CVE-2006-0846 in Web Blog
Summary
by MITRE
Multiple cross-site scripting (XSS) vulnerabilities in Leif M. Wright s Blog 3.5 allow remote attackers to inject arbitrary web script or HTML via the (1) Referer and (2) User-Agent HTTP headers, which are stored in a log file and not sanitized when the administrator views the "Log" page, possibly using the ViewCommentsLog function.
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Analysis
by VulDB Data Team • 08/02/2017
This vulnerability resides in the Leif M. Wright s Blog 3.5 application where multiple cross-site scripting flaws exist due to inadequate input sanitization of HTTP headers. The flaw specifically affects the logging mechanism where the Referer and User-Agent HTTP headers are stored without proper sanitization before being displayed on the administrator's Log page. When administrators view the log file through the ViewCommentsLog function, the unsanitized header content is rendered directly into the web page, creating a persistent cross-site scripting vector. The vulnerability demonstrates a classic input validation and output encoding failure where user-controllable data enters the application through legitimate HTTP headers and is subsequently displayed without proper context-appropriate escaping or sanitization. This represents a type of server-side cross-site scripting vulnerability that allows attackers to inject malicious scripts into web pages viewed by administrators, potentially enabling session hijacking, credential theft, or further privilege escalation within the application.
The technical implementation of this vulnerability stems from the application's failure to properly validate and sanitize HTTP headers before storing and displaying them in the administrative interface. The Referer and User-Agent headers are typically considered trusted application inputs but in this case they become attack vectors because the application treats them as untrusted data that requires sanitization. When these headers contain malicious script payloads, they are logged verbatim and subsequently executed in the context of the administrator's browser when viewing the log page. This vulnerability aligns with CWE-79 which describes improper neutralization of input during web page generation, specifically manifesting as a server-side XSS flaw where the application itself becomes the vector for script injection. The vulnerability operates at the intersection of web application security principles and HTTP header handling, where legitimate application functionality becomes compromised due to insufficient data sanitization.
The operational impact of this vulnerability is significant as it provides remote attackers with a persistent means of executing arbitrary code in the context of administrator sessions. An attacker could craft malicious Referer or User-Agent headers containing script payloads that would execute whenever the administrator views the log page, potentially leading to complete system compromise. The vulnerability is particularly dangerous because it leverages legitimate administrative functionality to deliver the attack payload, making detection more difficult and increasing the likelihood of successful exploitation. The attacker does not need to directly interact with the vulnerable application interface but can simply visit a page that generates the appropriate HTTP headers, making this a passive attack vector. This vulnerability enables a range of malicious activities including session hijacking, data exfiltration, and privilege escalation, all of which can be achieved through the administrator's privileged browser context.
Mitigation strategies for this vulnerability require implementing proper input sanitization and output encoding mechanisms throughout the application's data flow. The most effective approach involves sanitizing all HTTP header data before storage and ensuring that any data displayed in administrative interfaces undergoes context-appropriate escaping before rendering. Implementing a Content Security Policy that restricts script execution can provide additional defense in depth. The application should employ proper input validation to reject suspicious header content and utilize output encoding techniques such as HTML entity encoding when displaying stored header data. Additionally, implementing least privilege principles for administrative access and regular monitoring of log files can help detect anomalous header content. This vulnerability highlights the importance of treating all user-controllable data as potentially malicious and demonstrates the critical need for comprehensive input validation and output encoding practices. Organizations should ensure that all HTTP headers are properly sanitized regardless of their source, as these headers can be manipulated by attackers to bypass traditional security controls and deliver malicious payloads through legitimate application functionality. The vulnerability also underscores the need for regular security assessments of application logging mechanisms to identify similar issues in other components that may store and display user-controllable data.