CVE-2009-2533 in Helix Server
Summary
by MITRE
rmserver in RealNetworks Helix Server and Helix Mobile Server before 13.0.0 allows remote attackers to cause a denial of service (daemon exit) via multiple RTSP SET_PARAMETER requests with empty DataConvertBuffer headers.
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Analysis
by VulDB Data Team • 12/07/2024
The vulnerability identified as CVE-2009-2533 affects RealNetworks Helix Server and Helix Mobile Server versions prior to 13.0.0, specifically within the rmserver component that handles RTSP protocol communications. This issue represents a denial of service vulnerability that can be exploited remotely by attackers who send specially crafted RTSP SET_PARAMETER requests containing empty DataConvertBuffer headers. The flaw demonstrates characteristics consistent with CWE-119 Improper Restriction of Operations within a Limited Access Point, as the server fails to properly validate incoming request parameters before processing them, leading to unexpected daemon termination.
The technical exploitation of this vulnerability occurs through the RTSP protocol which is commonly used for controlling multimedia streaming servers. When multiple RTSP SET_PARAMETER requests are sent with empty DataConvertBuffer headers, the rmserver process encounters a condition that causes it to exit unexpectedly, resulting in a complete denial of service for the streaming service. This behavior aligns with ATT&CK technique T1499.004 Network Denial of Service, as the attacker can disrupt legitimate service availability without requiring authentication or elevated privileges. The vulnerability stems from inadequate input validation and error handling within the server's RTSP implementation, where the system does not properly sanitize or validate the DataConvertBuffer header values before attempting to process them.
The operational impact of this vulnerability extends beyond simple service disruption as it affects the reliability and availability of multimedia streaming services that depend on RealNetworks Helix Server infrastructure. Organizations utilizing these server versions may experience unexpected service outages, potentially affecting content delivery to end users and resulting in business disruption. The vulnerability is particularly concerning because it requires minimal effort to exploit, as attackers only need to send multiple RTSP requests with malformed headers rather than possessing advanced technical skills or specific access privileges. This makes the vulnerability attractive to malicious actors seeking to disrupt services without significant resources or expertise.
Mitigation strategies for CVE-2009-2533 should focus on immediate patching of affected systems to version 13.0.0 or later, which contains the necessary fixes for proper header validation. Network administrators should implement RTSP traffic filtering at firewalls and intrusion detection systems to monitor for suspicious patterns of SET_PARAMETER requests with empty headers. Additionally, configuring the server to limit the rate of incoming RTSP requests and implementing proper logging mechanisms can help detect and prevent exploitation attempts. The vulnerability highlights the importance of proper input validation in network services and demonstrates how seemingly minor implementation flaws can result in significant service disruption, emphasizing the need for comprehensive security testing and validation of network protocols in streaming server implementations.