Microsoft KB Archive/842168

= Incoming ARP packets can overwrite static entries in the ARP cache in Windows 2000 =

Article ID: 842168

Article Last Modified on 10/26/2006

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APPLIES TO


 * Microsoft Windows 2000 Server
 * Microsoft Windows 2000 Professional Edition
 * Microsoft Windows 2000 Advanced Server

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SYMPTOMS
In Microsoft Windows 2000, incoming Address Resolution Protocol (ARP) packets can overwrite static entries in the ARP cache if the sender's protocol address matches an existing static entry that is in the ARP cache. Because an ARP reply that is received without an ARP request can update the ARP cache, a static ARP entry can be spoofed by using a false media access control (MAC) address. Because ARP is unlikely to be routed, this situation may occur only on a local network.



CAUSE
This problem occurs because the ARP client does not distinguish between transient and static cache entries when the ARP client processes incoming ARP packets.



Hotfix information
A supported hotfix is now available from Microsoft, but it is only intended to correct the problem that this article describes. Apply it only to systems that are experiencing this specific problem.

To resolve this problem, contact Microsoft Product Support Services to obtain the hotfix. For a complete list of Microsoft Product Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites
This hotfix requires Windows 2000 Service Pack 4 (SP4).

Restart requirement
You must restart your computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel. Date        Time   Version         Size    File name 19-Jun-2003 20:05  5.0.2195.6602  108,816  Msafd.dll 02-Jun-2004 22:44  5.0.2195.6938  318,832  Tcpip.sys 19-Jun-2003 20:05  5.0.2195.6601   17,680  Wshtcpip.dll 19-Jun-2003 20:05  5.0.2195.6687  120,240  Afd.sys 19-Jun-2003 20:05  5.0.2195.6655   16,240  Tdi.sys



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
For additional information about how hotfix packages are named, click the following article number to view the article in the Microsoft Knowledge Base:

816915 New file naming schema for Microsoft Windows software update packages

For more information about standard terminology that is used to describe Microsoft software updates, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional query words: hotfix arp poisoning

Keywords: kbqfe kbhotfixserver kbbug kbfix kbwin2000presp5fix KB842168

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