CVE-2014-4071 in Lync
Summary
by MITRE
The Server in Microsoft Lync Server 2013 allows remote attackers to cause a denial of service (NULL pointer dereference and daemon hang) via a crafted request, aka "Lync Denial of Service Vulnerability."
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Analysis
by VulDB Data Team • 02/15/2022
The vulnerability identified as CVE-2014-4071 represents a critical denial of service weakness within Microsoft Lync Server 2013 that enables remote attackers to disrupt service availability through carefully constructed malicious requests. This vulnerability specifically targets the server component of the Lync platform, which serves as the core infrastructure for unified communications including instant messaging, presence information, voice over IP, and video conferencing services. The flaw manifests as a NULL pointer dereference condition that occurs when the server processes malformed or crafted requests, leading to daemon hang conditions that effectively render the communication services unavailable to legitimate users.
The technical nature of this vulnerability falls under CWE-476 which categorizes NULL pointer dereferences as a common programming error where software attempts to access memory through a null pointer reference. In the context of Lync Server 2013, this occurs when the server application fails to properly validate incoming requests before attempting to process them, allowing attackers to send specially crafted packets that trigger the NULL pointer dereference. The daemon hang condition represents a secondary effect where the server process becomes unresponsive and unable to handle additional legitimate requests, creating a cascading denial of service scenario that impacts all users relying on the unified communications platform. This vulnerability operates at the application layer and can be exploited without requiring authentication, making it particularly dangerous as it allows anyone on the network to potentially disrupt critical business communications.
The operational impact of CVE-2014-4071 extends beyond simple service disruption to potentially severe business continuity issues for organizations relying on Microsoft Lync for their communication infrastructure. When the server daemon hangs due to this vulnerability, it affects not only the immediate availability of instant messaging and presence services but also impacts voice and video conferencing capabilities that many enterprises depend upon for daily operations. The vulnerability's remote exploitability means that attackers can target the service from external networks, potentially causing widespread disruption across geographically distributed organizations. Organizations using Lync Server 2013 without proper network segmentation or monitoring may experience complete communication paralysis, affecting collaboration between teams, customer service operations, and critical business processes that depend on real-time communication services. The impact is particularly severe in enterprise environments where unified communications are integral to business operations and where the server may be handling thousands of concurrent users and communication sessions.
Mitigation strategies for CVE-2014-4071 should include immediate application of Microsoft security patches released in the April 2014 security updates, which specifically addressed this vulnerability through proper input validation and error handling mechanisms. Network segmentation and firewall rules should be implemented to restrict access to Lync Server 2013 to only trusted internal networks and specific authorized endpoints, reducing the attack surface available to potential remote attackers. Implementing intrusion detection systems with signature-based detection for known malicious request patterns can help identify exploitation attempts before they cause service disruption. Regular monitoring of server logs and system performance metrics should be established to quickly identify anomalous behavior that may indicate exploitation attempts. Additionally, organizations should consider implementing application-level firewalls or web application firewalls that can filter out malformed requests before they reach the Lync server components. The vulnerability's classification under the ATT&CK framework would place it within the privilege escalation and denial of service tactics, with specific relevance to the server-side application exploitation techniques that leverage memory corruption vulnerabilities to disrupt service availability. Organizations should also conduct regular vulnerability assessments and penetration testing to identify similar weaknesses in their communication infrastructure that could potentially be exploited in similar fashion.