CVE-2019-15531 in Libextractor
Summary
by MITRE
GNU Libextractor through 1.9 has a heap-based buffer over-read in the function EXTRACTOR_dvi_extract_method in plugins/dvi_extractor.c.
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Analysis
by VulDB Data Team • 12/01/2023
The vulnerability identified as CVE-2019-15531 represents a critical heap-based buffer over-read flaw within GNU Libextractor version 1.9 and earlier. This issue resides in the EXTRACTOR_dvi_extract_method function located within the plugins/dvi_extractor.c source file, making it a significant security concern for systems that utilize this library for document metadata extraction. The flaw manifests when processing DVI (Device Independent) formatted documents, which are commonly used in typesetting and publishing environments. The buffer over-read occurs when the library attempts to read data from memory locations beyond the allocated buffer boundaries, potentially exposing sensitive information or enabling further exploitation.
From a technical perspective, this vulnerability stems from inadequate input validation and boundary checking within the DVI extraction plugin. The EXTRACTOR_dvi_extract_method function fails to properly verify the size of incoming DVI data structures before attempting to parse them, leading to memory access violations that can result in information disclosure or system instability. The heap-based nature of the over-read indicates that the vulnerable code operates on dynamically allocated memory segments, making the exploitation more complex but potentially more impactful than stack-based buffer overflows. This type of vulnerability falls under CWE-125, which specifically addresses "Out-of-bounds Read" conditions in software systems. The flaw demonstrates poor memory management practices and highlights the importance of robust input sanitization in security-critical libraries.
The operational impact of CVE-2019-15531 extends beyond simple data corruption, as it can potentially enable attackers to extract sensitive information from memory segments adjacent to the targeted buffer. Systems utilizing GNU Libextractor for processing DVI documents, particularly those handling untrusted input from external sources, become vulnerable to information disclosure attacks. This vulnerability is particularly concerning in environments where metadata extraction is performed on documents received from unknown or untrusted parties, such as email attachments, file sharing platforms, or content management systems. The attack surface is broadened by the library's widespread use in various applications and services that require document metadata processing capabilities. The vulnerability aligns with ATT&CK technique T1059.007, which covers "Command and Scripting Interpreter: PowerShell," as attackers could potentially leverage information disclosure to gain insights into system memory structures and application behavior. Additionally, the vulnerability could facilitate more sophisticated attacks by providing attackers with memory layout information that could be used to bypass security mechanisms or exploit other related vulnerabilities.
Mitigation strategies for CVE-2019-15531 should prioritize immediate patching of affected systems with GNU Libextractor version 1.10 or later, which contains the necessary fixes for the buffer over-read condition. Organizations should implement comprehensive input validation measures for all document processing pipelines, particularly those involving DVI files, and consider deploying additional security controls such as sandboxing or memory protection mechanisms. Network administrators should monitor for potential exploitation attempts targeting this vulnerability, particularly in systems that process external document uploads. The fix implemented in the patched versions typically involves proper bounds checking and memory allocation validation within the DVI extraction plugin, ensuring that all buffer operations remain within allocated memory boundaries. Security teams should also conduct thorough vulnerability assessments to identify all systems utilizing affected versions of GNU Libextractor and prioritize remediation efforts based on risk exposure and system criticality. Regular security updates and patch management procedures should be reinforced to prevent similar vulnerabilities from arising in the future, emphasizing the importance of thorough code review processes and automated security testing.