CVE-2006-1256 in PHP Guestbook
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in guestbook.php in Soren Boysen (SkullSplitter) PHP Guestbook 2.6 allows remote attackers to inject arbitrary web script or HTML via the url parameter.
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Analysis
by VulDB Data Team • 07/08/2021
The vulnerability identified as CVE-2006-1256 represents a classic cross-site scripting flaw within the PHP Guestbook application version 2.6 developed by Soren Boysen also known as SkullSplitter. This security weakness resides in the guestbook.php script where user input is not properly sanitized before being rendered back to web browsers. The specific vector of attack occurs through the url parameter which serves as an entry point for malicious actors to inject harmful scripts or HTML content into the web application's output.
This XSS vulnerability falls under the Common Weakness Enumeration category CWE-79 which specifically addresses improper neutralization of input during web page generation. The flaw enables attackers to execute malicious scripts in the context of the victim's browser session, potentially leading to session hijacking, credential theft, or unauthorized actions performed on behalf of authenticated users. The vulnerability is particularly concerning because it affects a guestbook application that typically allows unrestricted user submissions, making it a prime target for exploitation.
The operational impact of this vulnerability extends beyond simple script injection as it can be leveraged to create persistent XSS attacks that remain active until the malicious content is removed from the application's database. Attackers can craft malicious URLs that, when clicked by unsuspecting users, execute scripts that steal cookies, redirect users to malicious sites, or even modify the guestbook entries themselves. The persistent nature of guestbook entries means that the injected scripts can affect multiple users over time, amplifying the potential damage.
Mitigation strategies for CVE-2006-1256 should focus on implementing proper input validation and output encoding mechanisms. The most effective approach involves sanitizing all user-supplied input before processing or storing it in the database, with particular attention to the url parameter in this case. Implementing proper HTML entity encoding when displaying user content ensures that any potentially malicious scripts are rendered harmless. Additionally, employing a Content Security Policy (CSP) header can provide an additional layer of protection by restricting the sources from which scripts can be loaded. Organizations should also consider implementing input length limits and regular security audits of web applications to identify and remediate similar vulnerabilities. The vulnerability demonstrates the critical importance of proper input validation and output encoding practices as outlined in the OWASP Top Ten security principles and aligns with ATT&CK technique T1059.002 for command and scripting interpreter.