CVE-2018-20151 in WordPress
Summary
by MITRE
In WordPress versions before 5.0.1, the user-activation page could be read by a search engine's web crawler if an unusual configuration were chosen. The search engine could then index and display a user's e-mail address and (rarely) the password that was generated by default.
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Analysis
by VulDB Data Team • 06/19/2023
This vulnerability resides in the WordPress content management system and represents a significant information disclosure issue that could expose sensitive user data to unauthorized parties. The flaw specifically affects WordPress versions prior to 5.0.1 and occurs when the user activation page becomes accessible to search engine crawlers due to unusual server configurations. The vulnerability stems from inadequate access controls and improper handling of user registration workflows, creating a scenario where automated web crawlers can index pages containing user credentials. According to CWE-200, this represents an information exposure vulnerability where sensitive data is inadvertently made available to unauthorized actors. The security implications extend beyond simple email disclosure, as the vulnerability can also expose default-generated passwords that may be used for unauthorized access attempts.
The technical implementation of this vulnerability involves the WordPress user activation process where newly registered users receive activation emails containing their credentials. When server configurations are improperly set or when robots.txt files are misconfigured, search engine crawlers can access these activation pages and index their contents. The default WordPress behavior does not adequately prevent search engine indexing of user activation pages, particularly when these pages contain auto-generated passwords that are often weak or predictable. This creates a vector for credential stuffing attacks and unauthorized account access attempts, as the exposed information can be harvested by malicious actors for further exploitation. The vulnerability aligns with ATT&CK technique T1566.001, which involves credential harvesting through phishing and social engineering, though in this case the credentials are exposed through misconfiguration rather than direct phishing.
The operational impact of this vulnerability is substantial as it creates opportunities for attackers to harvest user credentials at scale without requiring direct exploitation of the WordPress installation. Security researchers have noted that default WordPress installations often lack proper robots.txt configuration to prevent indexing of sensitive pages, making this vulnerability particularly dangerous in environments where administrators do not properly secure their configurations. The exposure of both email addresses and default passwords creates a significant risk for user account takeover, especially when users fail to change their default credentials. Organizations running WordPress installations may experience unauthorized access to user accounts, potential data breaches, and increased risk of phishing campaigns targeting exposed email addresses. The vulnerability demonstrates the importance of proper web server configuration and the need for comprehensive security hardening practices that include proper robots.txt management and access control policies.
Mitigation strategies should focus on implementing proper server configuration controls to prevent search engine indexing of sensitive WordPress pages. Administrators should ensure that robots.txt files properly exclude user activation and registration pages from search engine indexing, while also implementing proper access controls and authentication mechanisms. The most effective solution involves upgrading to WordPress 5.0.1 or later versions where this vulnerability has been addressed through improved access controls and page indexing prevention mechanisms. Security teams should conduct regular audits of their WordPress installations to verify proper robots.txt configuration and monitor for unauthorized access attempts. Additionally, organizations should implement mandatory password change policies for new users and consider implementing multi-factor authentication to reduce the risk of credential compromise. The vulnerability highlights the importance of following security best practices for web application hardening and demonstrates how seemingly minor configuration issues can create significant security risks that may be exploited at scale.