CVE-2016-6276 in Linux Virtual Delivery Agent
Summary
by MITRE
Citrix Linux Virtual Delivery Agent (aka VDA, formerly Linux Virtual Desktop) before 1.4.0 allows local users to gain root privileges via unspecified vectors.
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Analysis
by VulDB Data Team • 04/26/2019
The Citrix Linux Virtual Delivery Agent represents a critical security vulnerability identified as CVE-2016-6276, affecting versions prior to 1.4.0 of the Linux Virtual Desktop component. This vulnerability resides within the Linux Virtual Delivery Agent implementation which serves as a key component in Citrix's virtual desktop infrastructure, enabling remote desktop services for Linux-based environments. The flaw manifests as a local privilege escalation vulnerability that permits unauthorized local users to elevate their privileges to the root level, fundamentally compromising system security and integrity.
The technical nature of this vulnerability stems from unspecified vectors within the VDA implementation that create opportunities for privilege escalation. According to CWE classification, this vulnerability aligns with CWE-269, which addresses privilege escalation through improper access control mechanisms. The flaw likely involves inadequate input validation, improper privilege handling, or flawed permission models within the Linux VDA service components. Attackers exploiting this vulnerability can leverage local access to manipulate system processes or files that should normally be restricted to root-level operations, effectively bypassing normal security boundaries that protect against unauthorized administrative access.
The operational impact of this vulnerability extends beyond simple privilege escalation, creating significant risks for enterprise environments utilizing Citrix virtual desktop solutions. Organizations deploying affected Linux VDA versions face potential system compromise, data breaches, and unauthorized access to sensitive corporate resources. The vulnerability affects the core security model of the virtual desktop infrastructure, as local attackers can exploit this flaw to gain complete administrative control over affected systems. This creates cascading security risks where compromised individual desktops can serve as entry points for broader network infiltration, particularly in environments where the VDA is used for remote access to corporate networks. The vulnerability's local nature means it can be exploited without requiring network exposure, making it particularly dangerous in environments with limited network segmentation.
Mitigation strategies for CVE-2016-6276 primarily focus on immediate patch deployment to upgrade affected Linux VDA installations to version 1.4.0 or later, which contains the necessary security fixes. System administrators should conduct comprehensive inventory assessments to identify all affected Linux VDA installations across their enterprise environment. Additionally, implementing proper access controls and privilege management practices can help reduce the attack surface, though these measures do not fully compensate for the underlying vulnerability. Network segmentation and monitoring solutions should be enhanced to detect unusual privilege escalation activities that might indicate exploitation attempts. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation techniques and can be classified under T1068, which covers local privilege escalation through various system-level attacks. Organizations should also consider implementing comprehensive endpoint detection and response capabilities to monitor for suspicious activities that might indicate exploitation of this vulnerability.