CVE-2017-15876 in GPWeb
Summary
by MITRE
Unrestricted File Upload vulnerability in GPWeb 8.4.61 allows remote authenticated users to upload any type of file, including a PHP shell.
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Analysis
by VulDB Data Team • 12/16/2019
The CVE-2017-15876 vulnerability represents a critical unrestricted file upload flaw in GPWeb version 8.4.61 that enables remote authenticated attackers to bypass security controls and upload malicious files to the target system. This vulnerability falls under the category of insecure file handling and represents a severe security weakness that can lead to complete system compromise. The vulnerability exists due to insufficient validation and sanitization of file uploads, allowing attackers to upload files with potentially harmful extensions or content without proper authorization. The impact of this vulnerability extends beyond simple file upload capabilities as it provides attackers with a potential pathway to execute arbitrary code on the affected system.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the GPWeb application's file upload functionality. When authenticated users submit files through the web interface, the system fails to properly verify file types, extensions, or content signatures before storing the uploaded files. This lack of proper validation allows attackers to upload PHP shell scripts or other malicious executables that can be executed within the web server context. The vulnerability is particularly dangerous because it operates within the context of authenticated users, meaning that an attacker who has already gained valid credentials can leverage this weakness to escalate privileges and gain deeper access to the underlying system infrastructure.
The operational impact of CVE-2017-15876 is significant and multifaceted, potentially leading to complete system compromise and unauthorized access to sensitive data. Attackers can upload web shells that provide persistent backdoor access, allowing them to execute commands, steal data, or establish further footholds within the network. The vulnerability creates a persistent threat vector that can be exploited repeatedly, as the uploaded malicious files remain on the system until manually removed. This weakness also enables attackers to perform reconnaissance activities, escalate privileges, and potentially move laterally within the network infrastructure. The attack surface expands significantly when considering that the vulnerability affects a web-based application, making it accessible over the network and potentially exploitable by attackers with minimal local access.
Security professionals should consider this vulnerability in relation to established frameworks such as CWE-434 which specifically addresses insecure file upload vulnerabilities, and the ATT&CK framework's T1190 technique for exploiting vulnerabilities in web applications. Organizations should implement comprehensive mitigation strategies including strict file type validation, proper file extension filtering, and content-based file analysis. The recommended approach includes implementing whitelisting of acceptable file types, removing executable permissions from upload directories, and conducting regular security assessments to identify and remediate similar vulnerabilities. Additionally, organizations should enforce principle of least privilege access controls and maintain up-to-date security patches to prevent exploitation of known vulnerabilities in web applications.