Microsoft ASP.NET Framework bypass security
| ms-aspnet-security-bypass (17644) |  Medium Risk |
Description:
Microsoft ASP.NET Framework could allow a remote attacker to bypass security restrictions, caused by a canonicalization vulnerability. The web.config file prevents access to files unless a user is properly authenticated. A remote attacker could use Mozilla and send a specially-crafted URL request containing a backslash (\) or use Microsoft Internet Explorer to send a request containing a URL encoded backslash (%5C) to bypass this authentication method and gain unauthorized access to the restricted resource.
Platforms Affected:
- Microsoft, .NET Framework 1.0
- Microsoft, .NET Framework 1.1
- Microsoft, ASP.NET
- Microsoft, Windows 2000 SP3
- Microsoft, Windows 2000 SP4
- Microsoft, Windows 2003 Server
- Microsoft, Windows XP SP2
- Microsoft, Windows XP SP1
- Microsoft, Windows XP Tablet PC
- Microsoft, Windows XP Media Center
Remedy:
Download the ASP.NET HTTP module, available from the Microsoft Corporation Web site. See References.
For Microsoft Windows:
Apply the appropriate patch for your system, as listed in the latest Microsoft Security Bulletin. See References.
— OR —
Use Microsoft Automatic Update if it is supported by your operating system. The original bulletin issued by Microsoft has been superseded.
Consequences:
Bypass Security
References:
- CIAC Information Bulletin P-127, Microsoft ASP.NET Path Validation Vulnerability at http://www.ciac.org/ciac/bulletins/p-127.shtml.
- Microsoft Corporation Web site, Microsoft ASP.NET ValidatePath Module at http://www.microsoft.com/downloads/details.aspx?familyid=DA77B852-DFA0-4631-AAF9-8BCC6C743026&displaylang=en.
- Microsoft Knowledge Base Article 887459, Programmatically check for canonicalization issues with ASP.NET at http://support.microsoft.com/?kbid=887459.
- Microsoft Security Bulletin MS05-004, ASP.NET Path Validation Vulnerability (887219) at http://www.microsoft.com/technet/security/bulletin/ms05-004.mspx.
- Microsoft Security Bulletin MS07-040, Vulnerabilities in .NET Framework Could Allow Remote Code Execution (931212) at http://www.microsoft.com/technet/security/bulletin/ms07-040.mspx.
- NTBugTraq Mailing List, Thu Oct 07 2004 - 22:12:21 CDT, More details on ASP.NET vulnerability at http://archives.neohapsis.com/archives/ntbugtraq/2004-q4/0028.html.
- NTBugTraq Mailing List, Tue Sep 14 2004 - 06:42:28 CDT , Security bug in .NET Forms Authentication at http://archives.neohapsis.com/archives/ntbugtraq/2004-q3/0221.html.
- BID-11342: Microsoft ASP.NET URI Canonicalization Unauthorized Web Access Vulnerability
- CVE-2004-0847: The Microsoft .NET forms authentication capability for ASP.NET allows remote attackers to bypass authentication for .aspx files in restricted directories via a request containing a (1) \ (backslash) or (2) %5C (encoded backslash), aka Path Validation Vulnerability.
- US-CERT VU#283646: Microsoft ASP.NET fails to perform proper canonicalization
Reported:
Sep 14, 2004
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