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SARC Write-up - Wscript.KakWorm.htm mario dragunsky



Title: SARC Write-up - Wscript.KakWorm
Bonjour André et tous les amis de Quéâtre,
 
Voilà des infos très complètes sur le virus transmis malhencontreusement par la liste. Celui-ci ne se transmet qu'à ceux qui ont la version non patché (si je peux m'exprimer ainsi) d'Outlook Express comme expliqué (en anglais) ci dessous.
J'espère que grâce à ce message ceux qui sont infectés pourront vite guérir!
Toutes les réponses à vos questions sont dans ce (long) texte!
 
Amitiés
 
Mario Dragunsky
http://www.les4cats.com
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Level 4

Wscript.KakWorm

Discovered on: December 30, 1999

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VBS.KakWorm spreads using Microsoft Outlook Express. It attaches itself to all outgoing messages using the Signature feature of Outlook Express and Internet Explorer newsgroup reader.
The worm utilizes a known Microsoft Outlook Express security hole so that a viral file is created on the system without having to run any attachment. Simply reading the received email message causes the virus to be placed on the system.
Microsoft has patched this security hole. The patch is available at:

http://www.microsoft.com/technet/ie/tools/scrpteye.asp

If you have a patched version of Outlook Express, this worm will not work automatically.
Click here to download a tool to repair Wscript.Kakworm damage.

NOTES:

  • This document contains information about the Wscript.KakWorm. There are differences between Wscript.KakWorm and the next major variant of this worm, Wscript.KakWorm.B (note the "B"). The removal procedures are different.
  • Although this worm can be forwarded or detected in email on a Windows NT system, it infects only Windows 95/98 systems.
  • If Norton AntiVirus has detected the Wscript.KakWorm and you cannot download email, then see the document Cannot download email after you delete or quarantine an email message infected with the Wscript.KakWorm.
  • While computers running either unpatched Microsoft Outlook or Outlook Express can be infected, only Outlook Express can automatically spread the infection.
  • One indication of this worm--though it does not occur on all systems--is the message "Driver or memory error" that appears briefly as Windows starts.

Also Known As: : VBS.Kak.Worm, VBS.Kak.Worm.dr, Kagou-Anti-Krosoft

Category: Worm

Infection Length: 4116 Bytes

Virus Definitions: December 30, 1999

Threat Assessment:

High Medium High
Wild:
High
Damage:
Medium
Distribution:
High

Wild:

Damage:

Distribution:

Technical description:

Wscript.KakWorm is a worm. It spreads using Microsoft Outlook Express. The worm attaches itself to all outgoing messages using the Signature feature of Outlook Express. Signatures enable you to automatically append information at the end of all outgoing messages.

This worm uses three files to deliver its payload. The file extensions are:

  • .hta
  • .reg
  • .bat

The message that contains this worm is written in an HTML format that supports scripting. It uses a security hole in Microsoft Outlook/Outlook Express that is known as "Scriptlet TypeLib," and it places a shortcut to an .hta file in the StartUp folder. The next time the computer is restarted, the .hta file is run.

NOTE: While computers running either unpatched Microsoft Outlook or Outlook Express can be infected, only Outlook Express can automatically spread the infection.

This worm can reinfect your computer if it is displayed in the preview pane of Outlook Express. This can happen when switching between folders. (This means that a viral file can be created on the system without having to open an attachment.) This can be prevented by applying Microsoft's security update patch. With this update, you are asked whether you want to run the ActiveX control which is marked "safe for scripting."

If you have a patched version of Outlook Express, then this worm will not affect you. To obtain the Microsoft patch, go to http://www.microsoft.com/TechNet/IE/tools/scrpteye.asp. Additional information is available at this location. Most users will want to download the Intel version.

If a system is infected, then there will be no real indication of this until the first day of any given month. On the first of the month you will see the following message:

"Kagou-Anti-Kro$oft says not today!"

If you click OK, the computer shuts down. This window returns each time you start Windows.

