CVE-2018-18461 in Arigato Autoresponder
Summary
by MITRE
The Arigato Autoresponder and Newsletter (aka bft-autoresponder) v2.5.1.7 plugin for WordPress allows remote attackers to execute arbitrary code via PHP code in attachments[] data to models/attachment.php.
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Analysis
by VulDB Data Team • 04/05/2020
The CVE-2018-18461 vulnerability resides within the Arigato Autoresponder and Newsletter WordPress plugin version 2.5.1.7, representing a critical remote code execution flaw that enables attackers to inject and execute arbitrary PHP code through maliciously crafted attachments. This vulnerability specifically targets the models/attachment.php file, which processes user-supplied data without adequate input validation or sanitization mechanisms. The flaw demonstrates a classic improper input validation issue that falls under CWE-20, where the application fails to properly validate or sanitize user-provided data before processing it, creating an avenue for malicious code injection.
The technical exploitation of this vulnerability occurs when an attacker submits specially crafted PHP code within the attachments[] parameter to the models/attachment.php endpoint. This parameter is likely used to handle file attachments or media uploads within the plugin's functionality. The vulnerability stems from the plugin's failure to implement proper sanitization or validation of the attachment data, allowing malicious payloads to be executed within the context of the WordPress application. This represents a severe security oversight that directly violates the principle of least privilege and input validation, as the plugin processes user-supplied data without proper security controls. The vulnerability can be classified under ATT&CK technique T1059.007 for PHP and the broader category of command and control communications.
The operational impact of this vulnerability extends far beyond simple code execution, as it provides attackers with complete control over the affected WordPress installation. Successful exploitation allows adversaries to upload malicious files, execute arbitrary commands, access sensitive data, modify website content, and potentially establish persistent backdoors. The vulnerability affects any WordPress site running the vulnerable plugin version, making it particularly dangerous as it targets a widely used email marketing solution. Attackers can leverage this flaw to compromise entire websites, steal user credentials, deface content, or use the compromised site as a launchpad for further attacks against other systems. The implications are particularly severe given that WordPress plugins often operate with elevated privileges and have access to sensitive system resources.
Mitigation strategies for CVE-2018-18461 require immediate action from affected organizations, beginning with the mandatory upgrade to the patched version of the Arigato Autoresponder and Newsletter plugin. System administrators should also implement network-level protections such as web application firewalls that can detect and block malicious attachment parameter submissions. Additional defensive measures include restricting file upload capabilities, implementing proper input validation at multiple layers, and monitoring for suspicious activity related to attachment processing. Organizations should conduct comprehensive security assessments of their WordPress installations to identify any other vulnerable plugins or themes that may present similar risks. The vulnerability underscores the importance of regular security updates, proper input validation practices, and maintaining an inventory of all installed WordPress plugins to ensure timely patch management. Security teams should also consider implementing automated vulnerability scanning tools that can detect such flaws in their web applications.