CVE-2019-9185 in Bolt
Summary
by MITRE
Controller/Async/FilesystemManager.php in the filemanager in Bolt before 3.6.5 allows remote attackers to execute arbitrary PHP code by renaming a previously uploaded file to have a .php extension.
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Analysis
by VulDB Data Team • 07/29/2023
The vulnerability described in CVE-2019-9185 represents a critical security flaw in the Bolt content management system's file management functionality. This issue exists within the Controller/Async/FilesystemManager.php component which handles asynchronous file operations through the Bolt filemanager interface. The vulnerability stems from insufficient input validation and improper file extension handling during the file renaming process, creating a path for remote attackers to execute arbitrary PHP code on the affected server. The flaw specifically occurs when an attacker uploads a file with a non-PHP extension and subsequently renames it to include a .php extension through the administrative interface.
The technical implementation of this vulnerability falls under CWE-434, which specifically addresses "Unrestricted Upload of File with Dangerous Type." The vulnerability allows attackers to bypass normal file type restrictions by leveraging the file renaming functionality to transform previously uploaded files into executable PHP scripts. When the renamed file is subsequently accessed through the web server, the PHP interpreter executes the malicious code contained within the file. This represents a classic case of insecure file handling where the application fails to properly validate file extensions during modification operations, particularly when files are moved or renamed within the filesystem.
The operational impact of this vulnerability is severe as it provides remote code execution capabilities to any authenticated user with access to the filemanager interface. In a typical Bolt installation, this could allow attackers to gain full control over the web server, execute arbitrary commands, access sensitive data, modify content, or establish persistent backdoors. The vulnerability is particularly dangerous because it does not require special privileges beyond basic administrative access to the filemanager functionality, making it exploitable by users with relatively limited permissions. Attackers could potentially use this vulnerability to deploy web shells, exfiltrate database credentials, or compromise the entire hosting environment.
Mitigation strategies for this vulnerability should include immediate application updates to version 3.6.5 or later, which contains the necessary patches to address the file extension validation issue. Organizations should implement strict file type validation mechanisms that prevent any file from being renamed to have a PHP extension, regardless of its original type or the user performing the operation. Additionally, implementing proper file upload restrictions, such as disabling PHP execution in upload directories and implementing Content Security Policies, can significantly reduce the risk of exploitation. The solution should also include monitoring for unauthorized file modifications and implementing principle of least privilege access controls for filemanager functionality. This vulnerability demonstrates the importance of proper input validation and the principle that all user-supplied data should be treated as potentially malicious, aligning with ATT&CK technique T1059.007 for Command and Scripting Interpreter: PHP. Organizations should also consider implementing web application firewalls and regular security audits to detect and prevent similar vulnerabilities in other components of their web applications.