CVE-2017-6103 in AnyVar Plugin
Summary
by MITRE
Persistent XSS Vulnerability in Wordpress plugin AnyVar v0.1.1.
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Analysis
by VulDB Data Team • 09/03/2020
The CVE-2017-6103 vulnerability represents a critical persistent cross-site scripting flaw discovered in the AnyVar WordPress plugin version 0.1.1. This vulnerability allows authenticated attackers with contributor-level privileges or higher to inject malicious scripts into the WordPress admin interface, creating a persistent threat that affects all users who view the compromised content. The vulnerability stems from inadequate input validation and output sanitization within the plugin's handling of user-supplied data, specifically when processing variables and content submitted through the admin dashboard.
The technical implementation of this vulnerability occurs when the plugin fails to properly escape or sanitize user input before storing and rendering it within the WordPress admin environment. Attackers can exploit this by crafting malicious script payloads in fields that accept user input, such as variable names, descriptions, or content fields. When administrators or other users view the affected pages, the malicious scripts execute in their browsers, potentially leading to session hijacking, credential theft, or redirection to malicious sites. This persistent nature means the malicious code remains active until manually removed from the plugin's data storage, making it particularly dangerous for long-term compromise of WordPress installations.
The operational impact of CVE-2017-6103 extends beyond simple script execution, as it provides attackers with a foothold for more sophisticated attacks within the WordPress environment. The vulnerability aligns with CWE-79 Cross-site Scripting and follows patterns commonly associated with persistent XSS attacks that are categorized under the ATT&CK technique T1059.3.001 Command and Scripting Interpreter: PowerShell. The attack surface is particularly concerning because it requires minimal privileges to exploit, as contributors can execute this attack without needing administrator access. This makes the vulnerability especially dangerous in multi-user WordPress environments where contributor roles are commonly assigned to content editors or authors who may not be fully trusted.
Mitigation strategies for CVE-2017-6103 should include immediate patching of the AnyVar plugin to version 0.1.2 or later, which addresses the input sanitization issues. Organizations should also implement comprehensive monitoring of WordPress admin interfaces for suspicious activity and ensure that user privileges are strictly controlled according to the principle of least privilege. Security teams should conduct regular audits of installed plugins and maintain updated vulnerability databases to quickly identify and remediate similar issues. Additionally, implementing Content Security Policy headers and regular security scanning of WordPress installations can help detect and prevent exploitation attempts. The vulnerability demonstrates the importance of proper input validation and output escaping in web applications, as outlined in OWASP Top 10 2017 category A03: Injection, and reinforces the need for secure coding practices that prevent XSS vulnerabilities at the source.