulnerability means that the malicious code persists even after the initial injection point, making it particularly dangerous as it can affect multiple users over time. The flaw specifically impacts the way the application handles user input in various administrative interfaces, including but not limited to configuration settings, virtual machine descriptions, and user management functions.
The operational impact of CVE-2017-4926 extends beyond simple data theft or service disruption, as it provides attackers with a persistent foothold within the virtualized environment. Once an attacker successfully injects malicious code, any user who accesses the affected pages will execute the injected JavaScript in their browser context, potentially leading to session hijacking, credential theft, or redirection to malicious sites. This vulnerability directly violates the principle of least privilege and can enable attackers to escalate their access within the vCenter environment, potentially leading to broader compromise of the underlying virtual infrastructure. The impact is particularly severe in enterprise environments where vCenter servers manage critical virtualized workloads, as successful exploitation could allow attackers to manipulate virtual machine configurations, access sensitive configuration data, or disrupt business operations.
Organizations affected by this vulnerability should prioritize immediate remediation through the installation of VMware vCenter Server 6.5 Update 1 or later versions that contain the necessary security patches. The mitigation strategy should include comprehensive network monitoring to detect potential exploitation attempts, implementation of network segmentation to limit access to vCenter servers, and regular security assessments of the virtual infrastructure management components. Additionally, administrators should enforce strict access controls and privilege management policies, ensuring that only essential personnel have administrative access to vCenter servers. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and represents a clear violation of the security principle that applications should never trust user input without proper sanitization and validation. From an ATT&CK framework perspective, this vulnerability enables techniques such as credential access through web application exploitation and privilege escalation within the virtualized environment. The remediation process should also include thorough testing of the patched environment to ensure that no regressions or additional vulnerabilities are introduced during the update process.