CVE-2020-23138 in Microweber
Summary
by MITRE • 11/10/2020
An unrestricted file upload vulnerability was discovered in the Microweber 1.1.18 admin account page. An attacker can upload PHP code or any extension (eg- .exe) to the web server by providing image data and the image/jpeg content type with a .php extension.
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Analysis
by VulDB Data Team • 12/04/2020
The vulnerability identified as CVE-2020-23138 represents a critical unrestricted file upload flaw within the Microweber content management system version 1.1.18 administrative interface. This vulnerability stems from insufficient input validation and sanitization mechanisms that fail to properly verify file types and content before allowing file uploads to the web server. The flaw specifically affects the admin account page where users with administrative privileges can upload files, creating a significant attack surface that adversaries can exploit to gain unauthorized access to the underlying server infrastructure.
The technical implementation of this vulnerability occurs when the application accepts file uploads without proper validation of file extensions or content type checks. Attackers can manipulate the upload process by crafting malicious requests that present PHP code with a .php extension while spoofing the image/jpeg content type header. This technique bypasses typical security measures that rely on content type verification and file extension filtering, allowing the upload of executable code that can be executed on the web server. The vulnerability is classified under CWE-434 Unrestricted Upload of File with Dangerous Type, which specifically addresses the risk of uploading files that can be executed by the web server.
The operational impact of this vulnerability is severe and multifaceted, potentially enabling full system compromise through remote code execution. Once an attacker successfully uploads malicious code, they can execute arbitrary commands on the web server, potentially leading to complete system takeover, data exfiltration, or deployment of additional malware. The vulnerability also creates persistent backdoor access points that can remain undetected for extended periods, making it particularly dangerous for long-term compromise. According to ATT&CK framework, this vulnerability maps to T1190 Exploit Public-Facing Application and T1059 Command and Scripting Interpreter, as it allows adversaries to execute code through web application interfaces.
Mitigation strategies for CVE-2020-23138 should focus on implementing robust file validation mechanisms that enforce strict content type checking and file extension filtering. Organizations should implement multiple layers of defense including mandatory file type validation, content type verification, and file content analysis to prevent malicious uploads. The recommended approach includes implementing whitelisting of allowed file extensions, mandatory file content verification, and storing uploaded files outside the web root directory to prevent direct execution. Additionally, implementing proper access controls and regular security audits of file upload functionality can help detect and prevent exploitation attempts. The vulnerability highlights the importance of following secure coding practices as outlined in OWASP Top Ten and NIST cybersecurity guidelines for preventing file upload vulnerabilities in web applications.