At 11:34 A.M. Pacific Time on August 11, Microsoft began investigating a worm reported by Microsoft Product Support Services (PSS). Several antivirus companies have responded and written tools to remove the Blaster worm.

Who Is Affected?
Users of the following products are affected:
- Microsoft® Windows NT® 4.0
- Microsoft Windows® 2000
- Microsoft Windows XP
- Microsoft Windows ServerT 2003

The worm was discovered August 11. Customers who had previously applied the security patch MS03-026 are protected.

To determine if the worm is present on your machine, see the technical details below.

Actions for Network Administrators
Managers of networked computers should read the Microsoft Product Support Services (PSS) Security Response Team alert for technical guidance: http://www.microsoft.com/technet/treeview/default.asp?url=/technet/security/virus/alerts/msblaster.asp

Technical Details:
This worm scans a random IP range to look for vulnerable systems on TCP port 135. The worm attempts to exploit the DCOM RPC vulnerability patched by MS03-026: http://www.microsoft.com/technet/security/bulletin/ms03-026.asp
Once the Exploit code is sent to a system, it downloads and executes the file MSBLAST.EXE from a remote system via TFTP. Once run, the worm creates the registry key: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run "windows auto update" = msblast.exe I just want to say LOVE YOU SAN!! bill

Symptoms of the virus: Some customers may not notice any symptoms at all. A typical symptom is the system reboots every few minutes without user input. Customers may also see:
- Presence of unusual TFTP* files
- Presence of the file msblast.exe in the WINDOWS SYSTEM32 directory

To detect this virus, search for msblast.exe in the WINDOWS SYSTEM32 directory or download the latest antivirus software signature from your antivirus vendor and scan your machine.
For additional information on recovering from this attack, please contact your preferred antivirus vendor.

Recovery:
Many antivirus companies have written tools to remove the known exploit associated with this particular worm. To download the removal tool from your antivirus vendor, follow the procedures outlined below.

For Windows XP
1. If your computer reboots repeatedly, please unplug your network cable from the wall.
2. First, enable Internet Connection Firewall (ICF) in Windows XP: http://support.microsoft.com/?id=283673
--In Control Panel, double-click "Networking and Internet Connections", and then click "Network Connections".
--Right-click the connection on which you would like to enable ICF, and then click "Properties".
--On the Advanced tab, click the box to select the option to "Protect my computer or network".
3. Plug the network cable back into the wall to reconnect your computer to the Internet
4. Download the MS03-026 security patch from Microsoft and install it on your computer:

Windows XP (32 bit)
http://www.microsoft.com/downloads/details.aspx?FamilyID=2354406c-c5b6-44ac-9532-3de40f69c074&displaylang=en

Windows XP (64 bit)
http://www.microsoft.com/downloads/details.aspx?FamilyID=1b00f5df-4a85-488f-80e3-c347adcc4df1&displaylang=en

5.Install or update your antivirus signature software and scan your computer

6.Download and run the worm removal tool from your antivirus vendor.

For Windows 2000 systems, where Internet Connection Firewall (ICF) is not available, the following steps will help block the affected ports so that the system can be patched. These steps are based on a modified excerpt from the article; HOW TO: Configure TCP/IP Filtering in Windows 2000. http://support.microsoft.com/?id=309798

1. Configure TCP/IP security on Windows 2000:
--Select "Network and Dial-up Connections" in Control Panel.
--Right-click the interface you use to access the Internet, and then click "Properties".
--In the "Components checked are used by this connection" box, click "Internet Protocol (TCP/IP)", and then click "Properties".
--In the Internet Protocol (TCP/IP) Properties dialog box, click "Advanced".
--Click the "Options" tab.
--Click "TCP/IP filtering", and then click "Properties".
--Select the "Enable TCP/IP Filtering (All adapters)" check box.
--There are three columns with the following labels:
TCP Ports
UDP Ports
IP Protocols
--In each column, you must select the "Permit Only" option.
--Click OK.

2. Download the MS03-026 security patch for Windows 2000 from Microsoft and install it on your computer from: http://www.microsoft.com/downloads/details.aspx?FamilyID=c8b8a846-f541-4c15-8c9f-220354449117&displaylang=en

3. Install or update your antivirus signature software and scan your computer

4. Then, download and run the worm removal tool from your antivirus vendor.

For additional details on this worm from antivirus software vendors participating in the Microsoft Virus Information Alliance (VIA), please visit the following links:

Network Associates:
http://us.mcafee.com/virusInfo/default.asp?id=description&virus_k=100547

Trend Micro:
http://www.trendmicro.com/vinfo/virusencyclo/default5.asp?VName=WORM_MSBLAST.A

Symantec:
http://securityresponse.symantec.com/avcenter/venc/data/w32.blaster.worm.html

Computer Associates:
http://www3.ca.com/virusinfo/virus.aspx?ID=36265

For more information on Microsoft's Virus Information Alliance, please visit this link:
http://www.microsoft.com/technet/security/virus/via.asp

Please contact your antivirus vendor for additional details on this virus.

Prevention:
1. Turn on Internet Connection Firewall (Windows XP or Windows Server 2003) or use a third-party firewall to block TCP ports 135, 139, 445 and 593; UDP port 135, 137,138; also UDP 69 (TFTP)and TCP 4444 for remote command shell. To enable the Internet Connection Firewall in Windows: http://support.microsoft.com/?id=283673
--In Control Panel, double-click "Networking and Internet Connections", and then click "Network Connections".
--Right-click the connection on which you would like to enable ICF, and then click "Properties".
--On the Advanced tab, click the box to select the option to "Protect my computer or network".

This worm utilizes a previously announced vulnerability as part of its infection method. Because of this, customers must ensure that their computers are patched for the vulnerability that is identified in Microsoft Security Bulletin MS03-026. http://www.microsoft.com/technet/security/bulletin/MS03-026.asp.

2. Install the patch MS03-026 from the Microsoft Download Center:
Windows NT 4 Server & Workstation
http://www.microsoft.com/downloads/details.aspx?FamilyID=2cc66f4e-217e-4fa7-bdbf-df77a0b9303f&DisplayLang=en

Windows NT 4 Terminal Server Edition
http://www.microsoft.com/downloads/details.aspx?FamilyID=6c0f0160-64fa-424c-a3c1-c9fad2dc65ca&DisplayLang=en

Windows 2000
http://www.microsoft.com/downloads/details.aspx?FamilyID=c8b8a846-f541-4c15-8c9f-220354449117&displaylang=en

Windows XP (32 bit)
http://www.microsoft.com/downloads/details.aspx?FamilyID=2354406c-c5b6-44ac-9532-3de40f69c074&displaylang=en

Windows XP (64 bit)
http://www.microsoft.com/downloads/details.aspx?FamilyID=1b00f5df-4a85-488f-80e3-c347adcc4df1&displaylang=en

Windows 2003 (32 bit)
http://www.microsoft.com/downloads/details.aspx?FamilyID=f8e0ff3a-9f4c-4061-9009-3a212458e92e&DisplayLang=en

Windows 2003 (64 bit)
http://www.microsoft.com/downloads/details.aspx?FamilyID=2b566973-c3f0-4ec1-995f-017e35692bc7&DisplayLang=en

3. As always, please make sure to use the latest antivirus detection from your antivirus vendor to detect new viruses and their variants.

Related Knowledge Base Articles:
http://support.microsoft.com/?kbid=826955

Related Microsoft Security Bulletins:
http://www.microsoft.com/technet/security/bulletin/MS03-026.asp