CVE-2015-5057 in Broken Link Checker Plugin
Summary
by MITRE
Cross-site scripting (XSS) vulnerability exists in the Wordpress admin panel when the Broken Link Checker plugin before 1.10.9 is installed.
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Analysis
by VulDB Data Team • 11/08/2019
The CVE-2015-5057 vulnerability represents a critical cross-site scripting flaw discovered in the WordPress ecosystem, specifically affecting the Broken Link Checker plugin version 1.10.8 and earlier. This vulnerability manifests within the WordPress admin panel environment, creating a dangerous attack surface where malicious actors can exploit the XSS weakness to execute arbitrary scripts in the context of authenticated admin sessions. The flaw stems from inadequate input validation and output sanitization mechanisms within the plugin's handling of user-supplied data, particularly when processing broken link information and displaying it within the administrative interface.
The technical implementation of this vulnerability occurs when the Broken Link Checker plugin fails to properly sanitize user input before rendering it in the admin panel's HTML output. Attackers can craft malicious URLs or link text that, when processed by the plugin, gets embedded directly into the admin interface without proper HTML escaping or encoding. This creates an environment where JavaScript code can be injected and executed within the context of the admin user's browser session, potentially allowing attackers to escalate privileges, steal session cookies, or perform unauthorized actions on behalf of the administrator. The vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications, and represents a classic example of insufficient input sanitization leading to code execution in the victim's browser context.
The operational impact of CVE-2015-5057 extends beyond simple script execution, as it provides attackers with a potential pathway to full administrative compromise of WordPress installations. When an authenticated administrator visits the admin panel page where the malicious content is displayed, the injected scripts execute with the privileges of that user, potentially enabling attackers to modify site content, install malware, modify user accounts, or extract sensitive data. The vulnerability is particularly dangerous because it operates within the trusted admin environment, making it difficult for standard security measures to detect the malicious activity. This aligns with ATT&CK technique T1059.007 for scripting and T1548.001 for abuse of privileges, as attackers can leverage the compromised admin session to maintain persistence and expand their access within the WordPress environment.
Mitigation strategies for CVE-2015-5057 focus primarily on immediate plugin updates to version 1.10.9 or later, which contain the necessary input sanitization fixes. Organizations should also implement additional defensive measures including regular security audits of installed plugins, monitoring for suspicious activity in admin panels, and implementing content security policies to limit script execution capabilities. Network-level protections such as web application firewalls can provide additional layers of defense, though the most effective approach remains maintaining current plugin versions and following secure coding practices. The vulnerability underscores the importance of keeping all WordPress components updated and demonstrates how third-party plugins can create significant security risks when not properly maintained. Security teams should also consider implementing automated vulnerability scanning tools that can detect outdated plugins and alert administrators to potential XSS vulnerabilities in their WordPress installations, as this type of flaw can be particularly challenging to identify without specialized scanning tools due to its context-dependent nature within the admin interface.