CVE-2017-14924 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 gain administrator privileges if an administrator opens a wiki page with an IMG element, related to tiki-assignuser.php.
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Analysis
by VulDB Data Team • 11/20/2019
This cross-site request forgery vulnerability exists within the Tiki wiki platform affecting multiple release versions including 16.3, 17.1, 12 LTS 12.12 LTS, and 15 LTS 15.5 LTS. The flaw specifically manifests when an authenticated user crafts a malicious wiki page containing an IMG element that references a vulnerable endpoint. This vulnerability falls under CWE-352 which categorizes cross-site request forgery flaws as a critical security weakness where an attacker can trick a victim into performing actions they did not intend. The vulnerability is particularly dangerous because it leverages the IMG element's ability to make HTTP requests without requiring user interaction, making it a sophisticated attack vector that bypasses traditional CSRF protection mechanisms. The vulnerability is directly related to the tiki-assignuser.php endpoint which handles user assignment operations within the wiki platform.
The technical exploitation occurs when an administrator user opens a wiki page that contains a malicious IMG element pointing to the vulnerable tiki-assignuser.php script. This script processes user assignment requests without proper CSRF token validation, allowing an attacker to manipulate the target user's permissions. The IMG element's attribute handling creates a scenario where the browser automatically requests the malicious URL when rendering the page, effectively executing the CSRF attack without requiring the administrator to click any links or buttons. This particular implementation bypasses standard CSRF protection mechanisms because the IMG element's src attribute is processed automatically by the browser's rendering engine, making it difficult to detect and prevent through conventional means. The vulnerability is classified as a server-side request forgery issue where the server processes the request without validating the request origin or user intent.
The operational impact of this vulnerability is severe as it allows an attacker with basic user privileges to escalate their access to administrator level permissions. Once an administrator opens a maliciously crafted wiki page, the attacker can potentially gain complete control over the wiki platform, including the ability to modify content, add users, delete data, and access sensitive information. This privilege escalation capability directly violates the principle of least privilege and can lead to complete system compromise. The attack requires minimal user interaction beyond simply viewing a wiki page, making it particularly dangerous in environments where administrators frequently access external content or collaborate with untrusted users. The vulnerability also demonstrates poor input validation practices and insufficient request origin verification, which are fundamental security requirements according to OWASP Top Ten and NIST cybersecurity guidelines. This type of vulnerability aligns with ATT&CK technique T1078 which covers legitimate credentials use for persistence and privilege escalation.
The recommended mitigations for this vulnerability include implementing robust CSRF token validation mechanisms within the tiki-assignuser.php endpoint, ensuring that all user assignment operations require proper authentication tokens that are verified against the requesting user's session. Organizations should also implement Content Security Policy headers to restrict the sources from which IMG elements can load content, particularly preventing requests to internal administrative endpoints. Additionally, the Tiki platform should be updated to versions that contain proper CSRF protection mechanisms, as the vulnerability has been addressed in subsequent releases. Regular security audits should include verification of all endpoints that handle user privilege changes, ensuring that proper validation occurs regardless of the request method or element type used to trigger the operation. The implementation of proper session management and request origin verification should be enforced across all administrative functions to prevent similar vulnerabilities from occurring in the future.