CVE-2018-18909 in xhEditor
Summary
by MITRE
xhEditor 1.2.2 allows XSS via JavaScript code in the SRC attribute of an IFRAME element within the editor's source-code view.
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Analysis
by VulDB Data Team • 06/04/2023
The vulnerability identified as CVE-2018-18909 affects xhEditor version 1.2.2, a rich text editor component commonly used in web applications for content management and user-generated content processing. This issue represents a cross-site scripting vulnerability that specifically targets the editor's source-code view functionality, where users can directly manipulate HTML code. The flaw manifests when JavaScript code is embedded within the src attribute of an iframe element, creating a potential attack vector that could compromise user sessions and execute malicious scripts in the context of the vulnerable application.
The technical implementation of this vulnerability stems from inadequate input sanitization and output encoding within the editor's source view processing mechanism. When users input HTML code containing iframe elements with javascript: URIs in the src attribute, the editor fails to properly validate or sanitize these inputs before rendering them in the user interface. This lack of proper sanitization allows malicious payloads to persist and execute when the HTML is subsequently rendered, as the editor does not adequately distinguish between legitimate and malicious content within the source code view. The vulnerability specifically exploits the trust relationship between the editor and the rendered content, where the editor assumes that source code input is safe without proper validation.
The operational impact of this vulnerability extends beyond simple script execution, as it enables attackers to perform session hijacking, data exfiltration, and other malicious activities that could compromise user accounts and sensitive information. An attacker could craft malicious iframe elements that, when viewed by other users, would execute scripts that steal cookies, redirect users to phishing sites, or inject additional malicious content into the application. The vulnerability is particularly dangerous in environments where multiple users interact with the same content management system, as a single compromised input could affect numerous users. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws in web applications.
Mitigation strategies for this vulnerability require immediate implementation of input validation and output encoding measures within the xhEditor component. Organizations should ensure that all user-supplied content is properly sanitized before being processed or rendered, with particular attention to iframe src attributes that may contain javascript: URIs. The recommended approach involves implementing a whitelist-based validation system that only allows specific, safe protocols and domains in iframe sources while rejecting any javascript: or data: URIs. Additionally, implementing proper content security policies can provide an additional layer of defense by restricting script execution and limiting the potential impact of successful attacks. Security teams should also consider upgrading to newer versions of xhEditor if available, as this vulnerability likely affects other components within the same codebase that may share similar sanitization issues. This vulnerability aligns with ATT&CK technique T1566 which covers social engineering tactics involving malicious content delivery through web interfaces.