CVE-2011-4247 in RealPlayer
Summary
by MITRE
RealNetworks RealPlayer before 15.0.0 allows remote attackers to execute arbitrary code via a crafted QCELP stream.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 11/26/2021
The vulnerability identified as CVE-2011-4247 represents a critical remote code execution flaw within RealNetworks RealPlayer software versions prior to 15.0.0. This security weakness specifically targets the media player's handling of QCELP (Quarter-Cycle Code Excited Linear Prediction) audio streams, which are commonly used in mobile communications and multimedia applications. The vulnerability arises from insufficient input validation and memory management within the player's multimedia processing components, creating an exploitable condition that can be triggered through maliciously crafted media content. The QCELP format, while designed for efficient voice compression in mobile environments, becomes a vector for privilege escalation when processed by vulnerable RealPlayer installations.
The technical implementation of this vulnerability stems from buffer overflow conditions that occur during the parsing of malformed QCELP streams. When RealPlayer attempts to decode and render these specially crafted audio packets, the software fails to properly validate the stream parameters and boundaries, leading to memory corruption that can be leveraged by attackers to inject and execute arbitrary code within the context of the running application. This flaw operates at the intersection of multimedia processing and memory safety, where the player's decoder does not adequately sanitize incoming data before processing it in memory. The vulnerability is classified under CWE-121 as a stack-based buffer overflow, which allows attackers to overwrite adjacent memory locations and potentially redirect program execution flow. The attack surface is particularly concerning as it requires no user interaction beyond opening the malicious stream, making it a prime candidate for automated exploitation.
The operational impact of CVE-2011-4247 extends beyond simple remote code execution to encompass potential system compromise and privilege escalation. Successful exploitation can enable attackers to gain full control over affected systems, potentially leading to data theft, system monitoring, or deployment of additional malware. The vulnerability affects a wide range of Windows operating systems and can be exploited through various delivery mechanisms including email attachments, web downloads, or malicious websites. Organizations running vulnerable RealPlayer versions face significant risk as the flaw can be exploited without user awareness, making it particularly dangerous in enterprise environments where media playback is common. The attack pattern aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as attackers can leverage the executed code to establish persistence and maintain access to compromised systems. Network-based exploitation is particularly concerning since the vulnerability can be triggered through web-based media delivery, allowing attackers to compromise systems remotely without physical access.
Mitigation strategies for CVE-2011-4247 primarily focus on immediate software updates and system hardening measures. The most effective solution involves upgrading to RealPlayer version 15.0.0 or later, which includes patched memory handling and input validation routines that prevent the buffer overflow conditions. Organizations should implement network segmentation to limit access to media playback applications and consider disabling RealPlayer in environments where it is not essential. Additional protective measures include deploying intrusion detection systems that can identify suspicious QCELP stream patterns and implementing application whitelisting policies to restrict execution of untrusted media players. Security administrators should also consider network-based filtering to block known malicious QCELP content and monitor for anomalous media processing activities. The vulnerability highlights the importance of regular security patch management and demonstrates how multimedia processing components can become attack vectors when proper input validation is not implemented. Organizations should conduct vulnerability assessments to identify all systems running vulnerable RealPlayer versions and prioritize remediation based on risk exposure.