CVE-2023-31505 in Schlix
Summary
by MITRE • 01/31/2024
An arbitrary file upload vulnerability in Schlix CMS v2.2.8-1, allows remote authenticated attackers to execute arbitrary code and obtain sensitive information via a crafted .phtml file.
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Analysis
by VulDB Data Team • 06/21/2025
The vulnerability identified as CVE-2023-31505 represents a critical arbitrary file upload flaw within Schlix CMS version 2.2.8-1 that exposes systems to remote code execution and information disclosure risks. This vulnerability specifically affects the content management system's file upload functionality, where proper input validation and file type restrictions are inadequately implemented. The flaw enables authenticated attackers to upload malicious files with the .phtml extension, which are typically used for PHP include files, thereby creating a direct pathway for code execution on the target server. The vulnerability stems from insufficient sanitization of file upload parameters and lacks proper file extension validation mechanisms that would normally prevent the upload of executable scripts or web shells.
The technical exploitation of this vulnerability occurs through the manipulation of the CMS's file upload interface where attackers can craft malicious .phtml files that contain malicious PHP code. When these files are uploaded and subsequently processed by the CMS, the server executes the embedded PHP code, allowing attackers to gain unauthorized access to system resources. This arbitrary code execution capability extends beyond simple file manipulation to encompass full system compromise, including the potential to establish persistent backdoors, escalate privileges, and exfiltrate sensitive data from the server environment. The vulnerability impacts the integrity and confidentiality of the system as attackers can manipulate uploaded files to execute arbitrary commands with the privileges of the web application user, potentially leading to complete system takeover.
From an operational perspective, this vulnerability creates significant risk for organizations utilizing Schlix CMS v2.2.8-1 as it allows authenticated attackers to leverage their existing access credentials to perform remote code execution. The impact extends beyond immediate system compromise to include potential data breaches, service disruption, and regulatory compliance violations. Attackers can use this vulnerability to deploy web shells, steal database credentials, modify content management system configurations, or establish persistent access points within the network infrastructure. The vulnerability's classification aligns with CWE-434 which specifically addresses "Unrestricted Upload of File with Dangerous Type" and demonstrates the critical nature of inadequate file validation in web applications. The ATT&CK framework categorizes this vulnerability under T1190 - Exploit Public-Facing Application and T1059 - Command and Scripting Interpreter, highlighting the exploitation techniques and post-compromise activities that attackers can perform.
Organizations should immediately implement mitigations including updating to the latest version of Schlix CMS where this vulnerability has been addressed through proper input validation and file type restrictions. The recommended approach involves implementing strict file extension validation, enforcing content type checking, and deploying web application firewalls to monitor and block suspicious file upload attempts. Additional security measures should include restricting upload permissions to minimum necessary privileges, implementing proper file naming conventions that prevent execution of uploaded files, and conducting regular security assessments of the CMS environment. System administrators should also monitor server logs for unusual file upload patterns and implement intrusion detection systems to identify potential exploitation attempts. The vulnerability demonstrates the importance of proper input validation and the principle of least privilege in web application security, emphasizing that even authenticated users should not be granted unrestricted file upload capabilities that could lead to system compromise.