CVE-2008-4863 in Blender
Summary
by MITRE
Untrusted search path vulnerability in BPY_interface in Blender 2.46 allows local users to execute arbitrary code via a Trojan horse Python file in the current working directory, related to an erroneous setting of sys.path by the PySys_SetArgv function.
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Analysis
by VulDB Data Team • 08/02/2021
The vulnerability described in CVE-2008-4863 represents a classic untrusted search path issue that has significant implications for software security and code execution. This flaw exists within the BPY_interface component of Blender version 2.46, which serves as the Python interface for the popular 3D creation software. The vulnerability arises from how the application handles Python module loading and path resolution, specifically through the PySys_SetArgv function which incorrectly configures the Python system path. This misconfiguration creates a dangerous condition where malicious actors can exploit the application's trust in the current working directory to execute arbitrary code. The vulnerability is particularly concerning because it operates at the core of Blender's scripting infrastructure, which is essential for extending the software's functionality through Python plugins and scripts.
The technical implementation of this vulnerability stems from the improper handling of sys.path within the Python interpreter context of Blender. When the PySys_SetArgv function is invoked during application startup, it fails to properly sanitize or validate the Python path settings, allowing the current working directory to be included in the module search path without adequate security checks. This creates an environment where a local attacker can place a malicious Python file named identically to a legitimate module that Blender typically loads, effectively hijacking the module loading process. The flaw specifically affects the BPY_interface component, which is responsible for bridging Blender's C++ core with Python scripting capabilities, making it a critical attack vector for privilege escalation and code execution.
The operational impact of this vulnerability extends beyond simple code execution to encompass potential system compromise and data integrity violations. Local users can exploit this weakness to run malicious Python code with the privileges of the Blender process, which could potentially lead to unauthorized access to system resources, file manipulation, or even privilege escalation if the application runs with elevated permissions. The attack vector is particularly insidious because it requires no network connectivity and operates entirely within the local environment, making it difficult to detect through traditional network monitoring. This vulnerability aligns with CWE-427 Uncontrolled Search Path Element, which specifically addresses the issue of programs searching paths that include untrusted directories, and demonstrates how improper path handling can lead to arbitrary code execution. The flaw also intersects with ATT&CK technique T1059.006 for Python, as it leverages Python scripting capabilities to achieve malicious objectives.
Mitigation strategies for CVE-2008-4863 should focus on both immediate patching and defensive programming practices. The most effective solution involves updating to a patched version of Blender that properly handles sys.path configuration and removes the current working directory from the module search path when loading trusted Python modules. Organizations should implement strict file access controls and monitoring for suspicious Python file placements in directories where Blender applications operate. Additionally, security-conscious system administrators should consider implementing application whitelisting policies that restrict which Python files can be executed within the context of the Blender application. The vulnerability highlights the importance of secure coding practices around path resolution and module loading, particularly in applications that integrate scripting languages. System hardening measures should include regular security audits of Python environments and ensuring that applications properly sanitize all input paths to prevent malicious code injection through compromised module loading sequences.