NOTE: As noted previously, Wscript.KakWorm is spread as part of an email message--not an attachment. If, however, your email program or the email server that handles the message is not set up for or capable of handling HTML encoded messages, the program or server will convert the encoded message to an attachment. This attachment usually has a name such as Att1.htm. If you open the attachment, it can have the same effect as if you received the email message with the worm embedded.

Removal instructions:

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. The tool is available at the following Internet address:

    http://service1.symantec.com/sarc/sarc.nsf/html/Wscript.Kakworm.Fix.html
  • 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 computer consultant.

Solution 1 -- To remove this worm from within Windows, follow these instructions:
  • Restart the computer in Safe Mode.
  • Enable show all files.
  • Find and delete the kak.*, *.kak, 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.
  • 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 using 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 use 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 using Windows 98, then 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 then 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 use 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:
    1. Double-click the My Computer icon on the Windows desktop.
    2. Click View, and click Options or Folder options.
    3. Click the View tab, and uncheck "Hide file extensions for known file types."
    4. Click Show all files, 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 kak.* in the Named box, and then click Find Now.
    4. In the results pane, select each file that is found, 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 *.kak 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 your 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:\Windows\Start Menu\Programs\StartUp\kak.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 kak--then it should be deleted.

    @echo off C:\Windows\Start Menu\Programs\StartUp\kak.hta
    Del C:\Windows\Start Menu\Programs\StartUp\kak.hta


    5. Because some variants hide the kak entry elsewhere in the Autoexec.bat file, search the file to make sure that no entries have been missed:
      a. Make sure that the cursor is positioned at the beginning of the Autoexec.bat file.
      b. Click Search, and click Find.
      c. Type kak in the Find box, and then click Next.
      • If you see the message, "Cannot find 'kak'," then proceed to the next step.
      • If an entry is found that contains kak, delete it, and then press the F3 key to repeat the search. Keep repeating the search until all references to kak have been removed and you see the message "Cannot find kak." 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_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    NOTE: If you are using 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.

    cAg0u "C:\WINDOWS\SYSTEM\(name).hta"

    5. If it exists, click it, press Delete, and then click Yes to confirm.
    6. Navigate to and click the following subkey:

    HKeyCurrentUser\Identities\<Identity>\Software\Microsoft\Outlook Express\5.0\Signatures

    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 the Registry Editor, and then restart your 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 or uninstall 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 Wscript.KakWorm have made use of this scripting, which is similar to a macro, you may want to remove it if it is not needed; this will prevent the spread of infection by worms that make use of it. Please see the document How to disable or remove the Windows Scripting Host for detailed instructions.

To delete worm-infected files from Quarantine:
The files that were infected by Wscript.KakWorm 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 the Wscript.KakWorm:
    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 Wscript.KakWorm.

    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--To remove this worm (mostly in MS-DOS mode) follow these instructions:
  • 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 using Windows 95, then follow these steps:
      1. If the computer is on, close all programs, and then, 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 then, 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:\Windows\Start Menu\Programs\StartUp\kak.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 kak.htm
    del c:\windows\kak.htm
    cd system
    attrib -s -h -r *.hta
    del *.hta
    cd..
    cd startm~1
    cd programs
    cd startup
    attrib -s -h -r kak.hta
    del kak.hta

    2. Turn off the computer and wait at least 30 seconds. Do not use 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_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

    NOTE: If you are using 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.

    cAg0u "C:\WINDOWS\SYSTEM\(name).hta"

    5. If it exists, select it, press Delete, and then click Yes to confirm.
    6. Navigate to and click the following subkey:

    HKeyCurrentUser\Identities\<Identity>\Software\Microsoft\Outlook Express\5.0\Signatures

    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 or uninstall 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 Wscript.KakWorm have made use of this scripting, which is similar to a macro, you may want to remove it if it is not needed; this will prevent the spread of infection by worms that make use of it. Please see the document How to disable or remove the Windows Scripting Host for detailed instructions.

To delete infected files from Quarantine:
The files that were infected by Wscript.KakWorm 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 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 Wscript.KakWorm:
    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 Wscript.KakWorm.

    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.


Write-up by: Eric Chien

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