CVE-2020-36141 in BloofoxCMS
Summary
by MITRE • 06/04/2021
BloofoxCMS 0.5.2.1 allows Unrestricted File Upload vulnerability via bypass MIME Type validation by inserting 'image/jpeg' within the 'Content-Type' header.
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Analysis
by VulDB Data Team • 06/10/2021
The vulnerability identified as CVE-2020-36141 affects BloofoxCMS version 0.5.2.1 and represents a critical unrestricted file upload flaw that enables remote attackers to execute arbitrary code on the affected system. This vulnerability stems from inadequate input validation mechanisms within the file upload functionality, specifically targeting the MIME type validation process. The flaw allows malicious actors to bypass security controls by manipulating the Content-Type header to include 'image/jpeg' even when uploading files that are not actually image files, thereby circumventing the intended security restrictions.
The technical implementation of this vulnerability involves the manipulation of HTTP headers during file upload operations, particularly the Content-Type field which is used to determine the file type and validate uploads. Attackers can craft malicious requests where the Content-Type header contains 'image/jpeg' while the actual file content may be a malicious script or executable file. This bypass technique exploits the CMS's reliance on header-based validation rather than comprehensive file content analysis, creating a path for attackers to upload potentially harmful files such as php shells, web shells, or other malicious executables that can be executed within the web server context.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with direct execution capabilities on the target system. Once successfully exploited, the vulnerability allows for complete compromise of the affected CMS instance, potentially leading to data theft, service disruption, or further lateral movement within the network. The vulnerability aligns with CWE-434 which specifically addresses "Unrestricted Upload of File with Dangerous Type" and represents a classic example of insecure file upload handling that can be leveraged for remote code execution. From an attack perspective, this vulnerability maps to multiple ATT&CK techniques including T1190 for exploitation of vulnerabilities, T1059 for command and scripting interpreter usage, and T1078 for valid accounts and T1566 for malicious file delivery.
Mitigation strategies for this vulnerability require immediate implementation of comprehensive file upload validation mechanisms that go beyond simple header inspection. Organizations should implement strict file type validation based on actual file content rather than relying solely on MIME type headers, employ proper file extension filtering, and ensure that uploaded files are stored outside the web root directory. Additionally, implementing Content Security Policy headers, disabling unnecessary file upload functionality, and conducting regular security audits of file handling processes are essential remediation steps. The fix should include proper input sanitization, comprehensive file format verification using multiple validation methods, and the implementation of secure file upload libraries that properly validate both file headers and content signatures to prevent similar bypass techniques from succeeding in the future.