CVE-2020-19672 in B2B2C Multi-Business Basic
Summary
by MITRE • 10/04/2020
Niushop B2B2C Multi-business basic version V1.11, can bypass the administrator to obtain the background upload interface, through parameter upload, bypass the getimagesize function, upload php file, getshell.
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Analysis
by VulDB Data Team • 11/15/2020
The vulnerability identified as CVE-2020-19672 affects Niushop B2B2C Multi-business basic version V1.11, representing a critical security flaw that allows unauthorized users to bypass administrative access controls and gain unauthorized shell access to the system. This vulnerability stems from insufficient input validation and access control mechanisms within the application's file upload functionality, creating a pathway for malicious actors to escalate their privileges and execute arbitrary code on the target server.
The technical exploitation of this vulnerability involves a sophisticated bypass technique targeting the administrator's backend upload interface. Attackers can manipulate the upload parameters to circumvent the getimagesize function, which is typically used to validate image files and prevent execution of malicious code. This function serves as a crucial security control that verifies file types by examining image headers, but the vulnerability allows attackers to bypass this validation entirely. Through careful parameter manipulation, attackers can upload php files that contain malicious code, effectively creating a backdoor that provides remote code execution capabilities.
The operational impact of this vulnerability is severe and multifaceted, as it enables complete system compromise and persistent access for attackers. Once successful, the vulnerability allows threat actors to execute arbitrary commands on the server, potentially leading to data exfiltration, system enumeration, privilege escalation, and establishment of persistent footholds within the network. The vulnerability affects the entire application ecosystem, as successful exploitation can result in complete compromise of the web application and underlying server infrastructure. Organizations relying on this version of Niushop B2B2C face significant risks including potential data breaches, service disruption, and regulatory compliance violations.
This vulnerability aligns with CWE-434, which addresses insecure file upload vulnerabilities where applications accept files without proper validation, and corresponds to ATT&CK technique T1190 for exploiting vulnerabilities in web applications. The attack surface is particularly concerning as it targets the administrative interface, which typically requires elevated privileges and contains sensitive operations. The bypass of getimagesize function demonstrates a lack of proper input sanitization and validation, which are fundamental security controls recommended by OWASP and NIST cybersecurity frameworks. Organizations should implement immediate mitigations including input validation, file type restrictions, and access control enforcement to prevent exploitation of this vulnerability.
The mitigation strategy should focus on implementing robust file validation mechanisms that do not rely solely on file extension checks or header verification. Security controls should include mandatory file type validation using multiple verification methods, restriction of upload directories, implementation of proper access controls, and regular security audits. Additionally, organizations should consider deploying web application firewalls and implementing network segmentation to limit the potential impact of successful exploitation. The vulnerability underscores the importance of proper security testing and validation of file upload functionalities, particularly in administrative interfaces where privileged access is involved.