CVE-2018-9037 in Monstra
Summary
by MITRE
Monstra CMS 3.0.4 allows remote code execution via an upload_file request for a .zip file, which is automatically extracted and may contain .php files.
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Analysis
by VulDB Data Team • 02/27/2023
The vulnerability identified as CVE-2018-9037 represents a critical remote code execution flaw within Monstra CMS version 3.0.4 that directly impacts the security posture of affected web applications. This vulnerability stems from insufficient input validation and improper file handling mechanisms within the content management system's file upload functionality. The specific weakness occurs when the system processes upload_file requests for zip archives, creating a pathway for malicious actors to execute arbitrary code on the target server. The vulnerability is classified under CWE-434 which specifically addresses "Upload of a File with a Dangerous Type" and aligns with ATT&CK technique T1190 "Exploit Public-Facing Application" as it enables remote exploitation through web application interfaces.
The technical exploitation of this vulnerability occurs through a carefully crafted zip file that contains malicious php scripts within its contents. When the CMS automatically extracts these zip archives without proper sanitization or validation of file types, the embedded php files become executable within the web server context. This automatic extraction process bypasses normal security controls that would typically prevent direct execution of php files in upload directories. The vulnerability demonstrates poor secure coding practices where the application assumes that zip files are benign and automatically processes their contents without verifying the integrity or content types of individual files within the archive. This flaw is particularly dangerous because it operates at the file system level and can potentially grant attackers full control over the web server.
The operational impact of this vulnerability extends beyond simple code execution to encompass complete system compromise and data exfiltration capabilities. An attacker who successfully exploits this vulnerability can upload malicious php files that persist on the server and can be executed at any time, providing a backdoor for continued access. The vulnerability also enables privilege escalation scenarios where attackers can manipulate the CMS to gain administrative access, potentially leading to full system compromise. The automatic extraction feature creates a persistent threat vector that remains active as long as the vulnerable CMS version is operational, making it particularly attractive to threat actors seeking long-term access to compromised systems. This vulnerability directly relates to ATT&CK technique T1059 "Command and Scripting Interpreter" as attackers can execute arbitrary commands through the uploaded php scripts.
Mitigation strategies for CVE-2018-9037 require immediate action including patching the CMS to a version that properly validates and sanitizes uploaded files, implementing strict file type validation that rejects zip archives containing php files, and configuring the web server to prevent execution of php files in upload directories. Organizations should also implement network segmentation and monitoring to detect suspicious file upload activities. The remediation process must include disabling automatic extraction of zip files within the CMS, implementing proper content validation for all uploaded files, and establishing secure file handling procedures that align with industry standards such as those recommended by the OWASP Top Ten. Additionally, regular security assessments and penetration testing should be conducted to identify similar vulnerabilities in other web applications and ensure that file upload mechanisms are properly secured against similar attack vectors.