CVE-2009-3540 in Ultra Classifieds Pro
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in listads.php in YourFreeWorld Ultra Classifieds Pro allows remote attackers to inject arbitrary web script or HTML via the cn parameter. NOTE: the provenance of this information is unknown; the details are obtained solely from third party information.
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Analysis
by VulDB Data Team • 12/27/2017
This cross-site scripting vulnerability exists in the YourFreeWorld Ultra Classifieds Pro application's listads.php script where the cn parameter fails to properly sanitize user input before incorporating it into dynamically generated web content. The flaw represents a classic reflected XSS vulnerability where malicious input submitted through the cn parameter is immediately returned to users without adequate output encoding or validation mechanisms. This vulnerability falls under CWE-79 which specifically addresses improper neutralization of input during web page generation, making it a direct descendant of the fundamental web application security principle that all user-supplied data must be treated as untrusted and properly validated before inclusion in web responses.
The operational impact of this vulnerability is significant as it allows remote attackers to execute arbitrary web scripts or HTML content within the context of authenticated user sessions. An attacker could craft malicious URLs containing script payloads in the cn parameter that would execute when victims click on the links or when the page is rendered in their browsers. This creates potential for session hijacking, credential theft, defacement of the classifieds platform, and redirection to malicious sites. The vulnerability is particularly dangerous because it operates without requiring any authentication or privileged access, making it a prime target for mass exploitation campaigns. Attackers could leverage this vulnerability to compromise user accounts, inject malicious advertisements, or establish persistent backdoors through browser-based attacks that align with ATT&CK technique T1566 for phishing with malicious attachments or links.
The technical exploitation of this vulnerability requires minimal effort as attackers only need to construct malicious URLs containing script tags or JavaScript code within the cn parameter value. The lack of input validation or output encoding in the listads.php script means that any content submitted through this parameter is directly embedded into the HTML response without proper sanitization. This vulnerability demonstrates a critical failure in the application's security architecture where basic input validation controls are missing from the web application's data flow processing. Organizations should implement comprehensive input validation, output encoding, and Content Security Policy headers to prevent such vulnerabilities from being exploited in the wild. The weakness also indicates a broader need for security testing and code review practices that can identify and remediate similar flaws across the entire application stack, particularly focusing on parameters that are directly reflected in web responses without proper security controls.