Threat Explorer

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25 April 2001
13 February 2007
Also Known As:
VBS.Ketip.A@mm, VBS.Ketip.B@mm

VBS.Pet_Tick.A@mm is a Visual Basic Script (VBS) worm. It arrives as an HTML email message. Like many other worms, it uses Microsoft Outlook and IRC clients to spread. The script attempts to send information that is stolen from infected computers to some email addresses.

Antivirus Protection Dates

  • Initial Rapid Release version 25 April 2001
  • Latest Rapid Release version 28 September 2010 revision 054
  • Initial Daily Certified version 25 April 2001
  • Latest Daily Certified version 28 September 2010 revision 036
  • Initial Weekly Certified release date pending
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

When the worm is executed, it does the following:
  1. It copies itself to C:\Windows\Petik.txt.vbs.
  2. It adds the value

    Petik       <Windows System Folder>\Petik.txt.vbs

    to the registry key


    to enable itself to run at startup.
  3. It sends an HTML email message to all contacts in all Microsoft Outlook address lists. The email message is as follows:

    Subject: Important Message From Microsoft Corporation
    Message: "This message has permanent errors. <br>Sorry<br>"

    The HTML message contains Visual Basic Script, and it attempts to drop the file C:\Windows\Worm.vbs, but it fails to do so because of bugs in the worm's code.
  4. The worm then attempts to send the following information from the infected computer to and

    Infected Date
    Infected Time
    Computer Name
    OS Version
    OS Version Number
    Product ID
    Product Key
    Internet Explorer Start Page
    Internet Explorer Download directory path
    Windows directory path
    System directory path
    Temporary directory path
    Program Files directory path
  5. It next drops two .ini files for IRC clients:

    C:\Program Files\Pirch\Script.ini

    These do not work properly due to bugs in the worm's code.
  6. It modifies or overwrites following files:
    • Files with the extensions .vbs, .vbe, .js, and .jse are overwritten by the worm.
    • Files with the extensions .exe, .ini, .gif, .jpg, and .htm have the .vbs extension appended to them and are overwritten by the worm.
    • Files with the extensions .mp3, .doc, .xls, .ppt, and .hlp have their attribute set to hidden.

    If this process is executed, you will have to reinstall Windows and most programs because .exe files have been overwritten.


Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • 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.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a 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.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. 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.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

To remove this worm, delete files detected as VBS.Pet_Tick.A@mm, VBS.Pet_Tick.A@mm (2), or VBS.Pet_Tick.A@mm.ini, and undo the change the worm made to the registry.

To remove the worm:
  1. Run LiveUpdate to make sure that you have the most recent virus definitions.
  2. Start Norton AntiVirus (NAV), and run a full system scan, making sure that NAV is set to scan all files.
  3. Delete any files detected as VBS.Pet_Tick.A@mm, VBS.Pet_Tick.A@mm (2), or VBS.Pet_Tick.A@mm.ini.

To edit 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 the key

  4. In the right pane, delete the value

    Petik       <Windows System Folder>\Petik.txt.vbs
  5. Exit Registry Editor.

Writeup By: Kaoru Hayashi