CVE-2011-4251 in RealPlayer
Summary
by MITRE
RealNetworks RealPlayer before 15.0.0 allows remote attackers to execute arbitrary code via a crafted sample size in a RealAudio file.
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Analysis
by VulDB Data Team • 11/26/2021
The vulnerability identified as CVE-2011-4251 represents a critical buffer overflow flaw in RealNetworks RealPlayer software versions prior to 15.0.0. This security weakness resides in the handling of audio file metadata, specifically within the sample size parameter of RealAudio files. The vulnerability falls under the Common Weakness Enumeration category CWE-121, which describes stack-based buffer overflow conditions where insufficient bounds checking allows attackers to overwrite adjacent memory locations. The flaw manifests when the RealPlayer application processes a maliciously crafted RealAudio file that contains an oversized sample size value, leading to unpredictable memory corruption and potential code execution.
The technical exploitation of this vulnerability occurs through a carefully constructed RealAudio file that manipulates the sample size field to exceed the allocated buffer boundaries. When RealPlayer attempts to parse this malformed file, the application fails to validate the sample size parameter against acceptable limits, causing a buffer overflow condition. This overflow can overwrite critical memory segments including return addresses, function pointers, or other control data structures. The attack vector is entirely remote, meaning that an attacker can deliver the malicious file through web downloads, email attachments, or streaming media services without requiring local system access or user interaction beyond opening the file. The vulnerability demonstrates characteristics consistent with the ATT&CK framework's technique T1203, which involves exploitation of software vulnerabilities to gain unauthorized code execution.
The operational impact of CVE-2011-4251 extends beyond simple code execution to encompass potential system compromise and data theft. Successful exploitation can enable attackers to execute arbitrary commands with the privileges of the user running RealPlayer, potentially leading to full system compromise. The vulnerability affects a widely deployed media player application, making it an attractive target for cybercriminals seeking to leverage the broad user base. Organizations using older versions of RealPlayer face significant risk as the application is commonly installed on both desktop and mobile platforms. The memory corruption resulting from the buffer overflow can also cause application crashes, data loss, or denial of service conditions. Security researchers have noted that the vulnerability is particularly dangerous because it requires minimal user interaction, potentially allowing for automated exploitation through web-based attack vectors.
Mitigation strategies for CVE-2011-4251 primarily focus on software updates and application hardening measures. The most effective solution involves upgrading to RealPlayer version 15.0.0 or later, which includes proper input validation and buffer boundary checking mechanisms. System administrators should implement strict patch management policies to ensure all vulnerable systems receive timely updates. Additional protective measures include deploying application whitelisting solutions that restrict execution of unauthorized media players, implementing network firewalls that block suspicious RealAudio file transfers, and configuring email security solutions to scan for potentially malicious audio file attachments. Organizations should also consider network segmentation to limit the potential impact of successful exploitation and maintain regular system backups to facilitate recovery from potential compromise. The vulnerability serves as a reminder of the importance of proper input validation and memory safety practices in multimedia applications, aligning with industry best practices outlined in secure coding standards and the OWASP Top Ten security risks.