CVE-2018-6379 in Joomla
Summary
by MITRE
In Joomla! before 3.8.4, inadequate input filtering in the Uri class (formerly JUri) leads to an XSS vulnerability.
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Analysis
by VulDB Data Team • 02/02/2021
The vulnerability identified as CVE-2018-6379 represents a critical cross-site scripting flaw within the Joomla! content management system affecting versions prior to 3.8.4. This security weakness resides in the Uri class implementation which historically was known as JUri, demonstrating how legacy code components can harbor persistent security risks that span multiple versions. The issue emerges from insufficient sanitization of user-supplied input parameters that are processed through the URI parsing mechanism, creating an exploitable condition where malicious actors can inject harmful scripts into web applications.
The technical root cause of this vulnerability stems from inadequate input validation within the Joomla! framework's URI handling functionality. When the system processes Uniform Resource Identifier components, particularly those containing user-controllable data, the filtering mechanisms fail to properly sanitize or escape potentially malicious content. This flaw allows attackers to craft specially formatted URLs that, when processed by the application, execute arbitrary JavaScript code in the context of a victim's browser session. The vulnerability specifically affects how the system handles query parameters, fragments, and other URI components that are not adequately validated before being rendered in web pages.
The operational impact of this vulnerability extends beyond simple script execution as it provides attackers with a means to compromise user sessions, steal sensitive information, manipulate application data, and potentially escalate privileges within the Joomla powers millions of websites globally, making this vulnerability a high-value target for threat actors seeking to compromise web applications. The vulnerability can be exploited through various vectors including but not limited to malicious links shared via social media, email phishing campaigns, or direct injection into web forms that process URI data.
Mitigation strategies for CVE-2018-6379 primarily focus on immediate patching of affected Joomla! installations to version 3.8.4 or later, which contains the necessary input filtering improvements. Organizations should also implement comprehensive input validation at multiple layers of their application architecture, including web application firewalls that can detect and block suspicious URI patterns. Security monitoring should be enhanced to detect unusual traffic patterns or attempts to exploit URI-based vulnerabilities. Additionally, developers should follow secure coding practices such as implementing proper output encoding when rendering URI components and utilizing parameterized queries to prevent injection attacks. The remediation process should include thorough testing of all URI handling components and validation of input sanitization measures to ensure that similar vulnerabilities do not exist in other parts of the application codebase. Organizations should also consider implementing automated security scanning tools that can identify and alert on potential XSS vulnerabilities in their web applications, as this type of flaw often indicates broader security gaps in input validation practices that align with ATT&CK framework techniques related to command and control operations and credential access.