CVE-2018-6377 in Joomla
Summary
by MITRE
In Joomla! before 3.8.4, inadequate input filtering in com_fields leads to an XSS vulnerability in multiple field types, i.e., list, radio, and checkbox
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Analysis
by VulDB Data Team • 02/02/2021
The vulnerability identified as CVE-2018-6377 represents a critical cross-site scripting flaw discovered in Joomla! content management systems prior to version 3.8.4. This security weakness resides within the com_fields component which handles custom fields functionality in Joomla installations. The vulnerability specifically affects multiple field types including list, radio, and checkbox inputs, making it particularly dangerous as it can be exploited across various user interface elements within the Joomla admin panel and frontend applications.
The technical root cause of this vulnerability stems from insufficient input validation and sanitization mechanisms within the com_fields component. When users create or edit custom fields through the Joomla administrative interface, the system fails to properly filter malicious input data before storing it in the database or rendering it in web pages. This inadequate filtering allows attackers to inject malicious JavaScript code into field values that are subsequently executed in the browsers of unsuspecting users who view these fields. The vulnerability is particularly concerning because it affects core field types that are commonly used throughout Joomla installations, making the attack surface quite broad.
The operational impact of this vulnerability extends beyond simple data corruption or user interface disruption. An attacker who successfully exploits this XSS flaw can potentially escalate privileges, steal user sessions, manipulate content displayed to other users, or even redirect victims to malicious websites. The vulnerability affects both authenticated and unauthenticated users depending on the specific context where the malicious input is rendered. Since the flaw exists in core Joomla components that are widely deployed across numerous websites, the potential for widespread exploitation is significant. This vulnerability could be particularly devastating in enterprise environments where Joomla is used for content management and where users may have elevated privileges.
Mitigation strategies for CVE-2018-6377 primarily focus on immediate patching of affected Joomla installations to version 3.8.4 or later, which includes proper input sanitization measures. Organizations should also implement additional security layers such as web application firewalls that can detect and block suspicious input patterns, and conduct thorough security audits of custom field implementations. The vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and can be mapped to ATT&CK technique T1059.007 for script injection attacks. Administrators should also consider implementing Content Security Policy headers to limit the execution of unauthorized scripts, and regularly monitor user-generated content for malicious patterns. Regular security assessments and vulnerability scanning should be conducted to identify similar input validation weaknesses in other components of the Joomla installation.