JS.KakWorm.G

SUMMARY

Norton AntiVirus detects this as JS.KakWorm.G on incoming email.

Protection

• Virus Definitions (Intelligent Updater) March 7, 2001

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 3 - 9
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Difficult

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

For technical information, see the Wscript.Kakworm writeup.

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

There is more than one way to remove this worm:

• Use the Wscript.Kakworm Repair Tool created by the Symantec AntiVirus Research Center. This is the preferred method for repairing the damage done by the worm in most cases.
• Repair the damage manually. In most cases it can be removed in Safe Mode. Please see Solution 1 for information on how to do this. If this does not resolve the problem, or if you prefer to work in MS-DOS mode, then please see Solution 2.
  
  NOTE: The procedure described in this document is complex and assumes that you are familiar with basic Windows and DOS procedures. If you are not, then we suggest that you obtain the services of a qualified computer consultant.

Solution 1 -- How to remove this worm from within Windows
Here is a list of steps to remove the worm. Detailed instructions follow:

• Restart the computer in Safe Mode.
• Enable show all files.
• Find and delete the dem.*, *.dem, and *.hta files.
• Remove the worm entry from the Autoexec.bat file.
• Remove the worm entry from the registry.
• Disable or uninstall the Windows Scripting Host, or enable Script Blocking (NAV 2001 only)
• Delete infected files from Quarantine.
• Clear deleted items folder.
• Install the Microsoft patch.
• Take action after installing the Microsoft patch.

To restart the computer in Safe Mode:

• If you are running Windows 95, follow these steps:
  1. Exit all programs, and then shut down the computer.
  2. Turn off the power and wait 30 seconds. You must turn off the power to remove the virus from memory. Do not press the reset button.
  3. Press F8 when you see the message "Starting Windows 95."
  4. Press the number that corresponds to Safe Mode, and then press Enter.
• If you are running Windows 98, follow these steps:
  1. Click Start, and click Run.
  2. Type msconfig and then Click OK. The System Configuration Utility dialog box appears.
  3. Click Advanced on the General tab.
  4. Check Enable Startup Menu, click OK, and click OK again.
  5. Exit all programs, and then shut down the computer.
  6. Turn off the power and wait 30 seconds. You must turn off the power to remove the virus from memory. Do not press the reset button.
  7. Turn on the computer, and wait for the menu.
  8. Press the number that corresponds to Safe Mode, and then press Enter.

To enable show all files:
Follow these steps to make sure that Windows is set to show all files:

1. Start Windows Explorer.
2. Click the View menu (or the Tools menu in Windows Me), and click Options or Folder options.
3. Click the View tab, and make sure that "Hide file extensions for known file types" is unchecked.
4. Do one of the following:
   • Windows 95/98 - Under the "Hidden files" folder, click Show all files.
   • Windows Me - Uncheck "Hide protected operating system files," and under the "Hidden files" folder click "Show hidden files and folders."
5. Click Apply, and then click OK.

To find and delete worm files:

1. Click Start, point to Find, and click Files or Folders.
2. Make sure that Look in is set to (C:) and that Include subfolders is checked.
3. Type dem.* in the Named box, and then click Find Now.
4. In the results pane, select each displayed file, press Delete, and then click Yes to confirm.
5. Click New Search.
6. Make sure that Look in is set to (C:) and that Include subfolders is checked.
7. Type *.dem in the Named box, and then click Find Now.
8. Select each file in the results pane, press Delete, and then click Yes to confirm.
9. Click New Search.
10. Make sure that Look in is set to (C:) and that Include subfolders is checked.
11. Type *.hta in the Named box, and then click Find Now.
12. Select each file in the results pane, press Delete, and then click Yes to confirm.
13. Right-click the Recycle Bin icon on the desktop, and click Empty Recycle Bin.

To remove the worm entry from the Autoexec.bat file:

1. Click Start, and click Run. The Run dialog box appears.
2. Type sysedit and then click OK. The System Configuration Editor opens.
3. Click the Autoexec.bat window.
4. Locate and delete the line that reads
   
   C:WindowsStart MenuProgramsStartUpDEM.hta

NOTE: Some variants of this worm insert one or both of the following lines instead of or in addition to the previous text. If you see either of these lines--or any line that refers to dem--then it should be deleted.

@echo off C:WindowsSTARTM~1ProgramsStartUpDEM.hta
Del C:WindowsSTARTM~1ProgramsStartUpDEM.hta

5. Because some variants hide the dem entry elsewhere in the Autoexec.bat file, search the file to make sure that no entries have been missed:

1. Make sure that the cursor is positioned at the beginning of the Autoexec.bat file.
2. Click Search, and click Find.
3. Type dem in the Find box, and then click Next.
   • If you see the message, "Cannot find dem," then proceed to the next step.
   • If an entry is found that contains dem, delete it, and then press the F3 key to repeat the search. Keep repeating the search until all references to dem have been removed and you see the message "Cannot find dem." Exit the System Editor, and then click Yes to save changes.

