CVE-2021-4425 in Defender Security Plugin
Summary
by MITRE • 07/12/2023
The Defender Security plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 2.4.6. This is due to missing or incorrect nonce validation on the verify_otp_login_time() function. This makes it possible for unauthenticated attackers to verify a one time login via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
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Analysis
by VulDB Data Team • 07/30/2023
The CVE-2021-4425 vulnerability affects the Defender Security plugin for WordPress, specifically targeting versions up to and including 2.4.6. This represents a critical cross-site request forgery weakness that undermines the security posture of WordPress installations relying on this plugin for two-factor authentication. The vulnerability stems from inadequate nonce validation mechanisms within the plugin's authentication flow, creating a pathway for malicious actors to exploit the system's trust model. The issue directly impacts the plugin's ability to maintain secure one-time login verification processes, potentially allowing unauthorized access to administrative accounts.
The technical flaw manifests in the verify_otp_login_time() function where nonce validation is either completely absent or improperly implemented, failing to validate the authenticity of requests originating from legitimate administrators. This vulnerability operates under the principle that an attacker can craft a malicious request that, when executed by an authenticated administrator, would bypass the normal one-time password verification process. The nonce mechanism serves as a cryptographic token that ensures requests originate from legitimate sources and have not been tampered with during transmission, yet this protection has been compromised in the affected versions.
The operational impact of this vulnerability extends beyond simple privilege escalation, as it enables attackers to potentially gain full administrative control over WordPress sites without requiring legitimate credentials. The attack vector relies on social engineering tactics where administrators are tricked into clicking malicious links or visiting compromised websites that trigger the forged requests. This creates a dangerous scenario where even well-protected accounts become vulnerable due to the trust relationship between the browser and the targeted website. The vulnerability affects the core authentication mechanism of the plugin, undermining the entire two-factor authentication system's integrity and rendering it ineffective against this specific attack pattern.
Organizations using the Defender Security plugin must implement immediate mitigation strategies to address this vulnerability. The primary recommendation involves updating to the latest plugin version where the nonce validation has been properly implemented and tested. Security administrators should also consider implementing additional monitoring for suspicious authentication patterns and reviewing access logs for potential exploitation attempts. The vulnerability aligns with CWE-352, which specifically addresses cross-site request forgery weaknesses in web applications, and maps to ATT&CK technique T1566.001 for initial access through spearphishing attachments or links. Organizations should also consider implementing Content Security Policy headers and additional authentication controls to reduce the attack surface and mitigate potential exploitation attempts.