CVE-2019-20009 in LibreDWG
Summary
by MITRE
An issue was discovered in GNU LibreDWG before 0.93. Crafted input will lead to an attempted excessive memory allocation in dwg_decode_SPLINE_private in dwg.spec.
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Analysis
by VulDB Data Team • 03/17/2024
The vulnerability identified as CVE-2019-20009 represents a critical memory allocation flaw within the GNU LibreDWG library version 0.93 and earlier. This issue manifests in the dwg_decode_SPLINE_private function located within the dwg.spec module, where maliciously crafted input data can trigger unintended memory allocation behavior. The flaw demonstrates characteristics consistent with memory corruption vulnerabilities that could potentially lead to system instability or unauthorized code execution. The vulnerability affects the decoding process of SPLINE entities within DWG files, which are commonly used in computer-aided design applications and document exchange formats.
The technical implementation of this vulnerability stems from inadequate input validation and memory management within the SPLINE decoding routine. When processing malformed DWG files containing specially crafted SPLINE data structures, the dwg_decode_SPLINE_private function attempts to allocate memory without proper bounds checking or size validation. This behavior creates an exploitable condition where an attacker can manipulate the memory allocation parameters through carefully constructed input data. The vulnerability falls under the CWE-122 category of "Heap-based Buffer Overflow" and represents a classic example of insufficient resource management in parsing routines. The flaw essentially allows an attacker to cause the application to attempt allocating excessive memory blocks, potentially leading to denial of service conditions or more severe consequences depending on the execution environment.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it represents a potential vector for remote code execution in systems that process untrusted DWG files. Applications utilizing GNU LibreDWG for DWG file processing, including CAD software, document viewers, and automated processing systems, could be affected by this vulnerability. The risk is particularly elevated in environments where users can upload or receive DWG files from untrusted sources, such as web applications, collaborative platforms, or document management systems. Attackers could leverage this vulnerability to cause system crashes, resource exhaustion, or potentially execute arbitrary code if the memory allocation failure leads to subsequent exploitation opportunities. This vulnerability aligns with ATT&CK technique T1203 "Exploitation for Client Execution" and represents a common class of vulnerabilities in parsing libraries that handle complex binary formats.
Mitigation strategies for CVE-2019-20009 primarily focus on immediate version upgrades to GNU LibreDWG 0.93 or later, which contain the necessary patches to address the memory allocation issue. Organizations should implement comprehensive input validation measures for all DWG file processing workflows, including size limits and format verification before parsing. Network segmentation and access controls should be enforced to limit exposure of systems that process untrusted DWG files. Additionally, implementing runtime monitoring and anomaly detection systems can help identify potential exploitation attempts by monitoring for unusual memory allocation patterns or process behavior. Security teams should also consider deploying sandboxing mechanisms when processing DWG files to contain potential exploitation attempts within isolated environments. The vulnerability serves as a reminder of the importance of robust input validation and memory management in parsing libraries, particularly those handling complex binary formats commonly used in engineering and design applications.