CVE-2021-4080 in crater
Summary
by MITRE • 01/12/2022
crater is vulnerable to Unrestricted Upload of File with Dangerous Type
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Analysis
by VulDB Data Team • 01/15/2022
The vulnerability identified as CVE-2021-4080 affects the crater application and represents a critical security flaw categorized under unrestricted file upload with dangerous type. This vulnerability falls under the broader category of insecure file handling within web applications and specifically aligns with CWE-434 which addresses unrestricted upload of file with dangerous type. The flaw enables attackers to upload malicious files to the target system without proper validation or sanitization, creating potential pathways for arbitrary code execution and system compromise.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the file upload functionality of the crater application. When users attempt to upload files through the application interface, the system fails to properly verify the file type, content, or extensions against a whitelist of acceptable formats. This weakness allows adversaries to bypass security controls and upload files with dangerous extensions such as .php, .asp, .jsp, or other executable formats that can be interpreted by the web server. The vulnerability exists at the application layer where file upload operations are processed, typically without proper MIME type checking or content analysis.
The operational impact of CVE-2021-4080 is severe and multifaceted, potentially enabling attackers to achieve remote code execution, data breaches, and complete system compromise. An attacker who successfully exploits this vulnerability can upload a malicious web shell or script that executes arbitrary commands on the target server with the privileges of the web application. This could lead to unauthorized access to sensitive data, modification of application files, privilege escalation, and persistence within the compromised environment. The vulnerability also poses risks for cross-site scripting attacks and can be leveraged as a stepping stone for further network exploitation. According to ATT&CK framework, this vulnerability maps to T1190 - Exploit Public-Facing Application and T1059 - Command and Scripting Interpreter, demonstrating the attack vectors available to threat actors.
Mitigation strategies for CVE-2021-4080 should implement multiple layers of defense to prevent unauthorized file uploads. Organizations must establish strict file type validation using whitelisting approaches rather than blacklisting, ensuring only known safe file extensions are accepted. Implementing proper MIME type checking, content analysis, and file header validation can significantly reduce the risk of malicious file uploads. Additionally, uploaded files should be stored in non-executable directories, and proper access controls should be enforced to prevent direct execution of uploaded content. The application should also implement proper file naming conventions and sanitize all uploaded files to remove potentially malicious content. Regular security testing, including penetration testing and code reviews, should be conducted to identify and remediate similar vulnerabilities in the application's file handling mechanisms.