CVE-2021-43336 in Drawings SDK
Summary
by MITRE • 11/15/2021
An Out-of-Bounds Write vulnerability exists when reading a DXF file using Open Design Alliance Drawings SDK before 2022.11. The specific issue exists within the parsing of DXF files. Crafted data in a DXF file (an invalid number of properties) can trigger a write operation past the end of an allocated buffer. An attacker can leverage this vulnerability to execute code in the context of the current process.
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Analysis
by VulDB Data Team • 11/16/2021
The vulnerability CVE-2021-43336 represents a critical out-of-bounds write flaw within the Open Design Alliance Drawings SDK, specifically affecting versions prior to 2022.11. This issue manifests during the parsing of DXF (Drawing Exchange Format) files, which are widely used in computer-aided design applications for exchanging design data between different software platforms. The vulnerability stems from inadequate input validation during the DXF file processing pipeline, where the SDK fails to properly validate the number of properties contained within certain data structures. When a maliciously crafted DXF file contains an invalid number of properties, the parsing routine attempts to write data beyond the boundaries of pre-allocated memory buffers, creating a condition that can be exploited by attackers.
The technical implementation of this vulnerability aligns with CWE-787, which describes out-of-bounds write conditions where a program writes data past the end of a buffer. The flaw occurs specifically within the DXF parsing logic where the SDK assumes a certain number of properties will be present in particular data sections without proper bounds checking. This allows an attacker to craft a DXF file with malformed property counts that cause the parser to write beyond allocated memory regions. The vulnerability is particularly dangerous because it can be triggered simply by opening a malicious DXF file, requiring no additional user interaction beyond the normal file opening process. The out-of-bounds write creates memory corruption that can be leveraged to overwrite adjacent memory locations, potentially leading to arbitrary code execution within the context of the running process.
From an operational perspective, this vulnerability presents a significant risk to organizations that rely on Open Design Alliance Drawings SDK for handling design files, particularly in environments where untrusted DXF files might be encountered. The attack surface extends to any application that utilizes this SDK for DXF file processing, including CAD applications, design review systems, and document management platforms. The exploitation of this vulnerability could allow remote attackers to execute malicious code with the privileges of the affected application, potentially leading to complete system compromise. The vulnerability's impact is amplified by the widespread use of DXF files in professional design environments where file sharing occurs frequently, increasing the likelihood of encountering maliciously crafted files. This flaw also maps to ATT&CK technique T1203, which involves the exploitation of software vulnerabilities for code execution, and T1059, covering command and scripting interpreter usage.
Mitigation strategies for CVE-2021-43336 focus primarily on upgrading to Open Design Alliance Drawings SDK version 2022.11 or later, which includes proper bounds checking and input validation mechanisms. Organizations should implement strict file validation procedures for DXF files, particularly those received from external sources, including content scanning and sandboxed processing environments. Network segmentation and access controls should be enforced to limit the potential impact of exploitation, while regular security assessments should be conducted to identify other potential vulnerabilities in the software supply chain. Additionally, implementing application whitelisting policies and monitoring for unusual file processing activities can help detect potential exploitation attempts. The vulnerability serves as a reminder of the critical importance of proper input validation and bounds checking in file parsing libraries, particularly in applications handling potentially untrusted data formats.