CVE-2021-37372 in Online Student Admission System
Summary
by MITRE • 10/26/2021
Online Student Admission System 1.0 is affected by an insecure file upload vulnerability. A low privileged user can upload malicious PHP files by updating their profile image to gain remote code execution.
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Analysis
by VulDB Data Team • 10/30/2021
The Online Student Admission System version 1.0 contains a critical insecure file upload vulnerability that allows low privilege users to execute arbitrary code on the target system. This vulnerability stems from inadequate input validation and file type checking mechanisms within the profile image upload functionality. The flaw enables attackers to bypass security restrictions and upload malicious php files that can be executed on the server, creating a persistent backdoor for unauthorized access.
This vulnerability directly maps to CWE-434 which defines insecure file upload conditions where applications fail to properly validate file types and contents before storing them on the server. The system's failure to implement proper file extension validation, content type checking, or file analysis allows attackers to upload php scripts that can be executed as part of the web application's request processing. The vulnerability exists because the application trusts user-provided file names and types without proper sanitization or verification.
The operational impact of this vulnerability is severe as it provides attackers with complete remote code execution capabilities within the application's context. Once a malicious php file is successfully uploaded and executed, an attacker can perform various malicious activities including data exfiltration, privilege escalation, lateral movement within the network, and persistent access to the system. The low privilege user can leverage this vulnerability to escalate their privileges and gain administrative control over the entire admission system.
From an attack perspective, this vulnerability aligns with ATT&CK technique T1505.003 which involves the use of web shell deployment for maintaining access. The attacker can upload a php web shell that provides command execution capabilities through web requests. This vulnerability also relates to T1078 which covers valid accounts usage, as the attacker can leverage existing user accounts to upload malicious files without requiring additional authentication. The system's lack of proper file upload restrictions creates an attack surface that can be exploited by threat actors at various maturity levels.
The recommended mitigation strategies include implementing strict file type validation that checks both file extensions and MIME types against a whitelist of allowed formats. The system should perform content-based validation by analyzing file headers and signatures rather than relying solely on file extensions. Additional security measures should include storing uploaded files outside the web root directory, implementing proper file naming conventions that prevent path traversal attacks, and adding proper access controls to prevent unauthorized execution of uploaded files. Regular security testing including penetration testing and static code analysis should be conducted to identify similar vulnerabilities in the application's codebase.