CVE-2018-7188 in Tiki
Summary
by MITRE
An XSS vulnerability (via an SVG image) in Tiki before 18 allows an authenticated user to gain administrator privileges if an administrator opens a wiki page with a malicious SVG image, related to lib/filegals/filegallib.php.
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Analysis
by VulDB Data Team • 01/06/2020
This vulnerability represents a sophisticated cross-site scripting attack that exploits the trust relationship between users and the Tiki wiki platform. The flaw exists within the file gallery functionality where SVG images are processed, specifically in the lib/filegals/filegallib.php component. An authenticated user with limited privileges can craft a malicious SVG image that, when viewed by an administrator, triggers unauthorized privilege escalation. The vulnerability demonstrates how seemingly benign file upload capabilities can become weaponized when proper input validation and sanitization are absent.
The technical implementation of this attack relies on the inherent characteristics of SVG files which can contain embedded javascript code and other malicious payloads. When an administrator views a wiki page containing the malicious SVG image, the browser executes the embedded code within the context of the administrator's session. This creates a privilege escalation scenario where the attacker can potentially gain full administrative control over the Tiki platform. The vulnerability specifically targets the file gallery library component, indicating that the issue stems from improper handling of user-supplied SVG content during processing and rendering operations.
The operational impact of this vulnerability extends beyond simple XSS exploitation as it enables full administrative compromise of the wiki system. An attacker who can upload content to a Tiki instance can effectively take complete control of the platform, potentially accessing sensitive data, modifying content, creating new users, or even using the compromised system as a launch point for further attacks against the broader network infrastructure. This represents a critical security flaw that undermines the integrity and confidentiality of the entire wiki platform.
Mitigation strategies should focus on comprehensive input validation and sanitization of all uploaded file types, particularly SVG images. Implementing strict content security policies, disabling inline scripting in SVG files, and employing proper file type verification mechanisms are essential defensive measures. Organizations should also consider implementing web application firewalls to detect and block malicious SVG content, along with regular security audits of file upload functionalities. The vulnerability aligns with CWE-79 which describes cross-site scripting flaws, and maps to ATT&CK technique T1059.007 for script injection attacks, emphasizing the need for robust input validation and proper security controls to prevent such privilege escalation scenarios.