To remove the worm entry from the registry:

CAUTION: We strongly recommend that you back up the Windows registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure that you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to and click the following key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoft
   WindowsCurrentVersionRun
   
   NOTE: If you are running Windows 98, in addition to the Run key, perform the next step on the Run- key if it exists. (The Run- key will exist only if you have used the System Configuration Utility to disable programs loading from the registry.)
   
4. Look for the following String value in the right pane:
   
   Demoniacal "C:WINDOWSSYSTEM(name).hta"
   
5. If it exists, click it, press Delete, and then click Yes to confirm.
6. Navigate to and click the following key:
   
   HKEY_CURRENT_USERIdentities<Identity>Software
   MicrosoftOutlook Express5.0Signatures
   
   NOTES:
   • The <Identity> key will be different on each computer. It is a long string of numbers and letters in brackets, similar to {2F3FF060-E5E4-11D3-B5CD-CC519BEAAC42}
   • Make sure that you go all of the way down through the keys and that you select the Signatures subkey. Do not delete the Identities key itself.
     
7. Press Delete, and then click Yes to confirm.
8. Exit Registry Editor, and then restart the computer.
   
   NOTE: (For Windows 98 users only) Before restarting, if you used the Microsoft System Configuration Utility to enable the Startup menu, you can disable it at this time. Follow these steps:
   1. Click Start, and click Run.
   2. Type msconfig and then Click OK. The System Configuration Utility dialog box appears.
   3. Click Advanced on the General tab.
   4. Uncheck Enable Startup Menu, click OK, and then click OK again.
   5. Restart the computer.

To disable, uninstall, or block malicious scripts used by the Windows Scripting Host:
The Microsoft Windows Scripting Host enables you to run Visual Basic Scripting and JScript within Windows. Most programs do not use this scripting. Because several worms, including JS.KakWorm.G have made use of this scripting, you may want to take additional steps to prevent the spread of infection by worms that make use of it.

• If you are using Norton AntiVirus 2001, a free program update is available that includes Script Blocking is available. To obtain it, please run LiveUpdate.
• For other versions of Norton AntiVirus, SARC offers a tool to disable the Windows Scripting Host.

To delete worm-infected files from Quarantine:
The files that were infected by JS.KakWorm.G are no longer necessary on your system. To permanently delete these infected files, see the document How to remove files from Norton AntiVirus Quarantine.

To clear the deleted items folder:
If you do not have Outlook or Outlook Express set to clear deleted email when you close the program, then clear this folder before you send or receive email.

CAUTION: Before you do this, turn off the preview pane option. If you do not, then you risk reinfection.

• In Microsoft Outlook, click the View menu and make sure that the Preview Pane menu item is not selected.
• In Outlook Express, click the View menu, and click Layout. Uncheck Show Preview Pane.

To install the Microsoft patch:
If you have not already done so, install the Microsoft Scripting update, which is available at http://www.microsoft.com/technet/ie/tools/scrpteye.asp.

For help with this, see the document How to download and install the Microsoft Scripting update.

What to do after installing the Microsoft patch
After you have removed the worm and installed the Microsoft security patch, do the following any time that NAV detects an email message infected with JS.KakWorm.G:

1. Note which specific message is infected.
2. Click "Ignore the problem and continue with the infected file."
   
   NOTE: Any other action will disrupt the message index, and the downloaded messages will not be cleaned from the email server. The next time that you download mail, you will have all of the previous message including those infected with JS.KakWorm.G.
   
3. When you open or preview the infected message, you will see the message "An active X control on this page is not safe: Your current security settings prohibit running unsafe controls on this page, as a result this page may not display as intended." Delete any such infected message and empty your email trash folder.
4. If you know who sent you the email, contact them and tell them that their system is infected by this worm.

Solution 2--How to remove this worm (mostly in MS-DOS mode)
Here is a list of steps to remove the worm. Detailed instructions follow:

• Start the computer in MS-DOS mode.
• Remove the worm entry from the Autoexec.bat file.
• Remove worm-infected files in MS-DOS mode.
• Remove the worm entry from the registry.
• Disable or uninstall the Windows Scripting host.
• Delete worm-infected files from Quarantine.
• Clear deleted items folder.
• Install the Microsoft patch.
• Take action after installing the Microsoft patch.

