CVE-2022-4100 in WP Cerber Security Plugin
Summary
by MITRE • 08/31/2024
The WP Cerber Security plugin for WordPress is vulnerable to IP Protection bypass in versions up to, and including 9.4 due to the plugin improperly checking for a visitor's IP address. This makes it possible for an attacker whose IP address has been blocked to bypass this control by setting the X-Forwarded-For: HTTP header to an IP Address that hasn't been blocked.
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Analysis
by VulDB Data Team • 09/04/2024
The WP Cerber Security plugin represents a widely deployed security solution for wordpress environments designed to protect against various cyber threats including brute force attacks and malicious IP tracking. This particular vulnerability affects versions up to and including 9.4 where the plugin fails to properly validate visitor IP addresses through a critical flaw in its access control mechanism. The vulnerability stems from the plugin's improper handling of HTTP headers, specifically the X-Forwarded-For header which is commonly used in web applications to identify the original IP address of a client connecting through a proxy or load balancer. When an attacker's IP address is blocked by the plugin's security measures, they can circumvent this restriction by manipulating the X-Forwarded-For HTTP header to include an IP address that has not been blacklisted, thereby gaining unauthorized access to the protected wordpress site.
The technical nature of this vulnerability aligns with CWE-284 Access Control Bypass, which describes weaknesses where a system fails to properly enforce access restrictions, allowing unauthorized users to bypass security controls. This flaw operates at the application layer of the network stack and represents a classic case of insufficient input validation where the plugin trusts HTTP headers without proper verification of their authenticity. The vulnerability exploits the trust model inherent in web application security where certain headers like X-Forwarded-For are assumed to contain legitimate client information, but in this case the plugin fails to validate that these headers originate from legitimate sources or are properly formatted. Attackers can leverage this bypass to circumvent rate limiting, brute force protection, and IP blocking mechanisms that are fundamental to protecting wordpress installations from automated attacks and unauthorized access attempts.
From an operational impact perspective, this vulnerability compromises the core security posture of wordpress sites relying on WP Cerber Security plugin for protection against malicious actors. The bypass allows attackers to repeatedly attempt login credentials or exploit other security controls without being properly rate limited or blocked by the plugin's IP management features. This creates a significant risk for wordpress installations where brute force attacks are common, as attackers can effectively circumvent the very protections designed to prevent such attacks. The vulnerability essentially renders the IP blocking functionality ineffective, undermining the security controls that administrators rely on to protect their sites from automated scanning and attack vectors. Organizations using this plugin may experience unauthorized access to their wordpress admin panels, leading to potential data breaches, site defacement, or malicious code injection through compromised administrative access.
The exploitation of this vulnerability follows patterns consistent with ATT&CK technique T1110 Brute Force, where adversaries attempt to gain access to systems through repeated login attempts. However, the bypass capability means that attackers can perform these attempts without the normal rate limiting or IP blocking controls that would typically prevent such activities. Security professionals should consider this vulnerability when assessing their wordpress security posture and implementing defense-in-depth strategies. Mitigation strategies include immediate upgrading to patched versions of the WP Cerber Security plugin, implementing additional network-level controls such as firewall rules to restrict access to the wordpress admin interface, and monitoring for unusual access patterns that might indicate exploitation attempts. Organizations should also consider implementing multiple layers of authentication controls including two-factor authentication and IP whitelisting for administrative access to reduce the risk associated with such bypass vulnerabilities. The vulnerability demonstrates the importance of proper header validation and the potential consequences of relying on HTTP headers without proper verification mechanisms in security-critical applications.