CVE-2014-9104 in Access Server
Summary
by MITRE
Multiple cross-site request forgery (CSRF) vulnerabilities in the XML-RPC API in the Desktop Client in OpenVPN Access Server 1.5.6 and earlier allow remote attackers to hijack the authentication of administrators for requests that (1) disconnecting established VPN sessions, (2) connect to arbitrary VPN servers, or (3) create VPN profiles and execute arbitrary commands via crafted API requests.
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Analysis
by VulDB Data Team • 04/07/2018
The vulnerability CVE-2014-9104 represents a critical cross-site request forgery flaw in the XML-RPC API of OpenVPN Access Server desktop client versions 1.5.6 and earlier. This vulnerability resides within the authentication mechanism of the desktop client component, which is designed to provide administrative access to VPN services. The flaw enables remote attackers to manipulate authenticated sessions without possessing valid credentials, creating a significant security risk for organizations relying on OpenVPN Access Server for their network infrastructure.
The technical implementation of this vulnerability stems from the absence of proper CSRF protection mechanisms within the XML-RPC API endpoints. When administrators interact with the desktop client, their authentication tokens are automatically included in API requests without proper validation of the request origin or request integrity. This allows attackers to craft malicious requests that appear to originate from legitimate administrative sessions, bypassing the authentication layer entirely. The vulnerability specifically affects three critical operational functions including session disconnection, arbitrary VPN server connections, and VPN profile creation with command execution capabilities.
The operational impact of this vulnerability is severe and multifaceted, as it grants attackers full administrative privileges over the OpenVPN Access Server environment. An attacker who successfully exploits this CSRF vulnerability can disconnect legitimate user sessions, effectively performing denial-of-service attacks against authorized users. Additionally, the ability to connect to arbitrary VPN servers allows for unauthorized network access and potential data exfiltration. The most dangerous aspect involves the creation of VPN profiles and execution of arbitrary commands, which could enable attackers to establish persistent backdoors, modify server configurations, or gain complete control over the VPN infrastructure. This vulnerability directly maps to CWE-352, which defines Cross-Site Request Forgery, and aligns with ATT&CK technique T1078.004 for Valid Accounts and T1059.001 for Command and Scripting Interpreter, as it enables unauthorized command execution through compromised administrative sessions.
Organizations affected by this vulnerability should immediately implement multiple layers of mitigation strategies to protect their OpenVPN Access Server deployments. The most effective immediate solution involves upgrading to a patched version of OpenVPN Access Server that includes proper CSRF token validation in the XML-RPC API endpoints. Network administrators should also implement additional security controls such as restricting access to the XML-RPC API through firewall rules, implementing IP whitelisting for administrative interfaces, and deploying network monitoring solutions to detect anomalous API activity patterns. The implementation of CSRF tokens for all administrative API endpoints should be mandatory, along with regular security audits of API access logs to identify potential exploitation attempts. Organizations should also consider implementing multi-factor authentication for administrative access and establishing network segmentation to limit the potential impact of a successful exploitation. The vulnerability demonstrates the critical importance of validating request origins and implementing proper session management in web applications and API interfaces, as outlined in OWASP Top Ten Project recommendations for secure API development and the NIST Cybersecurity Framework's principles for protecting against unauthorized access and privilege escalation attacks.