Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":
Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
If a blended threat exploits one or more network services, disable, or block access to, those services until a patch is applied.
Always keep your patch levels up-to-date, especially on computers that host public services and are accessible through the firewall, such as HTTP, FTP, mail, and DNS services (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
Enforce a password policy. Complex passwords make it difficult to crack password files on compromised computers. This helps to prevent or limit damage when a computer is compromised.
Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
Isolate infected computers quickly to prevent further compromising your organization. Perform a forensic analysis and restore the computers using trusted media.
Train employees not to open attachments unless they are expecting them. Also, do not execute software that is downloaded from the Internet unless it has been scanned for viruses. Simply visiting a compromised Web site can cause infection if certain browser vulnerabilities are not patched.
Removal using the W32.Esbot Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Esbot.A. Use this removal tool first, as it is the easiest way to remove this threat.
Manual Removal:
The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.
Anti-virus software publisher Symantec has reported that outbreaks of two varieties of worm are imminent following system failures on two unnamed major corporate networks in the United Kingdom. After receiving several eyewitness accounts from on-site personnel this reporter noted similarities to the MSBlast worm which made headline news two years ago (on the 16th of July 2003) after causing massive outages. 

The worms are limited to Microsoft Windows products based on the NT architecture such as Windows 2000 or Windows XP, exploiting administrator services applets which shut a computer down when a certain service fails. The worms cause these "administrator services" to fail, provoking the computer into shutting down immediately. 

Microsoft has announced that a critical update is available for all users, even
for those who use pirated versions of Windows.

Chrysler, Kraft Foods and many other US corporations are feeling the brunt of the attack as the US was in the middle of the work day when new more virulent variants emerged.