CVE-2008-5247 in xine-lib
Summary
by MITRE
The real_parse_audio_specific_data function in demux_real.c in xine-lib 1.1.12, and other 1.1.15 and earlier versions, uses an untrusted height (aka codec_data_length) value as a divisor, which allow remote attackers to cause a denial of service (divide-by-zero error and crash) via a zero value.
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Analysis
by VulDB Data Team • 08/26/2019
The vulnerability identified as CVE-2008-5247 represents a critical divide-by-zero error in the xine-lib multimedia library version 1.1.12 and earlier, including 1.1.15. This flaw exists within the real_parse_audio_specific_data function located in the demux_real.c file, which is responsible for parsing audio-specific data from RealMedia format files. The issue arises from improper input validation where the function directly utilizes an untrusted height parameter, referred to as codec_data_length, without adequate sanitization or bounds checking. When a maliciously crafted RealMedia file contains a zero value for this parameter, the function attempts to perform a division operation using this zero value as a divisor, leading to an immediate system crash.
The technical implementation of this vulnerability demonstrates a classic case of improper input validation and exception handling within multimedia parsing libraries. The real_parse_audio_specific_data function processes codec-specific information embedded within RealMedia container files, where the codec_data_length field typically indicates the size of additional codec configuration data. However, the code fails to validate that this value is non-zero before using it in arithmetic operations, creating a condition where a divide-by-zero exception occurs. This type of error falls under CWE-369, which specifically addresses the use of a divide operation with a zero divisor, and represents a fundamental flaw in defensive programming practices. The vulnerability can be exploited through a specially crafted RealMedia file that contains a zero value in the codec_data_length field, making it particularly dangerous in environments where users might encounter untrusted media content.
The operational impact of CVE-2008-5247 extends beyond simple denial of service, as it can be leveraged by remote attackers to disrupt multimedia applications that rely on xine-lib for content playback. When exploited, the vulnerability causes immediate application crashes, potentially leading to system instability or complete application termination. This makes it particularly concerning for media servers, web browsers, and multimedia applications that process user-uploaded content or stream media from untrusted sources. The vulnerability affects not just individual user systems but also broader network services that depend on xine-lib for media processing, as a single malicious file could potentially bring down entire media processing pipelines. The exploit requires minimal privileges and can be executed remotely, making it a significant concern for web applications and services that handle multimedia content.
Mitigation strategies for CVE-2008-5247 should focus on immediate patching and input validation improvements. The most effective solution involves upgrading to xine-lib version 1.1.16 or later, where the vulnerability has been addressed through proper input validation and error handling. System administrators should also implement strict input validation at multiple layers, ensuring that all codec data parameters are checked for zero values before arithmetic operations are performed. Network-level protections can include content filtering systems that scan media files for suspicious patterns in codec data fields, particularly those that might indicate malformed RealMedia files. The implementation of defensive programming practices, including explicit zero checks before division operations and proper exception handling, should be enforced throughout multimedia processing libraries. Organizations should also consider implementing sandboxing mechanisms for media processing applications to limit the impact of potential exploitation attempts, aligning with ATT&CK technique T1203 for process injection and T1059 for command and scripting interface. Additionally, regular security audits of multimedia libraries and applications should be conducted to identify similar vulnerabilities in other components of the media processing stack.