CVE-2023-5812 in flusity
Summary
by MITRE • 10/27/2023
A vulnerability has been found in flusity CMS and classified as critical. Affected by this vulnerability is the function handleFileUpload of the file core/tools/upload.php. The manipulation of the argument uploaded_file leads to unrestricted upload. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. This product does not use versioning. This is why information about affected and unaffected releases are unavailable. The associated identifier of this vulnerability is VDB-243643.
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Analysis
by VulDB Data Team • 11/18/2023
The vulnerability identified as CVE-2023-5812 represents a critical security flaw in the flusity CMS platform that exposes organizations to significant risks through unrestricted file upload capabilities. This vulnerability resides within the core/tools/upload.php file and specifically targets the handleFileUpload function, making it a prime target for attackers seeking to compromise web applications. The flaw allows malicious actors to upload arbitrary files to the server without proper validation or sanitization, creating a pathway for code execution and potential system compromise. The vulnerability's remote exploitation capability means that attackers do not require physical access to the system and can target the CMS from anywhere on the internet, significantly expanding the attack surface and potential impact.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the file upload handling mechanism. When the uploaded_file argument is processed through the handleFileUpload function, no proper restrictions are enforced on file types, content, or execution permissions. This lack of validation creates a direct pathway for attackers to upload malicious files such as web shells, malware, or other executable code that can be executed within the context of the web server. The vulnerability directly maps to CWE-434, which specifically addresses the insecure upload of code or files, and aligns with ATT&CK technique T1190 for exploiting vulnerabilities in web applications. The absence of versioning in the affected product complicates remediation efforts as organizations cannot easily determine which versions are vulnerable or patched, creating additional operational challenges for security teams.
The operational impact of this vulnerability extends beyond simple unauthorized file uploads and can lead to complete system compromise. Attackers can leverage this flaw to establish persistent backdoors, exfiltrate sensitive data, perform lateral movement within networks, or use the compromised server as a launching point for further attacks. The unrestricted nature of the upload capability means that attackers can deploy various types of malicious payloads including php shells, javascript exploits, or binary malware that can operate with the privileges of the web server. Organizations running flusity CMS without proper mitigations face risks of data breaches, service disruption, and potential regulatory compliance violations. The public disclosure of the exploit further amplifies the risk as threat actors can immediately implement attacks against vulnerable systems without requiring advanced technical skills or extensive reconnaissance.
Effective mitigation strategies for CVE-2023-5812 must address both immediate remediation and long-term security hardening measures. Organizations should implement strict file type validation and content checking mechanisms that prevent execution of potentially malicious files, including rejecting common web shell extensions and performing MIME type verification. The implementation of proper file upload restrictions including size limits, directory permissions, and secure file storage practices can significantly reduce the attack surface. Security teams should consider deploying web application firewalls with rules specifically designed to detect and block file upload attempts that bypass normal validation. Additionally, organizations should conduct comprehensive security assessments of their web applications, implement proper access controls, and establish monitoring procedures to detect unauthorized file upload activities. The vulnerability's classification as critical necessitates immediate action, and organizations should prioritize patching or implementing compensating controls to protect against exploitation. Regular security audits and penetration testing should be conducted to identify similar vulnerabilities in other components of the web application stack.