CVE-2012-5534 in WeeChat
Summary
by MITRE
The hook_process function in the plugin API for WeeChat 0.3.0 through 0.3.9.1 allows remote attackers to execute arbitrary commands via shell metacharacters in a command from a plugin, related to "shell expansion."
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Analysis
by VulDB Data Team • 12/20/2021
The vulnerability identified as CVE-2012-5534 represents a critical command injection flaw within the WeeChat IRC client's plugin application programming interface. This vulnerability exists in versions 0.3.0 through 0.3.9.1 of the software, where the hook_process function fails to properly sanitize user input before executing shell commands. The flaw specifically manifests when plugins attempt to process commands that contain shell metacharacters, creating an environment where malicious actors can inject arbitrary shell commands through crafted plugin inputs.
The technical implementation of this vulnerability stems from improper input validation within the plugin API's command processing mechanism. When a plugin invokes the hook_process function with user-supplied data, the system performs shell expansion without adequate sanitization of special characters such as semicolons, ampersands, backticks, or other metacharacters that could alter command execution flow. This design flaw falls under the CWE-78 category of "Improper Neutralization of Special Elements used in an OS Command" and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: Unix Shell." The vulnerability creates a direct path for remote code execution when malicious input containing shell metacharacters is processed through the plugin interface.
The operational impact of this vulnerability is severe and far-reaching within the WeeChat ecosystem. Remote attackers can exploit this weakness to execute arbitrary commands on systems running vulnerable versions of WeeChat, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it operates within the plugin API context, meaning that malicious actors could leverage legitimate plugin functionality to gain unauthorized access. This creates a sophisticated attack vector that bypasses traditional security controls since the commands are executed through what appears to be legitimate plugin processes. The vulnerability affects not only the local system but also any network services or applications that rely on WeeChat's plugin infrastructure for command processing.
Mitigation strategies for CVE-2012-5534 should prioritize immediate version upgrades to WeeChat 0.3.9.2 or later, which contain the necessary patches to address the command injection vulnerability. Organizations should implement strict input validation measures within their plugin development practices, ensuring that all user-supplied data is properly sanitized before processing. The implementation of principle of least privilege for plugin execution contexts can significantly reduce the impact of potential exploitation. Additionally, network segmentation and monitoring of plugin API communications can help detect anomalous command execution patterns. Security professionals should also consider implementing web application firewalls or similar protective measures that can identify and block malicious shell metacharacter sequences. The vulnerability demonstrates the critical importance of secure coding practices in plugin architectures and highlights the need for comprehensive input validation across all system interfaces that handle external data processing.