Executive Summary

The vulnerability exists in the Cryptocurrency Prijsvergelijking Widget plugin for WordPress, version 1.0. It is a Stored Cross-Site Scripting (XSS) issue caused by insufficient output escaping in the as_get_coin_shortcode() function.

Specifically, the 'width' and 'height' shortcode attributes are rendered directly into the style attribute of an iframe element without proper escaping, such as using esc_attr().

An attacker with contributor-level access or higher can inject malicious scripts by providing specially crafted values that prematurely terminate the style attribute and inject arbitrary HTML attributes, leading to script execution when users access the affected page.

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Impact Analysis

This vulnerability allows authenticated attackers with contributor-level access or above to inject arbitrary web scripts into pages.

When other users access these pages, the injected scripts execute in their browsers, potentially leading to theft of sensitive information, session hijacking, or other malicious actions.

Because the attack requires contributor-level access, it may be limited to insiders or users with some level of trust, but it still poses a significant risk to site integrity and user security.

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Detection Guidance

This vulnerability involves Stored Cross-Site Scripting (XSS) in the Cryptocurrency Prijsvergelijking Widget plugin for WordPress, specifically in the as_get_coin_shortcode() function where the 'width' and 'height' shortcode attributes are not properly escaped.

To detect this vulnerability on your system, you can search for instances where the plugin is used and check for injected or malformed iframe style attributes containing suspicious payloads such as "100px;"onload="alert(1)" or similar patterns.

Since this is a WordPress plugin vulnerability, you can also scan your WordPress installation for the presence of version 1.0 of the Cryptocurrency Prijsvergelijking Widget plugin.

• Use WP-CLI to check the installed plugin version: wp plugin list --status=active
• Search your WordPress database for suspicious iframe style attributes using SQL queries, for example: SELECT * FROM wp_posts WHERE post_content LIKE '%iframe%style%onload=%';
• Use network monitoring tools or web application scanners to detect XSS payloads in HTTP responses containing the vulnerable iframe.

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Compliance Impact

The vulnerability allows authenticated attackers with contributor-level access and above to inject arbitrary web scripts that execute when users access the injected pages. This can lead to unauthorized access or manipulation of user data.

Such unauthorized script execution could potentially result in data breaches or exposure of personal information, which may impact compliance with data protection regulations like GDPR and HIPAA that require safeguarding user data and preventing unauthorized access.

However, the provided context does not explicitly state the direct effects on compliance with these standards.

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Mitigation Strategies

Immediate mitigation steps include updating or removing the vulnerable Cryptocurrency Prijsvergelijking Widget plugin if an update is available that fixes the issue.

If no update is available, restrict contributor-level and higher user access to trusted users only, as the vulnerability requires authenticated users with contributor-level access or above to exploit.

Implement Web Application Firewall (WAF) rules to block suspicious payloads attempting to inject scripts via the iframe style attribute.

Review and sanitize any user-generated content that uses the shortcode attributes 'width' and 'height' to prevent injection of malicious code.

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