CVE-2018-18835 in DocCms
Summary
by MITRE
upload_template() in system/changeskin.php in DocCms 2016.5.12 allows remote attackers to execute arbitrary PHP code via a template file.
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Analysis
by VulDB Data Team • 04/07/2020
The vulnerability identified as CVE-2018-18835 resides within the DocCms content management system version 2016.5.12, specifically within the upload_template() function located in the system/changeskin.php file. This flaw represents a critical security weakness that enables remote attackers to execute arbitrary PHP code on the target system, fundamentally compromising the integrity and confidentiality of the affected environment.
The technical implementation of this vulnerability stems from insufficient input validation and sanitization within the template upload functionality. When users attempt to upload template files through the upload_template() function, the application fails to properly validate the file extensions or content, allowing malicious actors to upload PHP files containing executable code. This weakness directly maps to CWE-434, which addresses insecure file upload vulnerabilities where applications accept files without proper validation, and aligns with ATT&CK technique T1190, which covers exploiting vulnerabilities in web applications through file upload mechanisms.
The operational impact of this vulnerability is severe and multifaceted, as it provides attackers with complete control over the affected system. Once exploited, adversaries can execute arbitrary commands, potentially leading to data exfiltration, system compromise, or further lateral movement within the network. The vulnerability affects the entire web application stack, as successful exploitation allows attackers to bypass normal authentication mechanisms and directly interact with the server's file system through PHP execution capabilities. This creates a persistent threat vector that can be leveraged for extended compromise and data theft.
Mitigation strategies for CVE-2018-18835 must address both immediate remediation and long-term security hardening. The primary recommendation involves applying the official security patch released by DocCms developers, which typically includes proper input validation and file type restrictions for template uploads. Organizations should implement strict file extension filtering, reject executable file types, and employ content validation checks to prevent PHP code execution. Additionally, implementing web application firewalls with rules specifically targeting file upload attack patterns, conducting regular security assessments, and maintaining up-to-date vulnerability scanning procedures are essential defensive measures. The vulnerability demonstrates the critical importance of secure file handling practices and proper input validation in web applications, reinforcing industry standards that emphasize the need for comprehensive security controls throughout the software development lifecycle.