CVE-2005-4727 in gbook
Summary
by MITRE
Cross-site scripting (XSS) vulnerability in gbook.cgi in gBook before 1.0.2 allows remote attackers to inject arbitrary web script or HTML via the User-Agent HTTP header field.
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Analysis
by VulDB Data Team • 07/16/2018
The vulnerability described in CVE-2005-4727 represents a classic cross-site scripting flaw within the gBook application's gbook.cgi component. This issue affects versions prior to 1.0.2 and demonstrates how seemingly innocuous HTTP header fields can become attack vectors when proper input validation and output sanitization are absent from web applications. The vulnerability specifically targets the User-Agent HTTP header field, which is commonly used by web servers to identify client software and characteristics during HTTP requests.
The technical flaw stems from the application's failure to properly sanitize or escape user input received through the User-Agent header before displaying it within web pages. When an attacker crafts a malicious User-Agent string containing embedded script tags or HTML code, the vulnerable application processes this input without adequate filtering mechanisms. This oversight creates a condition where injected malicious code gets executed in the context of other users' browsers who subsequently access pages that display the User-Agent information. The vulnerability operates under the CWE-79 principle of inadequate input validation and represents a type of reflected XSS attack where the malicious payload is reflected back to users through the application's response mechanism.
The operational impact of this vulnerability extends beyond simple script execution, as it can enable attackers to perform various malicious activities including session hijacking, credential theft, data exfiltration, and redirection to malicious websites. Since the vulnerability is accessible through the HTTP User-Agent header, attackers can potentially exploit it without requiring direct interaction with the application's user interface or specific form inputs. This makes the vulnerability particularly dangerous as it can be triggered by automated scanning tools or by simply accessing the vulnerable application with a specially crafted HTTP request. The attack vector is further amplified by the fact that User-Agent headers are commonly processed and displayed in web applications, making this a widespread potential exposure point.
Mitigation strategies for this vulnerability require immediate implementation of proper input sanitization and output encoding practices within the gBook application. The most effective approach involves implementing strict validation of all HTTP headers, particularly those that may be displayed in web pages, and applying appropriate HTML escaping or encoding before rendering any user-provided content. Organizations should implement a comprehensive input validation framework that rejects or sanitizes potentially malicious content in all HTTP headers. Additionally, the application should be updated to version 1.0.2 or later where this vulnerability has been addressed through proper input sanitization mechanisms. The fix should align with ATT&CK technique T1566.001 for credential access through web application vulnerabilities and follows security best practices outlined in OWASP Top 10 for preventing XSS attacks through proper input validation and output encoding. Regular security testing including HTTP header validation should be implemented to prevent similar vulnerabilities from emerging in other components of the application stack.