CVE-2017-15267 in Libextractor
Summary
by MITRE
In GNU Libextractor 1.4, there is a NULL Pointer Dereference in flac_metadata in flac_extractor.c.
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Analysis
by VulDB Data Team • 01/03/2023
The vulnerability CVE-2017-15267 represents a critical null pointer dereference flaw within GNU Libextractor version 1.4, specifically within the flac_metadata function located in the flac_extractor.c source file. This issue arises during the processing of FLAC audio files when the library attempts to extract metadata from these files. The flaw occurs when the application encounters certain malformed or specially crafted FLAC files that trigger unexpected behavior in the metadata extraction routine. The vulnerability is classified under CWE-476 as a NULL pointer dereference, which represents a fundamental programming error where an application attempts to access memory through a pointer that has not been properly initialized or has been set to NULL. This type of vulnerability typically results in application crashes or can potentially be exploited to achieve more severe consequences such as arbitrary code execution or denial of service attacks.
The technical implementation of this vulnerability stems from insufficient input validation and error handling within the FLAC metadata processing code. When the flac_metadata function processes audio files, it fails to properly validate the structure and content of the FLAC file headers and metadata blocks. The function likely assumes certain data structures will exist in memory but encounters NULL pointers where valid data should be present, leading to the dereference operation that causes the application to crash. This behavior can be triggered by malformed FLAC files that contain unexpected or corrupted metadata fields, or files that manipulate the FLAC file format in ways that the library's parser does not anticipate. The vulnerability specifically affects the extraction process where the library attempts to parse and extract information from the file's metadata, making it particularly dangerous in environments where automated file processing occurs.
The operational impact of CVE-2017-15267 extends beyond simple application crashes, as it can be leveraged to create denial of service conditions within systems that rely on GNU Libextractor for file metadata processing. This vulnerability affects software applications that utilize the library for automatic file scanning, media library management, or content indexing operations. Attackers could potentially exploit this vulnerability by uploading or providing specially crafted FLAC files to systems that process audio metadata automatically, causing the target applications to crash and become unavailable to legitimate users. The vulnerability is particularly concerning in server environments, content management systems, or media processing pipelines where automated file handling occurs without proper input sanitization. The flaw can be exploited through various attack vectors including web applications that accept file uploads, media servers that automatically scan directories for audio files, or any system that integrates GNU Libextractor for metadata extraction purposes.
Mitigation strategies for CVE-2017-15267 should focus on immediate software updates and input validation improvements. The most effective remediation involves upgrading to GNU Libextractor version 1.5 or later, where the null pointer dereference has been addressed through proper error handling and input validation mechanisms. System administrators should implement comprehensive patch management procedures to ensure all affected systems receive the necessary updates promptly. Additionally, organizations should consider implementing input sanitization measures that validate FLAC file structures before processing, including checks for malformed headers and unexpected metadata content. The vulnerability aligns with ATT&CK technique T1203 by enabling denial of service attacks through application instability, and can be categorized under the broader ATT&CK tactic of Execution by potentially allowing for more sophisticated exploitation attempts. Organizations should also consider implementing network segmentation and monitoring to detect unusual file processing patterns that might indicate exploitation attempts. The fix implemented in later versions typically includes proper null pointer checks and robust error handling that prevents the application from crashing when encountering malformed input data, thereby improving overall system stability and security posture.