CVE-2019-17188 in FecMall
Summary
by MITRE
An unrestricted file upload vulnerability was discovered in catalog/productinfo/imageupload in Fecshop FecMall 2.3.4. An attacker can bypass a front-end restriction and upload PHP code to the webserver, by providing image data and the image/jpeg content type, with a .php extension. This occurs because the code relies on the getimagesize function.
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Analysis
by VulDB Data Team • 01/03/2024
The vulnerability CVE-2019-17188 represents a critical unrestricted file upload flaw in the Fecshop FecMall e-commerce platform version 2.3.4. This security weakness resides within the catalog/productinfo/imageupload endpoint, where the application fails to properly validate file types during the upload process. The vulnerability stems from the application's reliance on the getimagesize function for image validation, which creates a fundamental security gap that attackers can exploit to bypass client-side restrictions and execute malicious code on the target server.
The technical implementation of this vulnerability demonstrates a classic case of improper input validation and insufficient file type verification. When an attacker submits a file with a .php extension but includes image/jpeg content type headers, the system's reliance on getimagesize for validation becomes problematic because this function only checks the image header data and does not verify the actual file extension or content. This approach creates a false sense of security as the application assumes that any file passing the getimagesize check is legitimate, despite the file extension being manipulated to bypass server-side restrictions. The vulnerability specifically affects the image upload functionality within the product information management system, which is a core component of any e-commerce platform.
The operational impact of this vulnerability is severe and multifaceted, potentially allowing attackers to achieve remote code execution on the affected web server. An attacker who successfully exploits this vulnerability can upload malicious PHP scripts that will execute with the privileges of the web server process, typically resulting in full server compromise. This could lead to data theft, service disruption, unauthorized access to customer information, and potential lateral movement within the network infrastructure. The attack vector is particularly concerning as it requires minimal privileges and leverages the legitimate image upload functionality, making it difficult to detect through traditional security monitoring. This vulnerability aligns with CWE-434 which specifically addresses "Unrestricted Upload of File with Dangerous Type" and represents a direct violation of the principle of least privilege in web application security.
The exploitation of this vulnerability follows established attack patterns that align with the MITRE ATT&CK framework, particularly under the technique T1190 "Exploit Public-Facing Application" and T1059.007 "Command and Scripting Interpreter: PHP". The attack begins with reconnaissance to identify the vulnerable endpoint, followed by crafting a malicious payload that appears to be a legitimate image file but contains PHP shell code. The attacker can then upload this file and execute it through the web browser, potentially gaining a reverse shell or establishing persistent access to the compromised system. Organizations using Fecshop FecMall 2.3.4 should immediately implement multiple layers of defense including input validation, file type verification, and proper file extension checking to prevent such attacks from succeeding.
Mitigation strategies for this vulnerability should include immediate patching of the affected Fecshop FecMall version to the latest available release that addresses this specific flaw. Organizations should also implement robust file validation mechanisms that check both the file extension and MIME type against a whitelist of approved formats, while ensuring that uploaded files are stored outside the web root directory. The application should employ strict file type validation using multiple verification methods rather than relying solely on getimagesize or similar functions. Additionally, implementing proper access controls and monitoring for unusual file upload activities can help detect potential exploitation attempts. Security configurations should enforce proper file permissions and ensure that uploaded files cannot be executed directly by the web server. These measures align with industry best practices and security standards including OWASP Top 10 and NIST Cybersecurity Framework recommendations for preventing file upload vulnerabilities.