CVE-2020-19302 in vaeThink
Summary
by MITRE • 08/04/2021
An arbitrary file upload vulnerability in the avatar upload function of vaeThink v1.0.1 allows attackers to open a webshell via changing uploaded file suffixes to ".php".
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Analysis
by VulDB Data Team • 08/07/2021
The CVE-2020-19302 vulnerability represents a critical arbitrary file upload flaw within the vaeThink content management system version 1.0.1, specifically affecting the avatar upload functionality. This vulnerability stems from insufficient input validation and file extension checking mechanisms that fail to properly sanitize user-supplied file names during the upload process. The flaw enables malicious actors to bypass security controls by renaming malicious payload files with php extensions, effectively allowing remote code execution through webshell deployment.
This vulnerability maps directly to CWE-434, which describes insecure file upload vulnerabilities where applications fail to validate file types or restrict file extensions properly. The technical implementation flaw occurs when the application accepts user-provided filenames without adequate sanitization, allowing attackers to manipulate the file extension from legitimate formats to .php, thereby executing malicious code on the target server. The vulnerability exists at the application layer where user input validation is insufficient to prevent malicious file name manipulation.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with persistent remote code execution capabilities on the affected server. Once an attacker successfully uploads a malicious php file, they can establish a webshell that allows them to execute arbitrary commands, escalate privileges, access sensitive data, and maintain persistent access to the compromised system. This vulnerability can be exploited through various attack vectors including social engineering, automated scanning, or by leveraging other initial access points, making it particularly dangerous in environments where the application is publicly accessible.
Mitigation strategies for CVE-2020-19302 should include immediate patching of the vaeThink application to version 1.0.2 or later, which contains the necessary fixes for file upload validation. Organizations should implement comprehensive file validation mechanisms that reject files with potentially dangerous extensions, enforce strict file type checking, and store uploaded files in non-executable directories. Additional defensive measures include implementing proper input sanitization, using random file name generation, implementing Content Security Policy headers, and conducting regular security assessments. This vulnerability aligns with ATT&CK technique T1505.003 for server-side web shell deployment and T1078 for valid accounts usage, emphasizing the need for layered security approaches to prevent exploitation and maintain system integrity.