CVE-2013-4119 in FreeRDP
Summary
by MITRE
FreeRDP before 1.1.0-beta+2013071101 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) by disconnecting before authentication has finished.
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Analysis
by VulDB Data Team • 09/21/2022
The vulnerability identified as CVE-2013-4119 affects FreeRDP versions prior to 11.0-beta+2013071101 and represents a denial of service flaw that can be exploited by remote attackers through a specific connection sequence. This issue manifests when a client disconnects from the FreeRDP server before the authentication process has been completed, leading to a NULL pointer dereference that ultimately causes the application to crash. The vulnerability specifically targets the protocol handling mechanisms within FreeRDP's remote desktop implementation, where the software fails to properly validate connection states during the authentication handshake phase.
The technical root cause of this vulnerability stems from inadequate input validation and state management within the FreeRDP codebase. When a client initiates a connection and subsequently disconnects prematurely, the server-side code does not properly handle the NULL pointer reference that occurs during the authentication completion phase. This flaw falls under the category of improper error handling and memory management issues, which are commonly classified under CWE-476 in the Common Weakness Enumeration catalog. The vulnerability demonstrates a classic race condition scenario where the application attempts to access memory locations that have not been properly initialized or allocated, resulting in a segmentation fault or application crash.
From an operational perspective, this denial of service vulnerability presents significant risks for organizations relying on FreeRDP for remote desktop services. Attackers can exploit this weakness by simply initiating a connection to a FreeRDP server and immediately disconnecting before authentication completes, causing the service to become unavailable to legitimate users. The impact extends beyond simple service disruption as it can be used as a vector for broader attacks, potentially leading to service exhaustion or resource depletion. According to the MITRE ATT&CK framework, this vulnerability could be categorized under the T1499.004 technique for Network Denial of Service, where attackers leverage protocol implementation weaknesses to disrupt service availability.
The exploitation of this vulnerability requires minimal technical skill and can be accomplished through automated tools that simply establish connections and disconnect rapidly. This makes it particularly dangerous as it can be used in conjunction with other attack vectors to create more sophisticated denial of service campaigns. Organizations utilizing FreeRDP for remote access services should consider the broader implications of this vulnerability, as it could be part of a larger attack strategy targeting remote desktop infrastructure. The vulnerability also highlights the importance of proper state management in network protocols, particularly in environments where multiple concurrent connections are expected.
Mitigation strategies for CVE-2013-4119 primarily involve upgrading to FreeRDP version 1.1.0-beta+2013071101 or later, which includes proper handling of premature disconnections during authentication. System administrators should implement connection rate limiting and monitoring to detect unusual connection patterns that may indicate exploitation attempts. Network segmentation and access control measures can help reduce the attack surface by limiting exposure to the vulnerable FreeRDP service. Additionally, implementing proper logging and alerting mechanisms around connection establishment and authentication completion phases will aid in detecting potential exploitation attempts and provide forensic evidence for incident response activities.