CVE-2020-21832 in LibreDWG
Summary
by MITRE • 05/18/2021
A heap based buffer overflow vulnerability exists in GNU LibreDWG 0.10 via read_2004_compressed_section ../../src/decode.c:2417.
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Analysis
by VulDB Data Team • 05/22/2021
The heap-based buffer overflow vulnerability identified as CVE-2020-21832 resides within GNU LibreDWG version 0.10, specifically within the read_2004_compressed_section function located in the ../../src/decode.c file at line 2417. This vulnerability represents a critical security flaw that can be exploited to execute arbitrary code or cause application crashes when processing specially crafted DWG files. The vulnerability stems from insufficient input validation and bounds checking during the decompression of 2004 format DWG files, which are commonly used in computer-aided design applications. The affected software library serves as a crucial component for reading and writing DWG files, making it a prime target for attackers seeking to compromise systems that rely on this library for file processing operations.
The technical implementation of this vulnerability involves a heap-based buffer overflow condition where the application fails to properly validate the size of data being read from compressed DWG sections. When the read_2004_compressed_section function processes malformed input data, it attempts to write data beyond the allocated heap buffer boundaries, creating a condition where adjacent memory locations can be overwritten. This flaw falls under CWE-121 Heap-based Buffer Overflow, which is classified as a serious weakness in software security that allows attackers to manipulate memory contents and potentially execute malicious code. The vulnerability is particularly dangerous because it occurs during the decompression phase of DWG file processing, meaning that simply opening or parsing a malicious file can trigger the exploit.
The operational impact of this vulnerability extends across various environments where GNU LibreDWG is integrated into applications or systems handling DWG files. Attackers can leverage this flaw to execute remote code execution against systems processing untrusted DWG content, potentially leading to complete system compromise. The vulnerability affects not only individual user systems but also enterprise environments where CAD software and document processing pipelines are prevalent. Systems running applications that utilize LibreDWG for DWG file handling, including CAD applications, document management systems, and automated processing workflows, are at risk. The exploitation of this vulnerability can result in denial of service conditions, data corruption, or unauthorized access to sensitive information contained within CAD files.
Mitigation strategies for CVE-2020-21832 should prioritize immediate software updates and patches from the GNU LibreDWG maintainers, as this vulnerability has been addressed in subsequent releases of the software. Organizations should implement strict input validation measures and sanitize all DWG file inputs before processing, particularly when handling files from untrusted sources. Network segmentation and access controls should be enforced to limit exposure of systems that process DWG files, while regular security audits should be conducted to identify potential attack vectors. The vulnerability demonstrates the importance of proper bounds checking and memory management practices in security-critical applications, aligning with ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1203 for Exploitation for Client Execution. Additionally, implementing application whitelisting and using sandboxing techniques can provide additional layers of protection against exploitation attempts targeting this heap-based buffer overflow vulnerability.