Microsoft Advises IIS Administrators on Code Red

The Microsoft Security Response Center, along with other organizations listed below, is jointly publishing this alert that ALL IIS ADMINISTRATORS ARE ASKED TO READ

A Very Real and Present Threat to the Internet:

July 31 Deadline For Action


The Code Red Worm and mutations of the worm pose a continued and serious threat to Internet users. Immediate action is required to combat this threat. Users who have deployed software that is vulnerable to the worm (Microsoft IIS Versions 4.0 and 5.0) must install, if they have not done so already, a vital security patch.

How Big Is The Problem?

On July 19, the Code Red worm infected more than 250,000 systems in just 9 hours. The worm scans the Internet, identifies vulnerable systems, and infects these systems by installing itself. Each newly installed worm joins all the others causing the rate of scanning to grow rapidly. This uncontrolled growth in scanning directly decreases the speed of the Internet and can cause sporadic but widespread outages among all types of systems. Code Red is likely to start spreading again on July 31st, 2001 8:00 PM EDT and has mutated so that it may be even more dangerous. This spread has the potential to disrupt business and personal use of the Internet for applications such as electronic commerce, email and entertainment.

Who Must Act?

Every organization or person who has Windows NT or Windows 2000 systems AND the IIS web server software may be vulnerable. IIS is installed automatically for many applications. If you are not certain, follow the instructions attached to determine whether you are running IIS 4.0 or 5.0. If you are using Windows 95, Windows 98, or Windows Me, there is no action that you need to take in response to this alert.

What To Do If You Are Vulnerable?

a. To rid your machine of the current worm, reboot your computer.

b. To protect your system from re-infection:

Install Microsoft’s patch for the Code Red vulnerability problem:

– – Windows NT version 4.0:

– – Windows 2000 Professional, Server and Advanced Server:

Step-by-step instructions for these actions are posted at

Microsoft’s description of the patch and its installation, and the vulnerability it addresses is posted at: url=/technet/security/bulletin/MS01-033.asp

Because of the importance of this threat, this alert is being made jointly by:


The National Infrastructure Protection Center

Federal Computer Incident Response Center (FedCIRC)

Information Technology Association of America (ITAA)

CERT Coordination Center

SANS Institute

Internet Security Systems

Internet Security Alliance

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