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Discovered: July 10, 2001
Updated: February 13, 2007 11:57:32 AM
Also Known As: W32.Malot.int, I-Worm.Petik [Kaspersky], W32/PetTick@MM [McAfee]
Type: Worm
Systems Affected: Windows

W32.Pet_Tick.G is a mass-mailing worm that:

  • Infects all the .html files in the \Windows folder
  • Sends country information, which it finds in the Win.ini file, to the attacker
  • Sends copies of the worm to mailto: address, which it finds in the cache folder of Internet Explorer
  • May also modify the Win.ini file

Virus definitions dated prior to July 13, 2001 detect this threat as W32.Malot.int.

Due to bugs, this worm:
  • May cause system instability or cause the system to stop responding when the worm is run.
  • Repeatedly infects files in the \Windows folder.

Antivirus Protection Dates

  • Initial Rapid Release version July 10, 2001
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version July 10, 2001
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date July 10, 2001

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Atli Gudmundsson

Discovered: July 10, 2001
Updated: February 13, 2007 11:57:32 AM
Also Known As: W32.Malot.int, I-Worm.Petik [Kaspersky], W32/PetTick@MM [McAfee]
Type: Worm
Systems Affected: Windows

Throughout this writeup:

  • \Windows refers to the folder in which Windows is installed, even if the folder has a name other than \Windows.
  • \Startup refers to the \Startup folder of the user who was logged on to Windows when the worm was executed.

1. Arrival
This worm arrives as the following email message:

Subject: New Virus Alert !!
This is a fix against I-Worm.Magistr.
Run the attached file (MSVA.EXE) to detect, repair and protect you against this malicious worm

The email message is designed to appear to be sent by Microsoft, when in fact it has been mailed by the worm.

2. Insertions
This worm inserts the following files on the computer:
  • \Windows\Runw32.exe
  • \Windows\System\Msva.exe
  • \Startup\VARegistered.htm

3. Modifications
The worm may add a line to the Win.ini file as follows:


4. Infections
A small script is appended to files with .htm* extensions that are in the \Windows folder. The script causes the following message to be displayed:

This file is infected by my new virus
Written by PetiK (c)2001

The worm also changes the Internet Explorer home page to the attacker's home page.

5. How the worm works
Activation from locations other than the \Windows folder
When the worm is executed, if it is not located in the \Windows folder, it does the following:
  • Inserts itself onto the system
  • Modifies the Win.ini file
  • Creates the VARegistered.htm file
  • Displays the following message:

Activation from the \Windows folder
When the worm is executed, if it is located in the \Windows folder, it does the following each time Windows starts (following the initial infection):
  • Infects all the .html files in the \Windows folder.
  • Sends country information it finds in the Win.ini file to the author, using a mail server located in the United Kingdom.
  • Iterates through the cache folder of Internet Explorer and searches for the .htm* files. Each file that is found is searched for lines that contain the mailto: command. The mailto: commands are used to send each recipient an email message that contains a copy of the worm.

6. Payload
On Tuesdays, the worm changes the title bar text of the System Properties window to PetiK always is with you :-).


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.

Writeup By: Atli Gudmundsson

Discovered: July 10, 2001
Updated: February 13, 2007 11:57:32 AM
Also Known As: W32.Malot.int, I-Worm.Petik [Kaspersky], W32/PetTick@MM [McAfee]
Type: Worm
Systems Affected: Windows

The following instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Disable System Restore (Windows Me/XP).
  2. Update the virus definitions.
  3. Run a full system scan and delete all the files detected as W32.Pet_Tick.G.

For specific details on each of these steps, read the following instructions.

1. Disabling System Restore (Windows Me/XP)
If you are running Windows Me or Windows XP, we recommend that you temporarily turn off System Restore. Windows Me/XP uses this feature, which is enabled by default, to restore the files on your computer in case they become damaged. If a virus, worm, or Trojan infects a computer, System Restore may back up the virus, worm, or Trojan on the computer.

Windows prevents outside programs, including antivirus programs, from modifying System Restore. Therefore, antivirus programs or tools cannot remove threats in the System Restore folder. As a result, System Restore has the potential of restoring an infected file on your computer, even after you have cleaned the infected files from all the other locations.

Also, a virus scan may detect a threat in the System Restore folder even though you have removed the threat.

For instructions on how to turn off System Restore, read your Windows documentation, or one of the following articles:

Note: When you are completely finished with the removal procedure and are satisfied that the threat has been removed, re-enable System Restore by following the instructions in the aforementioned documents.

For additional information, and an alternative to disabling Windows Me System Restore, see the Microsoft Knowledge Base article, "Antivirus Tools Cannot Clean Infected Files in the _Restore Folder ," Article ID: Q263455.

2. Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain virus definitions: These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate).
  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater).

    The Intelligent Updater virus definitions are available: Read "How to update virus definition files using the Intelligent Updater" for detailed instructions.

3. Scanning for and deleting the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected as infected with W32.Pet_Tick.G, click Delete.

Writeup By: Atli Gudmundsson