CVE-2017-11326 in Tilde
Summary
by MITRE
An issue was discovered in Tilde CMS 1.0.1. It is possible to bypass the implemented restrictions on arbitrary file upload via a filename.+php manipulation.
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Analysis
by VulDB Data Team • 10/31/2019
The vulnerability identified as CVE-2017-11326 resides within Tilde CMS version 1.0.1, representing a critical security flaw that undermines the application's file upload validation mechanisms. This weakness allows malicious actors to circumvent intended restrictions designed to prevent the upload of potentially harmful files, specifically targeting the prevention of php script execution within the web application's file system. The vulnerability stems from insufficient input validation and sanitization of filename parameters during the file upload process, creating an exploitable pathway for unauthorized code execution.
The technical exploitation of this vulnerability occurs through a filename manipulation technique that leverages the CMS's inadequate filtering of file extensions and naming conventions. Attackers can append or modify the .php extension within the filename to bypass the security checks, effectively allowing them to upload malicious php files that would otherwise be rejected. This bypass mechanism operates at the application layer, where the CMS fails to properly validate or sanitize the filename before processing the upload request. The flaw aligns with CWE-434, which describes the weakness of allowing untrusted data to be uploaded to a web server, and specifically relates to CWE-22, concerning path traversal vulnerabilities that can be exploited through improper filename handling. The vulnerability demonstrates a classic case of insufficient input validation that permits malicious file types to be accepted and executed within the target environment.
The operational impact of this vulnerability is severe and far-reaching, as it provides attackers with a direct pathway to execute arbitrary code on the affected server. Successful exploitation could lead to complete system compromise, allowing threat actors to gain unauthorized access to sensitive data, install backdoors, or deploy additional malware. The vulnerability affects the integrity and confidentiality of the entire CMS environment, potentially enabling attackers to escalate privileges and establish persistent access. From an ATT&CK framework perspective, this vulnerability maps to T1190 (Exploit Public-Facing Application) and T1059.007 (Command and Scripting Interpreter: PHP), demonstrating how attackers can leverage web application flaws to achieve remote code execution. The implications extend beyond immediate system compromise, as the vulnerability could be used to establish a foothold for further network infiltration and lateral movement within the affected organization's infrastructure.
Mitigation strategies for this vulnerability must address both the immediate security gap and implement comprehensive defensive measures. Organizations should immediately update to a patched version of Tilde CMS that properly validates and sanitizes all file upload parameters, ensuring that filename extensions are strictly validated against a whitelist of allowed formats. The implementation of robust input validation mechanisms, including proper sanitization of filenames and enforcement of strict file type checking, is essential to prevent similar vulnerabilities from occurring. Network-based solutions such as web application firewalls should be configured to monitor and block suspicious file upload patterns, while application-level defenses should include proper file extension validation, content type checking, and secure file storage practices. Additionally, system administrators should implement principle of least privilege access controls and conduct regular security assessments to identify and remediate similar vulnerabilities. The vulnerability serves as a reminder of the critical importance of proper input validation and the potential consequences of inadequate security controls in web applications, emphasizing the need for comprehensive security testing and continuous monitoring to protect against evolving threats.