CVE-2017-14925 in Tiki
Summary
by MITRE
Cross-Site Request Forgery (CSRF) vulnerability via IMG element in Tiki before 16.3, 17.x before 17.1, 12 LTS before 12.12 LTS, and 15 LTS before 15.5 LTS allows an authenticated user to edit global permissions if an administrator opens a wiki page with an IMG element, related to tiki-objectpermissions.php. For example, an attacker could assign administrator privileges to every unauthenticated user of the site.
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Analysis
by VulDB Data Team • 11/20/2019
This cross-site request forgery vulnerability exists in the Tiki wiki platform and represents a critical security flaw that allows authenticated users to manipulate global permissions through malicious image elements. The vulnerability specifically affects versions prior to 16.3, 17.1, 12 LTS 12.12 LTS, and 15 LTS 15.5 LTS, making it a widespread issue across multiple release branches. The flaw manifests when an administrator views a wiki page containing a malicious IMG element that triggers a CSRF attack against the tiki-objectpermissions.php endpoint, which handles permission management for wiki objects.
The technical mechanism of this vulnerability relies on the improper handling of CSRF tokens within the permission modification functionality. When an administrator loads a page containing a malicious IMG element, the browser automatically attempts to fetch the image resource, which triggers a request to the tiki-objectpermissions.php script. This script fails to validate that the request originated from a legitimate administrative session, instead processing the permission changes without proper authentication verification. The IMG element can be crafted to contain embedded malicious parameters that, when processed by the vulnerable system, result in unauthorized permission modifications.
The operational impact of this vulnerability is severe as it allows attackers to escalate privileges within the wiki environment. An attacker who can convince an administrator to view a malicious page could grant full administrative privileges to unauthenticated users, effectively compromising the entire wiki system. This represents a privilege escalation vulnerability that can be exploited remotely without requiring the attacker to have prior access credentials. The attack vector is particularly dangerous because it leverages the administrator's trusted session, making it difficult to detect and prevent through standard security monitoring.
This vulnerability maps to CWE-352, Cross-Site Request Forgery, which is a well-documented weakness in web application security that occurs when a web application fails to properly verify the source of requests. The attack pattern aligns with ATT&CK technique T1078.004, Valid Accounts, as it exploits legitimate administrative sessions to perform unauthorized actions. The vulnerability also demonstrates characteristics of T1548.001, Abuse of Functionality, where legitimate application functionality is misused to achieve malicious outcomes. Organizations using affected Tiki versions should implement immediate mitigations including CSRF token validation, proper request origin verification, and the implementation of Content Security Policy headers to prevent unauthorized resource loading.
The remediation strategy involves upgrading to patched versions of Tiki where CSRF protection has been properly implemented for permission modification functions. Administrators should also implement additional security controls such as verifying request origins, implementing robust CSRF token validation, and configuring proper access controls for permission management functions. The vulnerability underscores the importance of proper input validation and authentication verification in web applications, particularly for functions that modify critical system settings or user permissions. Organizations should conduct comprehensive security assessments of their Tiki installations and review all user-facing components that interact with permission management systems to prevent similar vulnerabilities from existing in other parts of their web applications.