CVE-2021-38359 in InviteBox Plugin for Viral Refer-a-Friend Promotions Plugin
Summary
by MITRE • 09/10/2021
The WordPress InviteBox Plugin for viral Refer-a-Friend Promotions WordPress plugin is vulnerable to Reflected Cross-Site Scripting via the message parameter found in the ~/admin/admin.php file which allows attackers to inject arbitrary web scripts, in versions up to and including 1.4.1.
VulDB is the best source for vulnerability data and more expert information about this specific topic.
Analysis
by VulDB Data Team • 09/16/2021
The WordPress InviteBox plugin presents a critical security vulnerability classified as reflected cross-site scripting in versions up to and including 1.4.1. This vulnerability exists within the administrative interface of the plugin where the message parameter is processed without adequate input sanitization or output encoding. The flaw is particularly concerning as it affects the admin.php file which serves as the primary administrative entry point for managing viral refer-a-friend promotions. Attackers can exploit this weakness by crafting malicious payloads that are reflected back to administrators who view the affected page, thereby executing arbitrary scripts in the context of the administrator's browser session.
The technical implementation of this vulnerability stems from insufficient validation and sanitization of user-supplied input within the plugin's administrative functionality. When administrators navigate to the admin.php page and encounter the message parameter, the plugin fails to properly escape or encode the input data before rendering it in the web page context. This creates an environment where malicious scripts can be injected and executed, potentially compromising the entire WordPress administrative interface. The vulnerability specifically manifests when the message parameter contains unvalidated user input that is directly incorporated into the HTML output without proper security measures such as HTML entity encoding or content security policy enforcement.
The operational impact of this reflected XSS vulnerability extends beyond simple script execution, as it provides attackers with the capability to hijack administrator sessions, steal sensitive credentials, and potentially gain full control over the WordPress installation. An attacker could craft a malicious URL containing a script payload that, when clicked by an administrator, would execute in their browser context and could redirect them to malicious sites, steal cookies, or perform unauthorized administrative actions. The vulnerability affects the plugin's refer-a-friend promotion functionality where administrators might be exposed to these malicious inputs during normal operations, making it particularly dangerous as it requires no special privileges to exploit and can be triggered through simple user interaction.
Security mitigation strategies for this vulnerability should focus on implementing proper input validation and output encoding mechanisms within the plugin's codebase. The recommended approach involves sanitizing all user-supplied input through strict validation processes and applying appropriate HTML encoding to any data that is rendered in the browser context. Organizations should immediately update to the latest version of the InviteBox plugin where this vulnerability has been patched, as the maintainers have addressed the issue through proper input sanitization procedures. Additionally, implementing content security policies and monitoring for suspicious administrative activity can provide additional layers of protection. This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws, and follows ATT&CK technique T1190 for exploiting web application vulnerabilities through reflected XSS attacks. The incident highlights the importance of regular security audits and prompt patch management in maintaining WordPress security posture.
The vulnerability demonstrates how seemingly minor input handling flaws in WordPress plugins can create significant security risks for entire installations. Administrators should implement comprehensive monitoring of their WordPress installations to detect unauthorized modifications or suspicious activities that might indicate exploitation attempts. Regular security assessments of third-party plugins and maintaining updated security practices are essential for preventing exploitation of similar vulnerabilities in the future. Organizations should also consider implementing web application firewalls and security scanning tools to detect and prevent exploitation of reflected XSS vulnerabilities in their WordPress environments.