CVE-2017-16633 in Joomla
Summary
by MITRE
In Joomla! before 3.8.2, a logic bug in com_fields exposed read-only information about a site's custom fields to unauthorized users.
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Analysis
by VulDB Data Team • 01/23/2021
The vulnerability CVE-2017-16633 represents a critical access control flaw in Joomla! content management systems prior to version 3.8.2. This issue stems from a logic bug within the com_fields component that governs custom field functionality in Joomla installations. The flaw allows unauthorized users to access read-only information about custom fields that should typically be restricted to authorized personnel only. The vulnerability specifically affects the component responsible for managing custom fields within Joomla's administrative interface, creating an unintended information disclosure channel that bypasses normal access controls.
The technical implementation of this vulnerability involves a flaw in the access control logic that determines which users can view custom field data. When users attempt to access custom field information through the com_fields component, the system fails to properly validate user permissions before returning field metadata. This logic error creates a scenario where any authenticated user, regardless of their role or permissions level, can retrieve information about custom fields that contain sensitive configuration data or field definitions. The flaw operates at the application level and does not require special privileges or advanced exploitation techniques to manifest.
The operational impact of this vulnerability extends beyond simple information disclosure, as it provides attackers with insights into the site's custom field structure and potentially reveals sensitive metadata about the Joomla installation. Attackers can leverage this information to better understand the site's configuration, identify potential attack vectors, and plan more sophisticated exploitation attempts. The exposure of custom field information may include field names, data types, and structural information that could aid in crafting targeted attacks against other components or modules within the Joomla ecosystem. This vulnerability particularly affects sites that utilize extensive custom field configurations for content management, as the exposed information could reveal organizational structure or business logic embedded within the field definitions.
Organizations affected by this vulnerability should immediately upgrade to Joomla! version 3.8.2 or later, which contains the necessary patches to address the access control logic flaw. The fix implemented by the Joomla development team corrects the validation routine within the com_fields component to properly enforce user permissions before exposing field information. Security administrators should also conduct comprehensive audits of their custom field configurations to identify any potential misuse of the exposed information and implement additional monitoring for unauthorized access attempts. This vulnerability aligns with CWE-284 which addresses improper access control issues, and may be categorized under ATT&CK technique T1213 for data from information repositories, as it involves unauthorized access to stored data within the application's information system. The remediation process should include verifying that all custom field access controls are properly enforced and that no additional bypass mechanisms exist within the Joomla framework's permission system.