CVE-2017-15922 in Libextractor
Summary
by MITRE
In GNU Libextractor 1.4, there is an out-of-bounds read in the EXTRACTOR_dvi_extract_method function in plugins/dvi_extractor.c.
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Analysis
by VulDB Data Team • 01/04/2023
The vulnerability identified as CVE-2017-15922 represents a critical out-of-bounds read flaw within GNU Libextractor version 1.4, specifically within the EXTRACTOR_dvi_extract_method function located in the plugins/dvi_extractor.c file. This issue manifests as a memory access violation that occurs when processing DVI (Device Independent) formatted files, which are commonly used for document preparation and typesetting in academic and professional environments. The flaw stems from inadequate input validation and boundary checking within the DVI file parsing logic, creating a scenario where the application attempts to read memory locations beyond the allocated buffer boundaries.
The technical implementation of this vulnerability involves the DVI extractor component failing to properly validate the length and structure of DVI file headers before attempting to parse their contents. When a maliciously crafted DVI file is processed, the function does not adequately check array bounds or buffer limits, allowing an attacker to manipulate the parsing routine into accessing memory regions that do not belong to the intended data structure. This particular flaw aligns with CWE-129, which specifically addresses insufficient validation of length of input buffers, and represents a classic example of improper input validation that can lead to information disclosure or potential remote code execution depending on the execution environment. The vulnerability operates at the application layer within the file processing pipeline, making it particularly dangerous when integrated into content management systems, document repositories, or any application that relies on Libextractor for metadata extraction from document files.
The operational impact of CVE-2017-15922 extends beyond simple memory corruption, as it can potentially enable attackers to extract sensitive information from memory segments that contain overlapping data or to cause application crashes that result in denial of service conditions. In environments where GNU Libextractor is used for automated document processing, such as email servers, web applications, or document management platforms, this vulnerability could be exploited to gain unauthorized access to system information or to disrupt service availability. The ATT&CK framework categorizes this type of vulnerability under T1059.007 for command and scripting interpreter, as exploitation may involve crafting malicious DVI files that trigger the vulnerable code path during normal file processing operations. The vulnerability's exploitation potential is further amplified when considering that DVI files are commonly encountered in academic and research environments where document processing systems may automatically analyze and extract metadata from uploaded files without proper sanitization.
Mitigation strategies for CVE-2017-15922 should focus on immediate patching of the GNU Libextractor component to version 1.6 or later, which contains the necessary boundary checking fixes. Organizations should implement input validation measures that enforce strict file format compliance before processing any DVI content, particularly in automated environments where file uploads are accepted from untrusted sources. Additionally, deployment of network segmentation and file type filtering mechanisms can help prevent malicious DVI files from reaching systems that utilize the vulnerable library. Security monitoring should include detection of unusual memory access patterns or application crashes that may indicate exploitation attempts, while regular vulnerability assessments should verify that all instances of GNU Libextractor within the environment have been properly updated. System administrators should also consider implementing sandboxing techniques for document processing operations to limit the potential impact of any successful exploitation attempts, ensuring that even if the vulnerability is exploited, the attacker's capabilities remain constrained to prevent broader system compromise.