CVE-2016-4810 in XenApp
Summary
by MITRE
Citrix Studio before 7.6.1000, Citrix XenDesktop 7.x before 7.6 LTSR Cumulative Update 1 (CU1), and Citrix XenApp 7.5 and 7.6 allow attackers to set Access Policy rules on the XenDesktop Delivery Controller via unspecified vectors.
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Analysis
by VulDB Data Team • 12/28/2018
Citrix Studio versions prior to 7.6.1000 and Citrix XenDesktop 7.x versions before 7.6 LTSR Cumulative Update 1 contain a critical access control vulnerability that allows remote attackers to manipulate Access Policy rules on XenDesktop Delivery Controllers through unspecified attack vectors. This vulnerability represents a significant security weakness in Citrix's enterprise virtualization and desktop delivery platform, affecting organizations that rely on proper access control mechanisms to protect their virtual desktop infrastructure. The flaw exists within the administrative interface and configuration management components of the Citrix portfolio, specifically impacting the authorization controls that govern who can modify critical policy settings.
The technical nature of this vulnerability stems from insufficient input validation and access control enforcement within the Citrix Studio administrative console and related management interfaces. Attackers can exploit this weakness to bypass normal authorization checks and directly manipulate Access Policy rules without proper authentication or privilege validation. This represents a privilege escalation vulnerability that operates at the administrative interface level, allowing unauthorized users to modify critical security policies that control access to virtual desktops and applications. The unspecified attack vectors suggest that multiple entry points or methods may exist for exploitation, potentially including web-based attacks, API manipulation, or other administrative interface vulnerabilities that could be leveraged to achieve this unauthorized policy modification.
The operational impact of this vulnerability is severe and far-reaching for organizations using affected Citrix products. Successful exploitation could enable attackers to weaken or completely bypass access controls that protect virtual desktop environments, potentially allowing unauthorized users to gain access to sensitive corporate resources, data, or applications. This vulnerability directly undermines the security posture of organizations that depend on Citrix XenDesktop and XenApp solutions for their virtual desktop infrastructure, as it allows attackers to modify the very policies that govern who can access what resources within their virtual environments. The implications extend beyond simple access control violations to potentially enable broader compromise of the entire virtual desktop infrastructure, as access policies often control critical aspects of user authentication, resource allocation, and security enforcement.
Organizations affected by this vulnerability should immediately implement the recommended mitigations including applying Citrix's official patches and updates to bring their systems up to version 7.6.1000 or later for Studio and 7.6 LTSR CU1 for XenDesktop. Security administrators should also conduct thorough reviews of existing access policies and monitor for unauthorized modifications to policy configurations. The vulnerability aligns with CWE-284, which describes improper access control issues, and represents a specific instance of privilege escalation where attackers can gain unauthorized administrative capabilities. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and can be leveraged as part of broader attack chains that may include initial access through other vectors followed by lateral movement and persistence within the virtual desktop environment. Organizations should also consider implementing additional monitoring and alerting mechanisms around policy changes to detect and respond to potential exploitation attempts.