CVE-2005-2853 in GuppY
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in GuppY 4.5.3a and earlier allow remote attackers to inject arbitrary web script or HTML via (1) the pg parameter to printfaq.php, or the (2) Referer or (3) User-Agent HTTP headers, which are not properly handled by error.php.
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Analysis
by VulDB Data Team • 06/10/2019
The vulnerability described in CVE-2005-2853 represents a critical cross-site scripting flaw affecting GuppY version 4.5.3a and earlier installations. This issue stems from inadequate input validation and sanitization mechanisms within the web application's error handling routines. The vulnerability manifests across multiple attack vectors, making it particularly dangerous as it provides attackers with several potential entry points to execute malicious code within the context of users' browsers.
The technical flaw occurs when the application fails to properly sanitize user-supplied input before incorporating it into dynamically generated web pages. Specifically, the vulnerability affects three distinct input sources: the pg parameter passed to printfaq.php, as well as the Referer and User-Agent HTTP headers that are processed by error.php. These parameters are directly embedded into the application's output without appropriate encoding or validation, creating opportunities for attackers to inject malicious JavaScript code or HTML content. The vulnerability is classified as a classic XSS flaw under CWE-79, which specifically addresses improper neutralization of input during web page generation.
The operational impact of this vulnerability extends beyond simple data theft or defacement. Attackers can leverage these XSS flaws to establish persistent sessions, redirect users to malicious sites, steal session cookies, or even perform actions on behalf of authenticated users. The presence of multiple attack vectors increases the exploitability of the vulnerability, as an attacker only needs to find one of the three entry points to compromise the application. This weakness particularly affects web applications that rely heavily on user input for content generation and error reporting, as demonstrated by the GuppY CMS's handling of HTTP headers in its error.php script.
Mitigation strategies for this vulnerability should focus on implementing comprehensive input validation and output encoding mechanisms throughout the application. The most effective approach involves sanitizing all user-supplied data before it is processed or displayed, particularly in error handling routines where such vulnerabilities commonly occur. Organizations should implement proper HTML encoding for all dynamic content, utilize Content Security Policy headers to restrict script execution, and ensure that HTTP headers are properly validated before being incorporated into web responses. The remediation efforts should align with ATT&CK technique T1566, which addresses the exploitation of web application vulnerabilities, and should be part of broader security practices outlined in the OWASP Top Ten. Regular security assessments and code reviews should be conducted to identify similar input validation weaknesses in other parts of the application stack, particularly in error handling and parameter processing components.