W32.Cherich@mm

SUMMARY

W32.Cherich@mm is a mass-mailing worm that uses Microsoft Outlook to send itself to all contacts that are in the Outlook Address Book. The email message has the following characteristics:

Subject: RE: E.Coli Outbreak
Message:
There is an outbreak of E.Coli (Escherichia Coli O157:H7) in Your Area!
The Article and how to find out if you have contracted the virus is attatched...
Attachment: Ecoli.exe

This threat is written in the Microsoft Visual Basic programming language and may be compressed with tElock.

Protection

• Virus Definitions (LiveUpdate™ Weekly) December 4, 2002
• Virus Definitions (Intelligent Updater) December 2, 2002

TECHNICAL DETAILS

When W32.Cherich@mm runs, it does the following,

It displays the following message:



It copies itself as

• C:WINDOWSSystem32Escherichia.exe
• C:WindowsEcoli.exe

It adds the value

ecoli C:WINDOWSSystem32Escherichia.exe

to the registry key

HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun

so that the worm runs when you start Windows.

The worm uses Microsoft Outlook to send itself to all contacts that are in the Outlook Address Book. The email message has the following characteristics:

Subject: RE: E.Coli Outbreak
Message:
There is an outbreak of E.Coli (Escherichia Coli O157:H7) in Your Area!
The Article and how to find out if you have contracted the virus is attatched...
Attachment: Ecoli.exe

If the current system day is 25, the worm displays a graphic.

Recommendations

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

NOTE: These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Update the virus definitions.
2. Restart the computer in Safe mode.
3. Run a full system scan, and delete all files that are detected as W32.Cherich@mm.
4. Delete the value
   
   ecoli C:WINDOWSSystem32Escherichia.exe
   
   from the registry keys
   
   HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
   

For details on how to do this, read the following instructions.

To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:

• Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
• Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.
  
  Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

To restart the computer in Safe mode:
All Windows 32-bit operating systems, except Windows NT, can be restarted in Safe mode. For instructions on how to do this, read the document How to start the computer in Safe Mode.

To scan for and delete the infected files:

1. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
   • Norton AntiVirus consumer products: Read the document How to configure Norton AntiVirus to scan all files.
   • Symantec enterprise antivirus products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
2. Run a full system scan.
3. If any files are detected as infected with W32.Cherich@mm, click Delete.

To delete the values that the worm added to the registry:

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
   
   CAUTION: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.
   
3. Navigate to the key
   
   HKEY_CURRENT_USERSOFTWAREMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the value
   
   ecoli C:WINDOWSSystem32Escherichia.exe
   
5. Exit the Registry Editor.