CVE-2012-4389 in ownCloud
Summary
by MITRE
Incomplete blacklist vulnerability in lib/migrate.php in ownCloud before 4.0.7 allows remote attackers to execute arbitrary code by uploading a crafted .htaccess file in an import.zip file and accessing an uploaded PHP file.
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Analysis
by VulDB Data Team • 03/31/2025
The vulnerability CVE-2012-4389 represents a critical security flaw in the ownCloud file synchronization and sharing platform that affected versions prior to 4.0.7. This issue resides within the lib/migrate.php component and demonstrates a classic incomplete blacklist security pattern that has been classified under CWE-20. The vulnerability specifically targets the application's handling of imported files through zip archives, creating a path for remote code execution that could be exploited by malicious actors without requiring authentication or elevated privileges. The flaw manifests when the system processes import.zip files containing crafted .htaccess files that bypass the intended security restrictions, allowing attackers to upload and subsequently execute arbitrary PHP code on the target server.
The technical implementation of this vulnerability exploits the incomplete blacklist mechanism used by ownCloud to filter file types during import operations. When users upload zip archives containing malicious .htaccess files, the application fails to properly validate or sanitize these files before processing them within the web root directory. The .htaccess file serves as a critical attack vector because it can modify server behavior and configuration, particularly when placed in directories accessible via web requests. The vulnerability becomes particularly dangerous when combined with the ability to upload PHP files that can be executed directly through the web server, as the malicious .htaccess file can configure the server to treat these PHP files as executable content. This creates a scenario where attackers can upload a .htaccess file that modifies the server's behavior to execute PHP code from uploaded files, effectively bypassing the intended security controls and allowing for arbitrary code execution.
The operational impact of CVE-2012-4389 extends far beyond simple data theft or modification, as it provides attackers with complete server compromise capabilities. Once exploited, the vulnerability allows attackers to execute commands with the privileges of the web server process, potentially leading to full system compromise, data exfiltration, or the installation of backdoors. The attack requires minimal privileges from the attacker's perspective since it operates entirely through web-based interfaces without needing direct system access or authentication. This makes the vulnerability particularly dangerous in environments where ownCloud is used for enterprise file sharing, as it could enable attackers to gain access to sensitive corporate data, user files, and potentially propagate to other systems within the network. The vulnerability also demonstrates poor input validation practices that align with ATT&CK technique T1059.007 for Command and Scripting Interpreter, as the system fails to properly validate file content and execution paths.
The mitigation strategies for this vulnerability primarily focus on immediate patching and implementation of proper file validation mechanisms. Organizations should immediately upgrade to ownCloud version 4.0.7 or later, which contains the necessary fixes to address the incomplete blacklist issue. The patch addresses the core problem by implementing proper file type validation and ensuring that .htaccess files are properly sanitized or rejected during import operations. Additional security measures include implementing stricter file content validation, using allowlists instead of blacklists for file type restrictions, and configuring web server security settings to prevent execution of uploaded files. Organizations should also consider implementing web application firewalls to detect and block suspicious file upload patterns, and establish monitoring procedures to detect unauthorized file uploads or modifications to server configuration files. The vulnerability serves as a reminder of the critical importance of proper input validation and the dangers of relying solely on blacklist-based security controls, as highlighted in CWE-20's emphasis on incomplete blacklist validation patterns that should be replaced with more robust allowlist approaches.