CVE-2019-9775 in LibreDWG
Summary
by MITRE
An issue was discovered in GNU LibreDWG 0.7 and 0.7.1645. There is an out-of-bounds read in the function dwg_dxf_BLOCK_CONTROL at dwg.spec.
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Analysis
by VulDB Data Team • 08/01/2023
The vulnerability identified as CVE-2019-9775 represents a critical out-of-bounds read condition within GNU LibreDWG version 0.7 and 0.7.1645, specifically within the dwg_dxf_BLOCK_CONTROL function located in the dwg.spec file. This issue arises from inadequate input validation and boundary checking mechanisms that fail to properly verify the size and content of data structures during the processing of CAD drawing files. The flaw manifests when the software attempts to read memory locations beyond the allocated buffer boundaries, potentially leading to unpredictable behavior and system instability.
The technical implementation of this vulnerability stems from the improper handling of block control data structures within the DXF (Drawing Exchange Format) parsing functionality. When processing maliciously crafted CAD files, the dwg_dxf_BLOCK_CONTROL function does not perform adequate bounds checking before accessing array elements or memory regions. This allows an attacker to manipulate the input data in such a way that the function reads beyond its intended memory allocation, creating opportunities for information disclosure, denial of service, or potentially remote code execution depending on the system configuration and memory layout. The vulnerability falls under 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 memory corruption issues.
The operational impact of CVE-2019-9775 extends beyond simple system instability, as it creates potential entry points for attackers to exploit the memory corruption vulnerability. Systems utilizing GNU LibreDWG for CAD file processing, including engineering firms, architectural offices, and manufacturing environments, face significant risks when processing untrusted drawing files. An attacker could craft a malicious DXF file that triggers the out-of-bounds read during normal file parsing operations, potentially leading to system crashes, data leakage, or more severe consequences depending on the execution environment. The vulnerability is particularly concerning in automated processing environments where files are processed without human intervention, as it could enable remote exploitation without user interaction.
Mitigation strategies for this vulnerability should focus on immediate patching of affected GNU LibreDWG installations to the latest stable versions that contain proper bounds checking implementations. System administrators should implement strict file validation procedures, including content scanning and sandboxing of CAD file processing operations to prevent exploitation. The ATT&CK framework categorizes this type of vulnerability under T1059 Command and Scripting Interpreter and T1203 Exploitation for Client Execution, as it represents a classic memory corruption exploit that can be leveraged for privilege escalation or system compromise. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of exploitation, while monitoring for unusual file processing patterns that might indicate attempted exploitation of this vulnerability.