CVE-2014-2044 in ownCloud
Summary
by MITRE
Incomplete blacklist vulnerability in ajax/upload.php in ownCloud before 5.0, when running on Windows, allows remote authenticated users to bypass intended access restrictions, upload files with arbitrary names, and execute arbitrary code via an Alternate Data Stream (ADS) syntax in the filename parameter, as demonstrated using .htaccess::$DATA to upload a PHP program.
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Analysis
by VulDB Data Team • 03/31/2025
The vulnerability identified as CVE-2014-2044 represents a critical access control flaw in ownCloud versions prior to 5.0, specifically affecting installations running on Windows operating systems. This issue stems from an incomplete blacklist implementation in the ajax/upload.php file that fails to properly validate file names submitted by authenticated users. The vulnerability is particularly dangerous because it allows remote attackers to circumvent intended security restrictions through the exploitation of Windows Alternate Data Streams functionality. The technical implementation of this flaw demonstrates a fundamental misunderstanding of how file systems handle metadata and access controls, particularly in Windows environments where ADS provides a mechanism for storing additional data streams within files.
The exploitation technique leverages the Windows file system's Alternate Data Streams feature, which allows multiple data streams to be associated with a single file. Attackers can append specific syntax to file names to create files with hidden streams, such as using the .htaccess::$DATA pattern to upload PHP programs. This approach bypasses traditional file extension filtering mechanisms because the system processes the file name through an incomplete validation routine that does not account for Windows-specific file system behaviors. The vulnerability operates at the intersection of file system security and application-level access controls, creating a scenario where legitimate file upload functionality can be subverted for malicious purposes.
The operational impact of this vulnerability extends beyond simple unauthorized file uploads, as it enables arbitrary code execution capabilities within the web application context. When attackers successfully upload PHP files using the ADS technique, they can execute malicious code on the server with the privileges of the web application, potentially leading to full system compromise. The attack vector requires authentication, meaning that an attacker must first obtain valid credentials, but once achieved, the vulnerability provides a pathway for privilege escalation and persistent access. This weakness creates a significant risk for organizations relying on ownCloud for file sharing and collaboration, particularly in environments where Windows servers are deployed and where users may have elevated privileges.
Mitigation strategies for this vulnerability should address both the immediate technical flaw and broader security practices. The primary solution involves implementing proper input validation that accounts for Windows file system behaviors and rejects potentially dangerous file name patterns including ADS syntax. Security patches should enforce comprehensive whitelisting of acceptable file types rather than relying on incomplete blacklists, aligning with security best practices outlined in the OWASP Top Ten and CWE-170 for improper input handling. Organizations should also implement additional controls such as file content analysis, mandatory file type verification, and restricted file upload directories to minimize the impact of any remaining vulnerabilities. The ATT&CK framework categorizes this type of vulnerability under T1059 for execution through command and scripting interpreters, making it particularly relevant for defensive security teams to monitor and restrict file upload activities that could lead to code execution.
This vulnerability highlights the importance of considering platform-specific security features when implementing application-level controls, particularly in multi-platform environments where different operating systems may have unique file handling characteristics. The incomplete blacklist approach demonstrates a common security anti-pattern that should be avoided in favor of robust validation techniques that consider all possible attack vectors. Security professionals should ensure that their applications properly validate file names against known dangerous patterns and implement comprehensive testing that includes platform-specific edge cases to prevent similar vulnerabilities from being introduced in future development cycles.