CVE-2015-9273 in wp-slimstat Plugin
Summary
by MITRE
The wp-slimstat (aka Slimstat Analytics) plugin before 4.1.6.1 for WordPress has XSS via an HTTP Referer header, or via a field associated with JavaScript-based Referer tracking.
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Analysis
by VulDB Data Team • 05/23/2023
The wp-slimstat plugin for WordPress contains a cross-site scripting vulnerability that affects versions prior to 4.1.6.1, representing a critical security flaw in web application input validation. This vulnerability stems from insufficient sanitization of user-supplied data within the plugin's handling of HTTP Referer headers and JavaScript-based referer tracking fields. The flaw allows attackers to inject malicious scripts into the plugin's output, potentially compromising user sessions and enabling unauthorized access to sensitive data. The vulnerability is categorized under CWE-79 as a cross-site scripting weakness, which occurs when web applications fail to properly validate or escape user input before rendering it in web pages.
The technical exploitation of this vulnerability occurs when the plugin processes HTTP Referer headers without adequate input filtering or output encoding. Attackers can craft malicious Referer values containing script tags or other malicious payloads that get executed in the context of legitimate users' browsers. The vulnerability extends to fields associated with JavaScript-based referer tracking, indicating that the plugin's sanitization mechanisms are insufficient across multiple input vectors. This represents a classic server-side XSS attack vector where the malicious input is processed and stored within the application's data structures before being served back to users, making it particularly dangerous as it can affect multiple users who view the affected pages.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable session hijacking, credential theft, and data manipulation within the WordPress environment. An attacker who successfully exploits this vulnerability can potentially escalate privileges, access sensitive user information, or even take complete control of affected WordPress installations. The attack surface is broad since HTTP Referer headers are commonly used for analytics and tracking purposes, making the vulnerability particularly prevalent across various WordPress deployments. This vulnerability aligns with ATT&CK technique T1566.001 for initial access through spearphishing attachments and T1071.004 for application layer protocol usage, demonstrating how seemingly benign tracking functionality can become a security vector.
Mitigation strategies for this vulnerability require immediate patching to version 4.1.6.1 or later, which includes proper input sanitization and output encoding mechanisms. Administrators should implement comprehensive input validation at multiple layers including web application firewalls, content security policies, and regular security audits of installed plugins. The fix typically involves implementing proper HTML entity encoding for all user-supplied data before rendering it in web pages, along with strict validation of referer header formats. Security monitoring should include detection of unusual referer header patterns and implementation of CSP headers to prevent script execution. Organizations should also consider implementing automated patch management systems to ensure timely updates of all WordPress plugins and core components, as this vulnerability demonstrates the importance of maintaining up-to-date security measures in content management systems.