CVE-2008-5911 in Helix Server
Summary
by MITRE
Multiple buffer overflows in RealNetworks Helix Server and Helix Mobile Server 11.x before 11.1.8 and 12.x before 12.0.1 allow remote attackers to (1) cause a denial of service via three crafted RTSP SETUP commands, or execute arbitrary code via (2) an NTLM authentication request with malformed base64-encoded data, (3) an RTSP DESCRIBE command, or (4) a DataConvertBuffer request.
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Analysis
by VulDB Data Team • 08/04/2021
The vulnerability identified as CVE-2008-5911 represents a critical security flaw affecting RealNetworks Helix Server and Helix Mobile Server versions 11.x prior to 11.1.8 and 12.x prior to 12.0.1. This vulnerability manifests through multiple buffer overflow conditions that can be exploited remotely, creating significant risks for organizations relying on these media streaming servers. The flaw resides in the handling of various RTSP (Real Time Streaming Protocol) commands and authentication mechanisms, making it particularly dangerous as it can be triggered through normal network operations.
The technical implementation of this vulnerability involves four distinct attack vectors that all stem from improper input validation and memory management within the server software. The first vector allows for denial of service through three crafted RTSP SETUP commands, while the second vector enables arbitrary code execution via NTLM authentication requests containing malformed base64-encoded data. The third vector targets RTSP DESCRIBE commands, and the fourth involves DataConvertBuffer requests. These buffer overflows occur when the server fails to properly validate the length of incoming data before copying it into fixed-size memory buffers, creating opportunities for attackers to overwrite adjacent memory locations and potentially execute malicious code.
From an operational impact perspective, this vulnerability creates multiple attack surfaces that can be leveraged by remote attackers without requiring authentication for certain vectors. The denial of service aspect can disrupt media streaming services, potentially affecting thousands of users simultaneously, while the arbitrary code execution capabilities allow attackers to gain full control over affected servers. This vulnerability directly impacts the availability, integrity, and confidentiality of streaming services, as compromised servers can be used to serve malicious content, redirect traffic, or provide backdoor access to internal networks. The attack vectors span across different protocol implementations, making comprehensive protection challenging and requiring careful monitoring of all RTSP interactions.
The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and CWE-122, which covers heap-based buffer overflow scenarios. Additionally, this vulnerability maps to several ATT&CK tactics including TA0001 (Initial Access) through network service exploitation, TA0002 (Execution) via arbitrary code execution, and TA0005 (Defense Evasion) through potential use of compromised servers for further attacks. Organizations should implement immediate mitigation strategies including applying the vendor-provided patches, implementing network segmentation to limit access to streaming services, and monitoring for suspicious RTSP traffic patterns. The vulnerability also highlights the importance of proper input validation and memory management practices in network services, emphasizing the need for regular security assessments and vulnerability management programs to prevent similar issues in other software components.