CVE-2006-0472 in my little guestbook
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in guestbook.php in my little homepage my little guestbook, as last modified in March 2004, allows remote attackers to inject arbitrary Javascript via a javascript URI in BBcode link tags.
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Analysis
by VulDB Data Team • 08/04/2017
This cross-site scripting vulnerability exists in my little homepage my little guestbook software, specifically within the guestbook.php script that was last modified in March 2004. The flaw represents a classic client-side injection vulnerability that enables remote attackers to execute malicious javascript code within the context of other users' browsers. The vulnerability manifests when the application fails to properly sanitize user input that is processed through BBcode link tags, allowing attackers to embed javascript URIs that get executed when other users view the guestbook entries. This type of vulnerability falls under CWE-79 which specifically addresses cross-site scripting flaws where applications fail to validate or escape user-controllable data before incorporating it into dynamically generated web pages.
The technical exploitation occurs when an attacker creates a guestbook entry containing a BBcode link tag with a javascript URI in the href attribute. When other users browse the guestbook, their browsers execute the embedded javascript code, potentially leading to session hijacking, credential theft, or redirection to malicious sites. The vulnerability is particularly dangerous because it leverages the trust relationship between the web application and its users, allowing malicious code to run in the context of legitimate user sessions. This attack vector aligns with ATT&CK technique T1566.001 which covers spearphishing attachments, though in this case the attack occurs through the guestbook entry itself rather than an attachment.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable more sophisticated attacks such as credential harvesting through form submissions, cookie theft via document.cookie access, or redirection to phishing sites. Attackers can craft malicious entries that appear legitimate to users, making detection difficult and increasing the likelihood of successful exploitation. The vulnerability affects any user who views the guestbook entries containing the malicious code, potentially compromising numerous user sessions and leading to unauthorized access to personal information or system resources. Organizations using this software would need to implement input validation and output encoding mechanisms to prevent the execution of untrusted content, with the most effective mitigation being proper sanitization of all user inputs before rendering them in web pages.
The vulnerability demonstrates the critical importance of input validation in web applications, particularly when dealing with user-generated content that gets displayed to other users. Modern secure coding practices would require implementing strict validation of BBcode attributes, particularly href values, and ensuring that any javascript protocols are either blocked or properly escaped before output to the browser. This vulnerability also highlights the need for regular security updates and the dangers of using outdated web applications that may contain known security flaws. Organizations should implement comprehensive security testing procedures including dynamic application security testing and regular code reviews to identify and remediate such vulnerabilities before they can be exploited in real-world scenarios.