Frequently asked questions regarding this vulnerability can be found at http://www.microsoft.com/security/bulletins/MS00-005faq.asp.

Issue
RTF files consist of text and control information. The control information is specified via directives called control words. The default RTF reader that ships as part of many Windows platforms has an unchecked buffer in the portion of the reader that parses control words. If an RTF file contains a specially-malformed control word, it could cause the application to crash.

Microsoft believes that this is a denial of service vulnerability only, and that there is no capability to use this vulnerability to run arbitrary code. The most serious risk from this vulnerability would result if a user had preview mode enabled on a mail program like Outlook, and received an email that exploited the vulnerability. Because preview mode causes the mail to be parsed without user assent, the mail program would continue to crash until a subsequent mail was received or the mail program was started with preview mode disabled.

Affected Software Versions

• Microsoft Windows 95
• Microsoft Windows 98
• Microsoft Windows 98 Second Edition
• Microsoft Windows NT 4.0 Workstation
• Microsoft Windows NT 4.0 Server
• Microsoft Windows NT 4.0 Server, Enterprise Edition
• Microsoft Windows NT 4.0 Server, Terminal Server Edition

NOTE: Windows 2000 is not affected by this vulnerability.

Patch Availability

• Windows 95:
  http://www.microsoft.com/windows95/downloads/contents/WUCritical/rtfcontrol/default.asp
  
  
• Window 98:
  http://www.microsoft.com/windows98/downloads/contents/WUCritical/rtfcontrol/default.asp
  

Windows NT 4.0 Workstation, Windows NT 4.0 Server, and Windows NT 4.0 Server, Enterprise Edition:

• Intel:
  http://www.microsoft.com/Downloads/Release.asp?ReleaseID=17510
  
  
• Alpha:
  http://www.microsoft.com/Downloads/Release.asp?ReleaseID=17511
  

NOTE: The Windows 95 and 98 versions of the patch will also be available via WindowsUpdate shortly. When this happens, we will modify the bulletin to note this fact.

NOTE: Additional security patches are available at the Microsoft Download Center (www.microsoft.com/downloads)

More Information
Please see the following references for more information related to this issue.

• Microsoft Security Bulletin MS00-005: Frequently Asked Questions: Frequently Asked Questions, http://www.microsoft.com/security/bulletins/MS00-005faq.asp.
  
  
• Microsoft Knowledge Base (KB) article Q249973, Default RTF File Viewer Interrupts Normal Application Processing, http://support.microsoft.com/support/kb/articles/q249/9/73.asp.
  
  
• Rich Text Format (RTF) Specification and Sample RTF Reader Program, Version 1.5, http://msdn.microsoft.com/library/specs/richtextformatrtfspecificationsamplertfreaderprogramversion15.htm
  
  
• Microsoft Security Advisor web site, http://www.microsoft.com/security/default.asp.

Obtaining Support on this Issue
This is a fully supported patch. Information on contacting Microsoft Technical Support is available at: http://support.microsoft.com/support/contact/default.asp

Microsoft Security Bulletin (MS00-003)

Patch Available for "Spoofed LPC Port Request" Vulnerability

Date: January 13, 2000

Summary
Microsoft has released a patch that eliminates a security vulnerability in Microsoft(r) Windows NT(r) 4.0. The vulnerability could allow a user logged onto a Windows NT 4.0 machine from the keyboard to become an administrator on the machine.