CVE-2017-8085 in Exponent
Summary
by MITRE
In Exponent CMS before 2.4.1 Patch #5, XSS in elFinder is possible in framework/modules/file/connector/elfinder.php.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/02/2022
The vulnerability identified as CVE-2017-8085 affects Exponent CMS versions prior to 2.4.1 Patch #5, specifically targeting the elFinder file manager component. This issue resides within the framework/modules/file/connector/elfinder.php file, which serves as the backend connector for the elFinder file browsing interface. The vulnerability represents a cross-site scripting flaw that allows remote attackers to inject malicious scripts into the web application, potentially compromising user sessions and data integrity. The flaw occurs due to insufficient input validation and output sanitization within the file management connector, creating an attack vector that can be exploited through crafted user input parameters.
The technical implementation of this vulnerability stems from inadequate sanitization of user-supplied data within the elFinder connector module. When users interact with file management functions through the CMS interface, the application fails to properly escape or filter special characters in file names, directory paths, or other parameters passed to the elFinder component. This lack of proper input validation creates a condition where malicious payloads can be executed in the context of other users' browsers. The vulnerability is classified as a classic XSS flaw under CWE-79, which specifically addresses cross-site scripting vulnerabilities in software applications. Attackers can leverage this weakness to execute arbitrary JavaScript code, potentially leading to session hijacking, credential theft, or redirection to malicious sites.
The operational impact of CVE-2017-8085 extends beyond simple script execution, as it can facilitate more sophisticated attacks within the compromised CMS environment. An attacker who successfully exploits this vulnerability can manipulate file operations, potentially uploading malicious files or altering existing content through the file manager interface. The attack surface is particularly concerning given that elFinder is a core component of the file management system, meaning that successful exploitation could lead to complete compromise of the content management infrastructure. This vulnerability aligns with ATT&CK technique T1213.002, which involves data from information repositories, as it allows unauthorized access to file system resources through web-based interfaces. The flaw can be exploited through various attack vectors including web browser interactions, file uploads, or even through social engineering techniques that prompt users to click malicious links within the CMS interface.
Mitigation strategies for CVE-2017-8085 primarily focus on immediate patch application and input validation improvements. Organizations should prioritize upgrading to Exponent CMS version 2.4.1 Patch #5 or later, which includes the necessary security fixes for the elFinder component. Beyond patching, administrators should implement additional security measures including comprehensive input validation, output encoding, and regular security audits of file management interfaces. The implementation of Content Security Policy (CSP) headers can provide additional protection against XSS attacks by restricting script execution and limiting the sources from which scripts can be loaded. Security monitoring should include detection of suspicious file operations and unusual user behavior patterns within the file management system, as these activities may indicate exploitation attempts. The vulnerability demonstrates the importance of secure coding practices and proper input sanitization, particularly for components that handle user-supplied data in web applications. Organizations should also consider implementing web application firewalls and regular penetration testing to identify similar vulnerabilities in their CMS infrastructure and other web applications.