CVE-2017-17440 in Libextractor
Summary
by MITRE
GNU Libextractor 1.6 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted GIF, IT (Impulse Tracker), NSFE, S3M (Scream Tracker 3), SID, or XM (eXtended Module) file, as demonstrated by the EXTRACTOR_xm_extract_method function in plugins/xm_extractor.c.
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Analysis
by VulDB Data Team • 01/17/2023
The vulnerability identified as CVE-2017-17440 affects GNU Libextractor version 1.6, a library designed to extract metadata from various file formats including audio files and graphics. This critical flaw manifests as a denial of service condition that can be triggered remotely through the careful crafting of specific file formats. The vulnerability specifically targets the EXTRACTOR_xm_extract_method function located within the plugins/xm_extractor.c file, which handles extraction processes for XM (eXtended Module) files, a format commonly used for music composition and tracking. The flaw represents a classic null pointer dereference issue that occurs when the application attempts to access memory through a pointer that has not been properly initialized or validated.
The technical implementation of this vulnerability stems from inadequate input validation within the metadata extraction routines of the affected library. When processing maliciously crafted files such as GIF images, IT (Impulse Tracker), NSFE, S3M (Scream Tracker 3), SID, or XM files, the library fails to properly handle edge cases or malformed data structures. The null pointer dereference occurs during the extraction process when the application attempts to access a memory location that has not been allocated or properly initialized, leading to an immediate application crash. This behavior aligns with CWE-476 which specifically addresses null pointer dereference vulnerabilities, and represents a fundamental failure in defensive programming practices. The vulnerability affects multiple file formats because they all pass through similar extraction pathways within the library's plugin architecture, making it a widespread issue across the supported file types.
From an operational perspective, this vulnerability presents a significant risk to systems that rely on GNU Libextractor for automated metadata processing or content analysis. Attackers can exploit this weakness by uploading or transmitting specially crafted files to systems that utilize the library, potentially causing service disruption and denial of access to legitimate users. The impact extends beyond simple service interruption as it can be leveraged in broader attack chains where multiple system components depend on metadata extraction capabilities. This vulnerability is particularly concerning in environments such as content management systems, digital asset repositories, or any platform that automatically processes user-uploaded files. The remote exploitation capability means that attackers do not need physical access to the target system and can trigger the vulnerability through network-based attacks, making it a high-severity threat according to industry standards. The ATT&CK framework categorizes this as a denial of service attack vector that can be used to disrupt system availability and potentially serve as a stepping stone for more complex attacks.
The mitigation strategies for this vulnerability require immediate patching of the GNU Libextractor library to version 1.7 or later, which contains the necessary fixes for the null pointer dereference issues. Organizations should also implement input validation controls at network boundaries and file processing points to filter out potentially malicious files before they reach the vulnerable library. Additional defensive measures include deploying sandboxing techniques for file analysis, implementing proper error handling and graceful degradation mechanisms, and establishing monitoring systems to detect unusual crash patterns or service disruptions. Security teams should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts, while maintaining regular vulnerability scanning to identify other potential weaknesses in the system's file processing pipelines. The fix addresses the root cause by ensuring proper null pointer checks and validation before memory access operations, aligning with secure coding practices recommended by both CWE guidelines and industry best practices for preventing similar vulnerabilities in software development.