CVE-2021-45845 in FreeCAD
Summary
by MITRE • 01/25/2022
The Path Sanity Check script of FreeCAD 0.19 is vulnerable to OS command injection, allowing an attacker to execute arbitrary commands via a crafted FCStd document.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 01/28/2022
The vulnerability identified as CVE-2021-45845 resides within the Path Sanity Check script component of FreeCAD version 0.19, representing a critical security flaw that enables unauthorized command execution through manipulated file inputs. This issue specifically targets the document processing mechanism where FreeCAD handles FCStd files, which are the native file format used by the software for storing 3d model data and associated parameters. The flaw stems from inadequate input validation and sanitization within the script responsible for verifying path integrity during document loading operations.
Technical exploitation of this vulnerability occurs when a malicious actor crafts a specially designed FCStd document that contains embedded commands intended to be executed by the underlying operating system. The Path Sanity Check script fails to properly sanitize user-supplied path data, allowing attacker-controlled input to be interpreted and executed as shell commands. This represents a classic operating system command injection vulnerability that can be classified under CWE-78, which specifically addresses improper neutralization of special elements used in OS commands. The vulnerability exists because the script directly incorporates user-provided path information into system calls without adequate filtering or escaping mechanisms.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it allows remote code execution on systems running vulnerable versions of FreeCAD. An attacker could potentially execute arbitrary commands with the privileges of the user running FreeCAD, which may include administrative rights depending on the system configuration. This risk is particularly concerning given that FreeCAD is widely used in engineering and design environments where users frequently open documents from untrusted sources, including email attachments, shared network drives, or downloaded files from websites. The attack surface is broad as any user who opens a malicious FCStd file could become compromised, making this vulnerability particularly dangerous in collaborative or shared computing environments.
Mitigation strategies for CVE-2021-45845 should prioritize immediate patching of FreeCAD to version 0.20 or later where the vulnerability has been addressed through proper input validation and sanitization of path data. System administrators should implement restrictive file access controls and user permissions to limit the potential impact of successful exploitation attempts. Network segmentation and application whitelisting can help prevent unauthorized file execution by limiting which systems can process FCStd documents. Additionally, security monitoring should be enhanced to detect suspicious file access patterns and command execution attempts. From an ATT&CK framework perspective, this vulnerability maps to techniques involving command injection and privilege escalation, with potential lateral movement capabilities if the compromised system has elevated privileges. Organizations should also consider implementing sandboxing mechanisms for document processing and regular security awareness training for users handling potentially malicious files to reduce the likelihood of successful exploitation attempts.