CVE-2020-21322 in Feehi
Summary
by MITRE • 09/16/2021
An arbitrary file upload vulnerability in Feehi CMS v2.0.8 and below allows attackers to execute arbitrary code via a crafted PHP file.
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Analysis
by VulDB Data Team • 06/20/2023
The CVE-2020-21322 vulnerability represents a critical arbitrary file upload flaw in Feehi CMS versions 2.0.8 and earlier, constituting a severe security risk that can lead to complete system compromise. This vulnerability falls under the category of insecure file handling within web applications, specifically targeting the content management system's file upload functionality. The flaw allows malicious actors to bypass normal file validation mechanisms and upload malicious PHP files to the server, creating a persistent backdoor for unauthorized access and code execution. Such vulnerabilities are particularly dangerous because they enable attackers to gain control over the entire web application environment and potentially the underlying server infrastructure.
The technical implementation of this vulnerability stems from inadequate input validation and sanitization within the CMS's file upload handlers. Attackers can craft specially formatted PHP files with malicious payloads that are not properly filtered or rejected by the application's security controls. The vulnerability typically occurs when the application fails to properly validate file extensions, MIME types, or file contents before storing uploaded files. This weakness creates an attack surface where an unauthenticated user can upload files with extensions like .php, .phtml, or other executable formats that can be executed by the web server. The vulnerability is classified as a CWE-434: Unrestricted Upload of File with Dangerous Type, which directly maps to the ATT&CK technique T1505.003: Server Software Component, where adversaries leverage compromised web applications to deploy malicious code. The flaw demonstrates a fundamental failure in the application's security architecture, as it allows attackers to upload and execute code without proper authentication or authorization checks.
The operational impact of CVE-2020-21322 extends far beyond simple privilege escalation, potentially enabling full system compromise and persistent access to affected environments. Once an attacker successfully uploads a malicious PHP file, they can execute arbitrary commands on the server, leading to data exfiltration, service disruption, or even lateral movement within the network. The vulnerability can be exploited to establish reverse shells, install additional malware, or manipulate the CMS's database and user accounts. Organizations running affected versions of Feehi CMS face significant risk of data breaches, as attackers can access sensitive information stored within the application, including user credentials, personal data, and business-critical information. The persistent nature of this vulnerability means that once exploited, the attacker maintains access even after system restarts, unless the malicious file is manually removed or the application is patched. This type of vulnerability directly impacts the CIA triad by compromising confidentiality, integrity, and availability of the affected systems.
Mitigation strategies for CVE-2020-21322 should prioritize immediate patching of the affected Feehi CMS versions to the latest secure releases. Organizations must implement robust file upload validation controls including strict file extension filtering, MIME type verification, and content inspection to prevent execution of malicious files. The implementation of proper access controls and authentication mechanisms can help reduce the attack surface, while regular security audits and penetration testing should identify similar vulnerabilities in other applications. Network-based mitigations such as web application firewalls can provide additional protection layers, though they should not be considered a complete solution. Security teams should also establish monitoring protocols to detect suspicious file upload activities and implement proper incident response procedures to quickly address exploitation attempts. The vulnerability highlights the importance of maintaining up-to-date software versions and implementing defense-in-depth strategies to protect against similar attacks. Organizations should also consider implementing file integrity monitoring solutions and regular security assessments to identify and remediate similar vulnerabilities across their entire infrastructure. The remediation process must include comprehensive testing to ensure that the patch does not introduce compatibility issues while maintaining the application's core functionality and security posture.