CVE-2006-0860 in Guestbox
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in Michael Salzer Guestbox 0.6, and other versions before 0.8, allow remote attackers to inject arbitrary web script or HTML via (1) HTML tags that follow a "http://" string, which bypasses a regular expression check, and (2) other unspecified attack vectors.
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Analysis
by VulDB Data Team • 08/06/2017
The vulnerability identified as CVE-2006-0860 represents a critical cross-site scripting flaw affecting Michael Salzer Guestbox version 0.6 and earlier releases. This vulnerability stems from inadequate input validation mechanisms within the application's processing of user-supplied data, particularly when handling URLs and HTML content. The flaw manifests when the application fails to properly sanitize user input that contains hypertext transfer protocol references, creating an avenue for malicious actors to inject harmful scripts into web pages viewed by other users.
The technical implementation of this vulnerability involves a specific bypass mechanism that exploits a regular expression validation check designed to prevent XSS attacks. When users submit content containing strings that begin with "http://", the application's sanitization routine fails to properly handle subsequent HTML tags that follow these URL prefixes. This creates a loophole where attackers can craft malicious payloads that appear to be legitimate web addresses but actually contain embedded script tags or other harmful HTML elements. The bypass occurs because the regular expression pattern does not account for the specific sequence of characters that allows the malicious content to pass through the validation filters.
The operational impact of this vulnerability extends beyond simple script injection, as it enables attackers to execute arbitrary code within the context of users' browsers who view affected pages. This can result in session hijacking, credential theft, data exfiltration, and the potential for further exploitation through more sophisticated attack vectors. The vulnerability affects not only the guestbook functionality but could also compromise other areas of the web application where user input is processed and displayed. The widespread use of guestbook applications in web environments means that successful exploitation could affect numerous websites running vulnerable versions of this software.
Security professionals should note that this vulnerability aligns with CWE-79, which specifically addresses cross-site scripting flaws in web applications. The attack pattern demonstrates characteristics consistent with the ATT&CK framework's technique T1566, which covers "Phishing with Malicious Attachments" and related social engineering methods that exploit web application vulnerabilities. Organizations should implement immediate mitigations including input validation improvements, output encoding, and proper content sanitization. The most effective remediation involves upgrading to version 0.8 or later of the Guestbook software, which contains fixed validation routines that properly address the bypass mechanism. Additionally, implementing a web application firewall with XSS detection capabilities and conducting regular security assessments can help prevent exploitation of similar vulnerabilities in other web applications.