To start the computer in MS-DOS mode:

• If you are running Windows 95, follow these steps:
  1. If the computer is on, close all programs, and if possible, shut down Windows.
  2. Turn off the computer and wait thirty seconds. You must turn off the power to clear memory. Do not press the reset button.
  3. Restart the computer and watch the screen. When you see "Starting Windows 95," press F8.
  4. Select "Safe Mode Command Prompt Only" from the startup menu, and then press Enter.
• If you are using Windows 98, then follow these steps:
  1. If the computer is on, close all programs, and if possible, shut down Windows.
  2. Turn off the computer and wait thirty seconds. You must turn off the power to clear memory. Do not press the reset button.
  3. Restart the computer and immediately press and hold down the Ctrl key until the Windows 98 startup menu appears.
  4. Select "Safe Mode Command Prompt Only" from the startup menu, and then press Enter.

To remove the worm entry from the Autoexec.bat file:

1. At the DOS prompt, type edit autoexec.bat and then press Enter. The DOS editor opens.
2. Delete or remark out any lines with entries that refer to C:WindowsStart MenuProgramsStartUpdem.hta.
3. Press Alt+F, and then press S to save the file.
4. Press Alt+F, and then press X to exit the DOS editor.

To remove worm-infected files in MS-DOS mode:

NOTE: These instructions assume that the path to your Windows folder is C:Windows. If you installed Windows to a different folder, such as C:Win95, then modify the commands that refer to the Windows folder accordingly.

1. Type the following commands in the sequence shown. Press Enter after each one.
   cd windows
   attrib -s -h -r dem.htm
   del c:windowsdem.htm
   cd system
   attrib -s -h -r *.hta
   del *.hta
   cd..
   cd startm~1
   cd programs
   cd startup
   attrib -s -h -r dem.hta
   del dem.hta
2. Turn off the computer and wait at least 30 seconds. Do not press the reset button.
3. Restart the computer. When Windows starts, proceed to the next section.
   
   NOTE: If after restarting the computer, you see a blank <name>.hta screen opening at startup, repeat the previous steps.

To remove the worm entry from the registry:

CAUTION: We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to and click the following key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoft
   WindowsCurrentVersionRun
   
   NOTE: If you are running Windows 98, in addition to the Run key, perform the next step on the Run- key if it exists. (The Run- key will exist only if you have used the System Configuration Utility to disable programs loading from the registry.)
   
4. Look for the following String value in the right pane.
   
   Demoniacal "C:WINDOWSSYSTEM(name).hta"
   
5. If it exists, select it, press Delete, and then click Yes to confirm.
6. Navigate to and click the following key:
   
   HKEY_CURRENT_USERIdentities<Identity>
   SoftwareMicrosoftOutlook Express5.0Signatures
   
   NOTES:
   • The <Identity> key will be different on each computer. It is a long string of numbers and letters in brackets, similar to {2F3FF060-E5E4-11D3-B5CD-CC519BEAAC42}
   • If you have multiple accounts, then you may have more than one <Identity> key. If this is the case, then you must do this for each one.
   • Make sure that you go all of the way down through the keys and that you select the Signatures subkey. Do not delete the Identities key itself.
     
7. Press Delete, and then click Yes to confirm.
8. Exit the Registry editor.

To disable, uninstall, or block malicious scripts used by the Windows Scripting Host:
The Microsoft Windows Scripting Host enables you to run Visual Basic Scripting and JScript within Windows. Most programs do not use this scripting. Because several worms, including JS.KakWorm.G have made use of this scripting, you may want to take additional steps to prevent the spread of infection by worms that make use of it.

• If you are using Norton AntiVirus 2001, a free program update that includes Script Blocking is available. Please run LiveUpdate to obtain it.
• For other versions of Norton AntiVirus, SARC offers a tool to disable the Windows Scripting Host.

To delete infected files from Quarantine:
The files that were infected by JS.KakWorm.G are no longer necessary on your system. To permanently delete these infected files, see the document How to remove files from Norton AntiVirus Quarantine.

To clear the deleted items folder:
If you do not have Outlook Express set to clear deleted email messages when you close the program, then empty this folder before you send or receive email.

To install the Microsoft patch:
If you have not already done so, then install the Microsoft Scripting update, which is available at the following Internet address:
http://www.microsoft.com/TechNet/IE/tools/scrpteye.asp

For help with this, see the document How to download and install the Microsoft Scripting update.

What to do after installing the Microsoft patch
After you have removed the worm and installed the Microsoft security patch, do the following any time that NAV detects an email infected with the JS.KakWorm.G:

1. Note which specific email message is infected.
2. Click "Ignore the problem and continue with the infected file."
   
   NOTE: Any other action will disrupt the message index, and the downloaded messages will not be cleaned from the email server. The next time that you download mail, you will have all of the previous message including those infected with JS.KakWorm.G.
   
3. When you open or preview the infected message, you will see the message "An active X control on this page is not safe: Your current security settings prohibit running unsafe controls on this page, as a result this page may not display as intended." Delete any such infected message and empty your email trash folder.
4. If you know who sent you the message, contact them and tell them that their system is infected by this worm.