CVE-2017-14718 in WordPress
Summary
by MITRE
Before version 4.8.2, WordPress was susceptible to a Cross-Site Scripting attack in the link modal via a javascript: or data: URL.
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Analysis
by VulDB Data Team • 01/14/2021
The vulnerability identified as CVE-2017-14718 represents a critical cross-site scripting weakness discovered in WordPress versions prior to 4.8.2. This flaw existed within the link modal functionality of the content management system, creating an avenue for malicious actors to inject harmful scripts into web pages viewed by other users. The vulnerability specifically targeted the handling of javascript: and data: URLs within the WordPress editor interface, where user input was not properly sanitized before being rendered in the browser environment.
The technical nature of this vulnerability stems from insufficient input validation and output encoding mechanisms within WordPress's link modal component. When users attempted to insert links containing javascript: or data: protocols, the system failed to adequately filter these dangerous URL schemes, allowing attackers to embed malicious scripts that would execute in the context of other users' browsers. This represents a classic XSS attack vector where the attacker crafts malicious input that gets stored and subsequently executed without proper sanitization. The vulnerability operates under CWE-79 which categorizes cross-site scripting flaws as weaknesses in input validation and output encoding, specifically targeting the improper handling of untrusted data in web applications.
The operational impact of CVE-2017-14718 extends beyond simple script injection, as it could enable attackers to perform various malicious activities including session hijacking, credential theft, and redirection to malicious websites. An attacker could craft a link containing malicious javascript code that would execute whenever a victim viewed the page containing the compromised link, potentially stealing cookies, modifying content, or redirecting users to phishing sites. The vulnerability was particularly dangerous because it existed within the core WordPress editor interface, meaning that any user with sufficient privileges to edit content could potentially exploit this weakness, making it a significant threat to WordPress installations that had not yet been updated to version 4.8.2 or later.
Security practitioners should recognize this vulnerability as part of the broader ATT&CK framework under the technique of T1059.007 for command and scripting interpreter, specifically targeting web shells and script injection methods. The remediation strategy involves immediate updating of WordPress installations to version 4.8.2 or later, which included proper input sanitization for javascript: and data: URLs. Additional mitigations include implementing content security policies, using web application firewalls, and conducting regular security audits of WordPress installations. Organizations should also consider implementing proper access controls and user privilege management to limit who can modify content within the WordPress environment, reducing the attack surface for such vulnerabilities. The vulnerability demonstrates the critical importance of keeping content management systems updated and highlights the necessity of robust input validation mechanisms in web applications to prevent exploitation of XSS vulnerabilities.