CVE-2019-8905 in libmagic
Summary
by MITRE
do_core_note in readelf.c in libmagic.a in file 5.35 has a stack-based buffer over-read, related to file_printable, a different vulnerability than CVE-2018-10360.
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Analysis
by VulDB Data Team • 07/11/2023
The vulnerability identified as CVE-2019-8905 represents a critical stack-based buffer over-read flaw within the file command utility version 5.35. This issue resides in the do_core_note function located in readelf.c within the libmagic.a library component. The vulnerability manifests when processing certain malformed or crafted input files, specifically those that trigger the file_printable function during magic file analysis. Unlike CVE-2018-10360 which addressed a different aspect of the same codebase, this vulnerability specifically targets memory access patterns that can lead to information disclosure or potential code execution. The flaw occurs because the application fails to properly validate input boundaries when processing core dump notes, allowing an attacker to read beyond allocated memory buffers. This type of vulnerability falls under CWE-121 Stack-based Buffer Overflow and can be classified as a memory safety issue within the context of the ATT&CK framework under the technique of Memory Exhaustion and Code Injection. The file command utility is widely used for identifying file types and is often invoked in automated systems, making this vulnerability particularly dangerous when exploited in automated environments.
The technical implementation of this vulnerability involves the manipulation of input data structures that the file command processes to determine file characteristics. When the do_core_note function encounters a specially crafted input, it attempts to read memory locations beyond the intended buffer boundaries. This over-read can expose sensitive data from adjacent memory locations including stack contents, heap data, or other program variables. The file_printable function serves as the trigger point where the buffer over-read occurs, making it a critical component in the exploitation chain. The vulnerability is particularly concerning because it operates within a utility that is commonly used in security contexts, system administration, and automated file processing pipelines. Attackers can potentially leverage this flaw to extract information from memory that might include authentication tokens, cryptographic keys, or other sensitive system information. The exploitation requires careful crafting of input files that can trigger the specific execution path leading to the buffer over-read condition.
The operational impact of CVE-2019-8905 extends beyond simple information disclosure, as it can potentially enable more sophisticated attacks when combined with other vulnerabilities or in specific environmental conditions. Systems that rely on the file command for automated file type detection, malware analysis, or content filtering are at risk when processing untrusted input. The vulnerability can be exploited through various attack vectors including email attachments, file uploads, or automated scanning of file systems. In security-sensitive environments such as intrusion detection systems, malware analysis sandboxes, or automated compliance checking systems, this vulnerability could provide attackers with a means to extract confidential information or establish persistence. The potential for remote code execution increases when this vulnerability is combined with other memory corruption issues or when the target system has additional weaknesses. Organizations using file command versions containing this vulnerability should consider it as a high-priority threat that could compromise system integrity and confidentiality. The vulnerability's exploitation requires minimal privileges and can be automated, making it particularly dangerous in environments where untrusted files are routinely processed.
Mitigation strategies for CVE-2019-8905 should focus on immediate patching of the affected file command utility to version 5.36 or later, which contains the necessary fixes for the buffer over-read condition. Organizations should implement input validation and sanitization measures for any systems that process untrusted file content, particularly those using the file command or similar magic-based file identification utilities. Network segmentation and access controls should be strengthened to limit the potential impact of exploitation, especially in automated environments where file processing occurs without human intervention. Regular security assessments should be conducted to identify systems running vulnerable versions of the file command utility, with particular attention to systems that process external file uploads or automated file analysis workflows. The implementation of sandboxing techniques for file processing and the deployment of intrusion detection systems that can monitor for exploitation attempts are recommended defensive measures. Additionally, organizations should consider implementing automated patch management processes to ensure timely updates of security-critical utilities like the file command. The vulnerability serves as a reminder of the importance of proper memory management in security-critical software components and highlights the need for continuous vulnerability assessment and remediation processes.