CVE-2009-0318 in Gnumeric
Summary
by MITRE
Untrusted search path vulnerability in the GObject Python interpreter wrapper in Gnumeric allows local users to execute arbitrary code via a Trojan horse Python file in the current working directory, related to a vulnerability in the PySys_SetArgv function (CVE-2008-5983).
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Analysis
by VulDB Data Team • 08/26/2019
The vulnerability identified as CVE-2009-0318 represents a critical untrusted search path weakness within the GObject Python interpreter wrapper component of Gnumeric spreadsheet software. This flaw specifically manifests in the PySys_SetArgv function which is responsible for setting up the Python interpreter's command line arguments and environment. The vulnerability arises from the interpreter's failure to properly validate or sanitize the search path used when loading Python modules, creating an exploitable condition where malicious actors can manipulate the execution flow through carefully crafted file placement.
The technical implementation of this vulnerability stems from the improper handling of Python module loading sequences within the Gnumeric environment. When the GObject Python wrapper processes Python scripts, it relies on the standard Python interpreter's module resolution mechanism which searches through a predefined list of directories in a specific order. The vulnerability occurs because the current working directory is placed at a privileged position in this search sequence, allowing an attacker to place a malicious Python file with the same name as a legitimate module that Gnumeric attempts to load. This creates a path traversal scenario where the interpreter loads the attacker-controlled file instead of the intended system module, effectively enabling arbitrary code execution.
The operational impact of CVE-2009-0318 extends beyond simple privilege escalation to encompass full system compromise capabilities for local attackers. Since the vulnerability requires only local access to the target system, it can be exploited by any user with access to the affected machine, making it particularly dangerous in multi-user environments or when users execute Gnumeric with elevated privileges. The attack vector is particularly insidious because it leverages the legitimate module loading mechanisms of Python, making detection more challenging for security monitoring systems that might not flag the execution of malicious code within expected application workflows. This vulnerability directly maps to CWE-427 Uncontrolled Search Path Element and CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component, both of which are recognized as high-risk categories in the Common Weakness Enumeration catalog.
The exploitation of this vulnerability aligns with several tactics described in the MITRE ATT&CK framework, particularly those related to privilege escalation and execution through legitimate system processes. Attackers can leverage this weakness to establish persistent access or escalate privileges within the target environment, especially when Gnumeric is executed with elevated permissions or when users frequently interact with spreadsheet files from untrusted sources. The vulnerability also demonstrates characteristics consistent with ATT&CK technique T1059 Command and Scripting Interpreter, where the attacker uses the interpreter's legitimate functionality to execute malicious code. Organizations using Gnumeric should consider this vulnerability in their risk assessment frameworks and implement appropriate mitigations to prevent exploitation.
Mitigation strategies for CVE-2009-0318 should focus on both immediate defensive measures and long-term architectural improvements. The most effective immediate solution involves updating to patched versions of Gnumeric that address the underlying PySys_SetArgv vulnerability, which was resolved in subsequent releases. System administrators should also implement strict directory permissions and monitoring to prevent unauthorized file creation in directories where Gnumeric executes. Additionally, organizations should consider implementing application whitelisting policies that restrict which Python files can be executed within the Gnumeric environment, and deploy runtime application control mechanisms that monitor for suspicious module loading patterns. The vulnerability serves as a reminder of the importance of secure coding practices in interpreter environments and the need for comprehensive input validation and search path sanitization in applications that interface with scripting languages.