CVE-2023-45759 in Peters Custom Anti-Spam Plugin
Summary
by MITRE • 10/25/2023
Unauth. Reflected Cross-Site Scripting (XSS) vulnerability in Peter Keung Peter’s Custom Anti-Spam plugin
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Analysis
by VulDB Data Team • 11/16/2023
The CVE-2023-45759 vulnerability represents a critical unauthenticated reflected cross-site scripting flaw discovered in the Peter Keung Peter's Custom Anti-Spam WordPress plugin. This vulnerability resides within the plugin's handling of user input parameters, specifically in how it processes and reflects data back to users without proper sanitization or output encoding. The issue allows attackers to inject malicious scripts into web pages viewed by other users, potentially compromising their sessions and enabling unauthorized actions. The vulnerability affects the plugin's administrative interfaces and frontend components where user-supplied data is directly incorporated into HTML responses without adequate validation or escaping mechanisms. According to CWE-79, this falls under the category of Cross-Site Scripting, which is one of the most prevalent and dangerous web application security flaws identified by the CWE project. The vulnerability's impact is amplified by the fact that it requires no authentication to exploit, making it particularly dangerous as any visitor to a compromised website could become a victim of the attack.
The technical exploitation of this reflected XSS vulnerability occurs when an attacker crafts a malicious URL containing script code within parameters that are processed by the vulnerable plugin. When an unsuspecting user visits this crafted URL, the malicious script executes in their browser context within the legitimate website's domain. This enables attackers to perform actions such as stealing session cookies, redirecting users to malicious sites, defacing web pages, or executing arbitrary code within the user's browser. The vulnerability's operational impact extends beyond simple data theft as it can serve as a stepping stone for more sophisticated attacks, including privilege escalation within the compromised WordPress environment or the installation of backdoors. The ATT&CK framework categorizes this vulnerability under T1190 - Exploit Public-Facing Application, where attackers leverage web application flaws to gain initial access to target systems. The reflected nature of the vulnerability means that the malicious payload is not stored on the server but is instead reflected back to the user through the web application's response, making it harder to detect through traditional server-side logging mechanisms.
The security implications of CVE-2023-45759 extend to the broader WordPress ecosystem, as compromised websites become potential entry points for attackers seeking to establish persistent access to larger networks. WordPress plugins represent a significant attack surface, and vulnerabilities in popular plugins like the Custom Anti-Spam plugin can affect thousands of websites simultaneously. The vulnerability demonstrates a fundamental failure in input validation and output encoding practices that should be implemented at every layer of web application development. Organizations using this plugin are exposed to risks including credential theft, unauthorized content modification, and potential data exfiltration. The lack of authentication requirements for exploitation makes this vulnerability particularly concerning for high-traffic websites where user interaction is frequent and unpredictable. Security professionals should consider this vulnerability as part of a broader threat landscape where attackers increasingly target content management systems through plugin vulnerabilities rather than core application flaws. The vulnerability also highlights the importance of regular security audits and patch management processes, as reflected XSS issues often remain undetected for extended periods until actively exploited in the wild.
Mitigation strategies for CVE-2023-45759 should focus on immediate remediation through plugin updates from the vendor, which is the primary recommended approach. System administrators should also implement additional protective measures such as web application firewalls that can detect and block malicious script payloads, proper input validation at all entry points, and comprehensive output encoding to prevent script execution in HTML contexts. The implementation of Content Security Policies can provide additional defense-in-depth layers by restricting the sources from which scripts can be executed within the website's context. Organizations should conduct thorough vulnerability assessments of their WordPress installations to identify other potentially vulnerable plugins and themes. Regular security monitoring and user education about phishing attempts that may leverage such vulnerabilities are also essential components of a comprehensive security strategy. The vulnerability serves as a reminder of the critical importance of maintaining up-to-date software components and implementing robust security practices throughout the web application development lifecycle. According to industry best practices, all web applications should implement proper input sanitization, output encoding, and security headers to prevent such vulnerabilities from being exploited in production environments.