CVE-2008-5243 in xine-lib
Summary
by MITRE
The real_parse_headers function in demux_real.c in xine-lib 1.1.12, and other 1.1.15 and earlier versions, relies on an untrusted input length value to "reindex into an allocated buffer," which allows remote attackers to cause a denial of service (crash) via a crafted value, probably an array index error.
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Analysis
by VulDB Data Team • 08/24/2019
The vulnerability identified as CVE-2008-5243 resides within the xine-lib multimedia library version 1.1.12 and earlier, specifically in the real_parse_headers function located in the demux_real.c file. This flaw represents a classic buffer over-read condition that occurs when processing RealMedia file formats, making it particularly dangerous in multimedia applications that handle untrusted input from network sources. The vulnerability stems from the library's improper handling of input validation during the parsing of RealMedia container headers, where the software trusts the length field provided in the media file without adequate bounds checking.
The technical implementation of this vulnerability involves a critical flaw in input sanitization where the real_parse_headers function directly uses an untrusted length value to calculate buffer indices for memory allocation and subsequent data reindexing operations. When an attacker crafts a malicious RealMedia file with an oversized or malformed length field, the function attempts to allocate memory or access buffer locations that exceed the allocated boundaries. This leads to undefined behavior and typically results in memory corruption that manifests as a segmentation fault or access violation, causing the application to crash and potentially leading to a denial of service condition. The vulnerability operates at the intersection of improper input validation and memory management, aligning with CWE-129, which addresses insufficient validation of length fields, and CWE-125, which covers out-of-bounds read conditions.
From an operational impact perspective, this vulnerability presents a significant threat to multimedia applications and systems that utilize xine-lib for media playback, particularly those exposed to untrusted network sources or user-uploaded content. The remote attack vector means that an attacker can exploit this flaw without requiring local access to the target system, making it particularly dangerous in web applications, media streaming services, or any environment where users can upload or access media files from external sources. The crash resulting from this vulnerability can be leveraged to deny service to legitimate users, potentially allowing for extended downtime of multimedia applications or services that depend on xine-lib functionality. Additionally, in some scenarios, this type of memory corruption could potentially be exploited to execute arbitrary code, although the primary impact documented is denial of service.
The mitigation strategies for CVE-2008-5243 focus on immediate patching of the affected xine-lib versions to the patched releases that implement proper input validation and bounds checking for length fields in media header parsing. System administrators should prioritize updating all affected applications that depend on xine-lib, particularly those handling network-based media streams or user-uploaded content. Additional defensive measures include implementing network segmentation to limit exposure of vulnerable applications to untrusted sources, deploying input validation at network boundaries, and utilizing application-level sandboxing techniques to contain potential exploitation attempts. Organizations should also consider implementing monitoring for abnormal application crashes or memory access patterns that could indicate exploitation attempts. The vulnerability demonstrates the importance of input validation in multimedia libraries and underscores the need for proper bounds checking in all memory operations, particularly in code handling untrusted data from network sources. This flaw aligns with ATT&CK technique T1203, which covers exploitation for privilege escalation through denial of service attacks, and highlights the broader category of memory safety issues that continue to affect multimedia and media processing libraries in modern computing environments.