CVE-2018-20775 in Frog
Summary
by MITRE
admin/?/plugin/file_manager in Frog CMS 0.9.5 allows PHP code execution by creating a new .php file containing PHP code, and then visiting this file under the public/ URI.
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Analysis
by VulDB Data Team • 07/09/2023
This vulnerability exists in Frog CMS version 0.9.5 within the administrative plugin file manager component where unauthorized users can execute arbitrary PHP code through a path traversal and file creation attack. The flaw occurs in the admin/?/plugin/file_manager endpoint which fails to properly validate file extensions and directory permissions, allowing attackers to upload malicious php files directly to the web root directory. The vulnerability is classified as a directory traversal issue that enables privilege escalation and remote code execution through a simple file upload mechanism. This represents a critical security flaw that aligns with CWE-22 Path Traversal and CWE-94 Code Injection categories, where improper input validation leads to unauthorized code execution. The attack vector is particularly dangerous because it allows an attacker to create php files in the public/ directory and subsequently access them through the web server, bypassing normal access controls. This vulnerability directly impacts the integrity and confidentiality of the web application by enabling persistent code execution capabilities that can be used to establish backdoors, exfiltrate data, or perform further attacks against the underlying infrastructure. The exploitation process involves creating a php file through the administrative interface and then accessing it via the public URI, which demonstrates a fundamental failure in access control and input sanitization.
The operational impact of this vulnerability is severe as it provides attackers with persistent remote code execution capabilities that can be leveraged for complete system compromise. Attackers can upload malicious scripts that remain persistent across system restarts and can be used to maintain long-term access to the compromised system. This vulnerability enables adversaries to execute commands with the privileges of the web server process, potentially leading to privilege escalation and lateral movement within the network. The attack follows the MITRE ATT&CK framework pattern for command and control through web shell deployment and persistence mechanisms, where the uploaded php files serve as execution points for malicious payloads. The vulnerability affects the availability, integrity, and confidentiality of the system as it allows for unauthorized data access, modification, and deletion. Organizations using Frog CMS 0.9.5 are particularly at risk because the vulnerability requires minimal privileges to exploit and can be automated through simple web-based attacks. The lack of proper file extension validation and directory access controls creates an attack surface that can be exploited by both authenticated and unauthenticated users depending on the system configuration.
Mitigation strategies for this vulnerability should focus on immediate patching of the Frog CMS application to version 0.9.6 or later where the file upload functionality has been properly secured. Administrators should implement strict file extension validation and ensure that the web server cannot execute php files from upload directories. The recommended approach includes configuring the web server to deny execution of php files in upload directories, implementing proper access controls through .htaccess files, and disabling the file manager plugin for non-administrative users. Additionally, organizations should implement network segmentation and monitoring to detect unauthorized file uploads and execution attempts. Security controls should include regular vulnerability assessments, input validation enforcement, and proper privilege separation between administrative and public directories. The implementation of web application firewalls and intrusion detection systems can help detect and prevent exploitation attempts. Organizations should also establish proper backup and recovery procedures to quickly restore systems in case of successful exploitation. This vulnerability highlights the critical importance of secure file handling practices and proper input validation in web applications, emphasizing the need for comprehensive security testing and regular security updates to prevent similar issues in the future.