CVE-2022-4580 in Twenty20 Image Before-After Plugin
Summary
by MITRE • 02/13/2023
The Twenty20 Image Before-After WordPress plugin through 1.5.9 does not validate and escape some of its shortcode attributes before outputting them back in a page/post where the shortcode is embed, which could allow users with the contributor role and above to perform Stored Cross-Site Scripting attacks
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Analysis
by VulDB Data Team • 03/12/2023
The Twenty20 Image Before-After WordPress plugin version 1.5.9 contains a critical stored cross-site scripting vulnerability that affects WordPress installations where the plugin is active. This vulnerability stems from insufficient validation and sanitization of shortcode attributes within the plugin's code implementation. The flaw specifically targets the plugin's handling of user-provided input through shortcode parameters, creating an avenue for malicious actors to inject persistent malicious scripts into WordPress pages and posts. The vulnerability is particularly concerning because it allows users with the contributor role and above to exploit this weakness, significantly expanding the potential attack surface beyond just administrators. The affected shortcode attributes are processed without proper escaping mechanisms, meaning that any malicious script content entered by an attacker can be stored within the WordPress database and subsequently executed whenever the affected page is loaded by other users. This stored nature of the vulnerability means that the malicious payload persists even after the initial injection, making it particularly dangerous for websites with multiple contributors or users who can submit content through the WordPress interface.
The technical implementation of this vulnerability can be analyzed through the lens of CWE-79 which specifically addresses cross-site scripting flaws in web applications. The plugin fails to properly sanitize user input before rendering it within HTML contexts, creating an environment where attacker-controlled data can be interpreted as executable code. The vulnerability operates at the application layer and specifically affects the plugin's shortcode processing functionality, which is a common entry point for malicious actors in WordPress environments. The fact that contributors and above can exploit this vulnerability indicates that the plugin does not properly implement role-based access controls for input validation, allowing less privileged users to perform actions that should typically be restricted to administrators. This misconfiguration creates a privilege escalation vector that can be leveraged to gain unauthorized access to user sessions or execute arbitrary commands within the context of the victim's browser. The stored nature of the XSS attack means that the malicious code is permanently embedded in the website's content, making it extremely difficult to detect and remove without proper database cleanup procedures.
The operational impact of this vulnerability extends beyond simple script execution and can lead to significant security breaches within affected WordPress installations. Attackers can leverage this stored XSS vulnerability to hijack user sessions, steal sensitive information, perform unauthorized actions on behalf of logged-in users, or redirect victims to malicious websites. The vulnerability affects not only the plugin's immediate functionality but also poses risks to the entire WordPress ecosystem, as compromised users can potentially access other parts of the website or even the underlying server infrastructure. The attack surface is particularly wide because the vulnerability affects any page or post where the Twenty20 plugin shortcode is embedded, meaning that even content published by trusted contributors could become a vector for malicious activity. The persistent nature of stored XSS makes this vulnerability particularly dangerous for websites with high user interaction or content management, as the malicious payload can affect multiple users over extended periods. This vulnerability also impacts the website's integrity and can be used to manipulate content, deface pages, or spread malware to visitors who access the compromised pages.
Mitigation strategies for this vulnerability should focus on immediate remediation and long-term security hardening measures. The most effective immediate solution is to update the Twenty20 Image Before-After plugin to version 1.5.10 or later, which contains the necessary patches to address the XSS vulnerability. Organizations should also implement comprehensive input validation and output escaping mechanisms for all user-provided data within their WordPress installations, particularly for shortcode attributes and other dynamic content rendering features. The implementation of Content Security Policy headers can provide additional protection against XSS attacks by restricting the sources from which scripts can be loaded. Security monitoring should be enhanced to detect unusual shortcode usage patterns or unexpected content modifications that might indicate exploitation attempts. Regular security audits and vulnerability assessments should be conducted to identify similar issues in other plugins or themes that may be vulnerable to similar input validation flaws. Organizations should also consider implementing role-based access controls that limit the ability of lower-privilege users to modify content in ways that could introduce security vulnerabilities. The ATT&CK framework's T1548.002 technique for privilege escalation through web shells and T1203 for exploitation of software vulnerabilities should be considered when developing incident response procedures for this type of vulnerability. Additionally, maintaining up-to-date security patches for WordPress core and all plugins ensures that known vulnerabilities are addressed promptly, reducing the window of opportunity for attackers to exploit these issues.