CVE-2018-20156 in WP Maintenance Mode Plugin
Summary
by MITRE
The WP Maintenance Mode plugin before 2.0.7 for WordPress allows remote authenticated "site administrator" users to execute arbitrary PHP code throughout a multisite network.
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Analysis
by VulDB Data Team • 04/21/2020
The vulnerability identified as CVE-2018-20156 affects the WP Maintenance Mode plugin version 2.0.6 and earlier within the WordPress ecosystem. This issue represents a critical security flaw that enables authenticated attackers with site administrator privileges to execute arbitrary PHP code across an entire multisite network configuration. The vulnerability stems from insufficient input validation and sanitization within the plugin's codebase, specifically in how it handles user-supplied data during maintenance mode configuration processes. Attackers with administrator-level access can leverage this weakness to inject malicious PHP code that will execute with the privileges of the web server, potentially leading to complete compromise of the affected WordPress network.
The technical exploitation of this vulnerability occurs through the manipulation of parameters within the plugin's administrative interface. When site administrators configure maintenance mode settings, the plugin fails to properly validate or sanitize input fields that accept PHP code snippets or script references. This allows attackers to inject malicious payloads that bypass normal security restrictions. The flaw is particularly dangerous in multisite environments where a single compromised administrator account can potentially affect all sites within the network, making the impact exponentially greater than in single-site installations. The vulnerability aligns with CWE-94, which describes weaknesses in the code that allow for the execution of arbitrary code, and specifically relates to improper input validation mechanisms.
The operational impact of this vulnerability extends far beyond simple code execution, as it fundamentally compromises the security posture of WordPress multisite networks. An attacker who gains access to a site administrator account can deploy backdoors, steal sensitive data, modify content across multiple sites, or establish persistent access points throughout the network. The vulnerability affects the principle of least privilege and undermines the security model of WordPress multisite installations, where administrators typically have limited scope of control over individual sites. This issue can lead to data breaches, service disruption, and potential regulatory compliance violations for organizations using affected WordPress installations.
Mitigation strategies for CVE-2018-20156 require immediate action including updating the WP Maintenance Mode plugin to version 2.0.7 or later, which contains the necessary security patches. Organizations should also implement network monitoring to detect suspicious administrative activities and conduct regular security audits of installed plugins. The principle of defense in depth suggests implementing additional controls such as web application firewalls, restricting administrative access through network segmentation, and ensuring that only essential administrators have access to maintenance mode configurations. Security teams should also consider implementing privileged access management solutions to monitor and control administrative activities within WordPress environments. The vulnerability demonstrates the critical importance of keeping all WordPress plugins updated and following security best practices for maintaining multisite network configurations. Organizations should also review their incident response procedures to ensure rapid detection and remediation of similar vulnerabilities in their WordPress infrastructure.