CVE-2015-2780 in Berta
Summary
by MITRE
Unrestricted file upload vulnerability in Berta CMS allows remote attackers to execute arbitrary code by uploading a crafted image file with an executable extension, then accessing it via a direct request to the file in an unspecified directory.
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Analysis
by VulDB Data Team • 01/12/2025
The vulnerability identified as CVE-2015-2780 represents a critical unrestricted file upload flaw within Berta CMS, a content management system widely used for creating and managing websites. This vulnerability stems from insufficient input validation and sanitization mechanisms that fail to properly verify the file types being uploaded to the server. The flaw allows remote attackers to bypass security restrictions and upload malicious files that can execute arbitrary code on the target system.
The technical implementation of this vulnerability occurs when the CMS does not adequately validate file extensions or content types during the upload process. Attackers can craft image files with executable extensions such as .php, .asp, or .jsp that appear to be legitimate media files but contain malicious payloads. The system accepts these files without proper verification, storing them in directories accessible via web requests. When an attacker accesses the uploaded file directly through a web browser or HTTP request, the server executes the embedded code, providing remote code execution capabilities.
This vulnerability directly maps to CWE-434, which describes unrestricted file upload or file type validation issues in software systems. The operational impact of this flaw is severe as it allows attackers to gain full control over the affected server, potentially leading to data breaches, system compromise, and further lateral movement within network environments. The unspecified directory access pattern suggests that the uploaded files may be stored in predictable locations or that the system's directory structure does not properly isolate uploaded content from executable scripts.
The attack vector leverages the principle of least privilege violation, where the CMS fails to enforce proper access controls on uploaded files. This vulnerability enables attackers to perform various malicious activities including but not limited to data exfiltration, establishing persistent backdoors, and using the compromised server as a launching point for attacks against other systems. The remote nature of the exploit means that attackers do not require physical access or local system credentials to exploit this vulnerability.
Mitigation strategies for CVE-2015-2780 should include implementing robust file type validation mechanisms that check both file extensions and MIME types against comprehensive whitelists of allowed formats. Organizations should employ proper file upload sanitization techniques such as renaming uploaded files to random strings, storing them outside the web root directory, and implementing strict access controls on uploaded content. Additionally, the CMS should be updated to the latest version that includes proper input validation and sanitization patches. Security configurations should enforce proper file permissions and implement Content Security Policies to prevent execution of uploaded files. The vulnerability also highlights the importance of following secure coding practices and implementing defense-in-depth strategies to prevent similar issues in other web applications. Organizations should conduct regular security assessments and penetration testing to identify and remediate such vulnerabilities before they can be exploited by malicious actors.