CVE-2018-6464 in Simditor
Summary
by MITRE
Simditor v2.3.11 allows XSS via crafted use of svg/onload=alert in a TEXTAREA element, as demonstrated by Firefox 54.0.1.
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Analysis
by VulDB Data Team • 12/31/2019
The vulnerability identified as CVE-2018-6464 represents a cross-site scripting flaw in Simditor version 2.3.11, a rich text editor component widely used in web applications. This issue specifically manifests when the editor processes user input containing malicious svg/onload=alert payloads within TEXTAREA elements, creating a persistent security risk that can be exploited across different browser environments including Firefox 54.0.1. The vulnerability stems from inadequate input sanitization and validation mechanisms within the editor's processing pipeline, allowing malicious code to bypass security controls and execute in the context of the victim's browser session.
The technical flaw resides in the editor's failure to properly sanitize or escape SVG elements when they contain onload attributes or similar event handlers within text input fields. When a user submits content containing crafted SVG code with onload handlers, the editor processes this input without sufficient validation, leading to code injection that can execute arbitrary JavaScript in the victim's browser. This represents a classic XSS vulnerability where the attack vector leverages the inherent capabilities of HTML elements to execute scripts when certain conditions are met. The vulnerability specifically targets the TEXTAREA element processing logic, where the editor fails to strip or neutralize potentially malicious SVG code that could be embedded within user-generated content. The issue is classified under CWE-79 as a failure to sanitize or escape special characters, and more specifically as a cross-site scripting vulnerability that allows execution of arbitrary web scripts in the victim's browser.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform a range of malicious activities including session hijacking, data theft, credential harvesting, and redirection to malicious sites. When exploited, the vulnerability allows attackers to inject malicious code that can persist across user sessions, potentially compromising multiple users who interact with the affected application. The vulnerability is particularly concerning because it can be triggered through normal user interaction with the text editor, making it difficult to detect and prevent through traditional security measures. The attack can be executed by simply embedding the malicious payload within a text input field, making it accessible to both authenticated and unauthenticated users who have access to the editor interface. This vulnerability affects the integrity of user data and application security, potentially leading to complete compromise of user sessions and unauthorized access to sensitive information.
Mitigation strategies for CVE-2018-6464 should focus on implementing comprehensive input validation and sanitization mechanisms within the Simditor editor. Organizations should immediately upgrade to a patched version of the editor that properly sanitizes SVG elements and prevents execution of inline event handlers. The recommended approach involves implementing a robust content security policy that restricts the execution of inline scripts and restricts the use of dangerous attributes like onload. Additionally, developers should implement proper HTML escaping and sanitization routines that remove or neutralize potentially malicious SVG code before processing user input. The solution should align with ATT&CK framework techniques such as T1203 (Exploitation for Credential Access) and T1059 (Command and Scripting Interpreter) by preventing the execution of malicious code through input fields. Organizations should also consider implementing web application firewalls that can detect and block suspicious SVG payloads, while maintaining regular security audits to identify similar vulnerabilities in other components of their web applications. The fix should ensure that all user-generated content is properly validated against a whitelist of safe characters and elements, preventing the injection of potentially harmful code that could be executed in the context of legitimate user sessions.