CVE-2019-9181 in SchoolCMS
Summary
by MITRE
SchoolCMS version 2.3.1 allows file upload via the logo upload feature at admin.php?m=admin&c=site&a=save by using the .jpg extension, changing the Content-Type to image/php, and placing PHP code after the JPEG data. This ultimately allows execution of arbitrary PHP code.
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Analysis
by VulDB Data Team • 07/19/2023
The vulnerability identified as CVE-2019-9181 resides within SchoolCMS version 2.3.1, specifically targeting the administrative logo upload functionality accessible through the URL path admin.php?m=admin&c=site&a=save. This represents a critical security flaw that demonstrates poor input validation and file type verification mechanisms within the content management system. The vulnerability operates through a sophisticated technique that exploits the trust placed in file extensions while bypassing traditional security measures that rely solely on MIME type checking. The attack vector leverages the fact that many web applications accept files with .jpg extensions while performing content-type validation that may be easily manipulated or bypassed through crafted requests.
The technical exploitation of this vulnerability occurs through a multi-layered approach that combines file extension manipulation with content-type header forgery. Attackers can upload a file with a .jpg extension while simultaneously altering the Content-Type header to image/php, effectively deceiving the server into treating the file as a PHP script rather than a standard image. This technique exploits the fundamental weakness in file validation where the system accepts the extension without proper binary content verification. The malicious PHP code is strategically placed after the legitimate JPEG data, allowing the uploaded file to function as both a valid image for display purposes and an executable PHP script for code execution. This dual-purpose file structure represents a classic example of file upload vulnerability exploitation that aligns with CWE-434, which specifically addresses insecure file upload handling in web applications.
The operational impact of this vulnerability extends far beyond simple unauthorized file placement, as it provides attackers with complete arbitrary code execution capabilities within the target system. Successful exploitation allows malicious actors to execute arbitrary PHP commands with the privileges of the web server process, potentially leading to full system compromise, data exfiltration, or the establishment of persistent backdoors. This vulnerability enables attackers to bypass traditional security controls and gain unauthorized access to the administrative interface and underlying system resources. The implications are particularly severe for educational institutions using SchoolCMS, as the compromise could result in the exposure of sensitive student and staff information, disruption of educational services, and potential legal ramifications under data protection regulations.
Mitigation strategies for CVE-2019-9181 require a comprehensive approach that addresses both the immediate vulnerability and broader security architecture concerns. Organizations should implement strict file validation mechanisms that verify both file extensions and actual file content rather than relying solely on MIME type headers or extension-based checks. The recommended solution involves implementing robust file type verification through binary signature checking, rejecting files with suspicious content patterns, and ensuring that uploaded files are stored outside the web root directory. Additionally, implementing proper access controls and privilege separation ensures that even if an attacker successfully uploads a malicious file, the execution scope remains limited. This vulnerability demonstrates the importance of following secure coding practices as outlined in the OWASP Top Ten and aligns with ATT&CK technique T1190 for exploiting web application vulnerabilities, emphasizing the need for comprehensive input validation and file handling security measures across all web applications.