CVE-2006-7192 in .NET Framework
Summary
by MITRE
Microsoft ASP .NET Framework 2.0.50727.42 does not properly handle comment (/* */) enclosures, which allows remote attackers to bypass request filtering and conduct cross-site scripting (XSS) attacks, or cause a denial of service, as demonstrated via an xss:expression STYLE attribute in a closing XSS HTML tag.
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Analysis
by VulDB Data Team • 07/14/2021
The vulnerability identified as CVE-2006-7192 affects Microsoft ASP.NET Framework version 2.0.50727.42 and represents a significant security flaw in the framework's handling of HTML comment syntax. This issue stems from improper processing of comment enclosures denoted by the forward slash asterisk pattern / / which are commonly used in HTML and CSS to create multi-line comments. The flaw exists within the framework's request filtering mechanism that is designed to prevent malicious input from being processed by web applications. When the ASP.NET framework encounters HTML comment syntax in user-supplied input, it fails to properly sanitize or validate the content, creating an avenue for attackers to bypass security controls that should otherwise prevent malicious code execution.
The technical exploitation of this vulnerability occurs through the manipulation of HTML elements that contain CSS expressions within style attributes. Specifically, attackers can craft malicious input containing an xss:expression STYLE attribute within a closing XSS HTML tag, leveraging the framework's insufficient handling of comment enclosures. This allows malicious code to be embedded in a way that circumvents the normal input validation processes that should prevent cross-site scripting attacks. The vulnerability specifically targets the framework's inability to properly parse and filter HTML comments when they appear within CSS style attributes, creating a bypass condition that can be exploited to inject malicious JavaScript code into web pages.
The operational impact of this vulnerability is substantial as it enables multiple attack vectors that can severely compromise web application security. Remote attackers can execute cross-site scripting attacks by injecting malicious code that gets executed in the context of other users' browsers, potentially leading to session hijacking, data theft, or unauthorized actions performed on behalf of victims. Additionally, the vulnerability can be leveraged to cause denial of service conditions by crafting malformed input that triggers unexpected behavior in the ASP.NET processing pipeline. The bypass of request filtering mechanisms means that traditional security controls designed to prevent XSS attacks become ineffective, rendering web applications vulnerable to persistent exploitation attempts.
Organizations affected by this vulnerability should implement immediate mitigations including updating to patched versions of the Microsoft ASP.NET Framework, applying the relevant security updates released by Microsoft, and implementing additional input validation measures beyond the default framework protections. The vulnerability aligns with CWE-79 which describes improper neutralization of input during web page generation, and relates to ATT&CK technique T1059.007 for command and scripting interpreter using scriptlets. Security teams should also consider implementing web application firewalls that can detect and block suspicious comment patterns in user input, as well as conducting thorough code reviews to ensure that applications are not relying solely on framework-level protections. The incident highlights the importance of comprehensive input validation and the potential consequences of insufficient sanitization of special characters in web applications.