CVE-2017-18603 in postman-smtp Plugin
Summary
by MITRE
The postman-smtp plugin through 2017-10-04 for WordPress has XSS via the wp-admin/tools.php?page=postman_email_log page parameter.
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Analysis
by VulDB Data Team • 12/19/2023
The postman-smtp plugin for WordPress represents a critical security vulnerability through its implementation of cross-site scripting (XSS) in the administrative interface. This vulnerability specifically affects versions of the plugin released through October 4, 2017, and manifests within the wp-admin/tools.php?page=postman_email_log page parameter. The flaw demonstrates a classic input validation failure where user-supplied data is not properly sanitized before being rendered in the web interface, creating an exploitable condition that allows malicious actors to inject arbitrary JavaScript code into the administrative context.
The technical implementation of this vulnerability stems from insufficient output escaping and input validation mechanisms within the plugin's administrative dashboard. When administrators navigate to the email log page, the page parameter value is directly incorporated into the HTML output without proper sanitization or encoding, enabling attackers to craft malicious payloads that execute within the context of the administrator's browser session. This represents a CWE-79 vulnerability classification, specifically a cross-site scripting flaw in a web application, where the application fails to validate or escape user-provided data before including it in dynamically generated web pages. The attack vector operates through the standard HTTP GET parameter mechanism, where an attacker can construct a malicious URL containing JavaScript code within the page parameter that executes when the administrator loads the page.
The operational impact of this vulnerability extends beyond simple data theft or defacement, as it provides attackers with elevated privileges within the WordPress administrative environment. An attacker who successfully exploits this vulnerability can execute arbitrary JavaScript code with the privileges of the authenticated administrator, potentially leading to complete system compromise. This includes the ability to modify or delete content, install malicious plugins, access sensitive user data, and establish persistent backdoors. The vulnerability aligns with ATT&CK technique T1059.007 for Command and Scripting Interpreter: JavaScript, as it leverages JavaScript execution within the browser context to achieve unauthorized access. Additionally, this flaw contributes to broader attack chains that may include credential theft through session hijacking or privilege escalation to gain access to other systems within the network perimeter.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security posture improvements. The most effective immediate solution involves updating the postman-smtp plugin to version 2017-10-05 or later, where the XSS vulnerability has been patched through proper input validation and output escaping mechanisms. Organizations should implement comprehensive patch management procedures to ensure all WordPress plugins and themes remain current with security updates. Additional protective measures include implementing Content Security Policy headers to limit script execution, conducting regular security audits of installed plugins, and establishing web application firewall rules to detect and block suspicious parameter values. The vulnerability also highlights the importance of principle of least privilege, where administrators should limit their exposure by using accounts with minimal required permissions and implementing multi-factor authentication to reduce the impact of successful exploitation attempts.