PROBLEM: Microsoft has identified a vulnerability that under certain conditions may cause a web server to send source code of certain types of web files to a visiting user. PLATFORM: All platforms running Microsoft Internet Information Server (IIS) 5.0 DAMAGE: If a user creates a specialized header and appends one of several particular characters at the end of the request, IIS will locate the correct file but not recognize it as a file that needs to be processed by a scripting engine. Instead, it will simply send the file to the browser. SOLUTION: Install the patch indicated below. For Windows 2000 install Service Pack 1.
VULNERABILITY The risk is LOW. If normal security recommendations regarding ASSESSMENT: .ASP files has been followed, there will be no sensitive information contained in the source code.
[Start of Microsoft Security Bulletin] Microsoft Security Bulletin (MS00-058) -------------------------------------- Patch Available for "Specialized Header" Vulnerability Originally posted: August 14, 2000 Summary ======= Microsoft has released a patch that eliminates a security vulnerability in Internet Information Server that ships with Microsoft(r) Windows 2000. Under certain conditions, the vulnerability could cause a web server to send the source code of certain types of web files to a visiting user. Frequently asked questions regarding this vulnerability and the patch can be found at http://www.microsoft.com/technet/security/bulletin/fq00-058.asp Issue ===== If an IIS server receives a file request that contains a specialized header as well as one of several particular characters at the end, the expected ISAPI extension processing may not occur. The result is that the source code of the file would be sent to the browser. It is important to note that normal security recommendations militate strongly against ever including sensitive information in .ASP files and, if these recommendations have been followed, there would be no sensitive information to compromise. The specialized header at issue here cannot be created via a standard Internet browser, so the request would need to be created by an alternate method. Affected Software Versions ========================== - Microsoft Internet Information Server 5.0 Patch Availability ================== - http://www.microsoft.com/Downloads/Release.asp?ReleaseID=23769 Note: This vulnerability is eliminated by installing Windows 2000 Service Pack 1 http://www.microsoft.com/windows2000/downloads/recommended/sp1/ We recommend that customers apply SP1 as the preferred option for eliminating this vulnerability, as it has been fully regression tested and includes fixes for additional issues. Note: Additional security patches are available at the Microsoft Download Center More Information ================ Please see the following references for more information related to this issue. - Frequently Asked Questions: Microsoft Security Bulletin MS00-058, http://www.microsoft.com/technet/security/bulletin/fq00-058.asp - Microsoft Knowledge Base article Q256888 discusses this issue and will be available soon. - Microsoft TechNet Security web site, http://www.microsoft.com/technet/security/default.asp - Obtaining Support on this Issue - This is a fully supported patch. Information on contacting Microsoft Product Support Services is available at http://support.microsoft.com/support/contact/default.asp Revisions ========= August 14, 2000: Bulletin Created. [End of Microsoft Security Bulletin]
Voice: +1 925-422-8193 (7 x 24) FAX: +1 925-423-8002 STU-III: +1 925-423-2604 E-mail: firstname.lastname@example.org World Wide Web: http://www.ciac.org/ http://ciac.llnl.gov (same machine -- either one will work) Anonymous FTP: ftp.ciac.org ciac.llnl.gov (same machine -- either one will work)