CVE-2016-7459 in vCenter Server
Summary
by MITRE
VMware vCenter Server 5.5 before U3e and 6.0 before U2a allows remote authenticated users to read arbitrary files via a (1) Log Browser, (2) Distributed Switch setup, or (3) Content Library XML document containing an external entity declaration in conjunction with an entity reference, related to an XML External Entity (XXE) issue.
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Analysis
by VulDB Data Team • 10/04/2022
The vulnerability identified as CVE-2016-7459 represents a critical XML External Entity (XXE) flaw within VMware vCenter Server versions prior to specific patch releases. This vulnerability exists in both vCenter Server 5.5 before U3e and vCenter Server 6.0 before U2a, creating a significant security risk for organizations relying on these platforms for virtual infrastructure management. The XXE vulnerability stems from insufficient input validation and improper handling of XML data structures within the server's processing logic, allowing malicious actors to exploit multiple attack vectors including Log Browser functionality, Distributed Switch setup operations, and Content Library XML document processing.
The technical exploitation of this vulnerability occurs through the manipulation of XML documents that contain external entity declarations followed by entity references. When authenticated users with appropriate privileges submit specially crafted XML content through any of the three identified vectors, the vCenter Server processes these documents without adequate sanitization of external entity references. This processing behavior enables attackers to access arbitrary files on the underlying operating system where vCenter Server is hosted. The vulnerability is particularly concerning because it requires only authenticated access, meaning that attackers who have obtained valid user credentials can leverage this weakness to escalate their privileges and gain unauthorized access to sensitive system files, configuration data, and potentially other system resources.
From an operational impact perspective, this vulnerability creates a substantial risk to enterprise security infrastructure management. Organizations using affected vCenter Server versions face potential exposure of critical system information including administrative credentials, configuration files, and other sensitive data that may be stored in accessible file locations. The attack surface is broad due to the three distinct exploitation paths, increasing the likelihood that an attacker can find a viable method to compromise the system. Security teams must consider that the vulnerability can be exploited in environments where vCenter Server handles diverse XML-based operations, making it particularly dangerous in complex virtualized infrastructures where multiple systems interact through XML-based protocols.
The mitigation strategies for CVE-2016-7459 involve immediate patching of affected vCenter Server installations to the recommended versions that address the XXE vulnerability. Organizations should also implement network segmentation and access controls to limit exposure of vCenter Server to untrusted networks while ensuring that only authorized personnel can access the system. Additional defensive measures include implementing strict XML input validation procedures, disabling unnecessary XML processing capabilities, and monitoring for suspicious XML-based activities in system logs. This vulnerability aligns with CWE-611, which specifically addresses Improper Restriction of XML External Entity Reference, and represents a significant concern within the ATT&CK framework under the T1059.007 technique for Windows Command and Scripting Interpreter. The vulnerability demonstrates how seemingly routine administrative functions can become attack vectors when proper input sanitization is not implemented, emphasizing the critical importance of secure coding practices and regular security assessments in enterprise infrastructure management systems.