W32.Alco.AB@mm

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Discovered: March 11, 2003
Updated: February 13, 2007 11:44:10 AM
Type: Worm
Systems Affected: Windows


W32.Alco.AB@mm is a mass-mailing worm that sends itself to all the email addresses that it finds in the .htm and .html files. The email has the following characteristics:

From : Chief Skaler <admin@evol.com>
Subject: Evol Worm
Message:
There was an error with your smtp provider please read the datalink and send a copy to your ISP. Error1106 : Dead datalink (report is attatched).
Attachment: Errorlog.exe

The worm copies itself to the default shared folders of the KaZaA, Bearshare, and eDonkey2000 file-sharing networks. The worm also attempts to spread through IRC.

This threat is written in the Microsoft Visual Basic programming language.

Antivirus Protection Dates

  • Initial Rapid Release version March 12, 2003
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version March 12, 2003
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date March 12, 2003

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

Writeup By: Yana Liu

Discovered: March 11, 2003
Updated: February 13, 2007 11:44:10 AM
Type: Worm
Systems Affected: Windows


When W32.Alco.AB@mm runs, it does the following:

  1. Copies itself as:
    • C:\Windows\Taskman.exe
    • C:\Windows\Notepad.exe
    • C:\Windows\Wjview.exe
    • C:\Windows\Errorlog.exe
    • C:\Windows\System\_.dat, whose attributes are set to read_only and hidden.
    • C:\Windows\System\Errorlog.exe
    • C:\Windows\System32\Errorlog.exe
    • C:\Win\errorlog.exe
    • C:\Program Files\Evol.exe
    • C:\Program Files\Msn.exe
    • C:\Program Files\Uninstall.exe
    • C:\Program Files\Kazaa\My shared folder\Unreal 2003 no cd patch.exe
    • C:\Program Files\Kazaa\My shared folder\Unreal no cd patch.exe
    • C:\Program Files\Bearshare\shared\Unreal 2003 no cd patch.exe
    • C:\Program Files\Bearshare\shared\Unreal no cd patch.exe
    • C:\Program Files\eDonkey2000\Incoming\Unreal 2003 no cd patch.exe
    • C:\Program Files\eDonkey2000\Incoming\Unreal no cd patch.exe
    • C:\INETPUB\Wwwroot\Evol.exe
    • A:\AutoExec.exe

  2. Creates the text file, C:\T.txt.
  3. Attempts to modify the (Default) value of the registry key:

    HKEY_CLASSES_ROOT\exefile\shell\open\command

    to:

    C:\Program Files\msn.exe

    so that the worm runs each time you run a .exe file.
  4. Creates the following files:
    • C:\INETPUB\WWWROOT\Default.htm
    • C:\INETPUB\WWWROOT\Index.htm
    • C:\INETPUB\WWWROOT\Index.html
  5. Creates or overwrites the Script.ini file in one of the following folders:
    • C:\Program Files\mIRC
    • C:\Program Files\mIRC32
    • C:\mIRC
    • C:\mIRC32

      The worm uses script.ini to send a copy of itself to other mIRC users who connect to the same channel as the infected computer.

  6. Opens a randomly chosen TCP port.
  7. Sends itself to all the email addresses that it finds in the .htm and .html files. The email has the following characteristics:

    From: Chief Skaler <admin@evol.com>
    Subject: Evol Worm
    Message:
    There was an error with your smtp provider please read the datalink and send a copy to your ISP. Error1106 : Dead datalink (report is attatched).
    Attachment: Errorlog.exe


Recommendations

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: Yana Liu

Discovered: March 11, 2003
Updated: February 13, 2007 11:44:10 AM
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. Update the virus definitions.
  2. Run a full system scan and delete all the files detected as W32.Alco.AB@mm.
  3. Copy Regedit.exe to Regedit.com and edit the registry

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


NOTES:
  • If the worm has not yet run—that is, the worm's file was copied to your computer but has not run—you should be able to follow the instructions in sections 1 and 2, which discuss detecting and removing this file. (If the worm has run, in some cases you will not be able to perform these steps, because the modifications that the worm made will prevent you from doing so.)
  • If the worm has run and you cannot run the .exe files, first follow the instructions in section 3. After you complete those instructions, follow sections 1 and 2.


1. 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 here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

2. 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.Alco.AB@mm, click Delete.


3. Copying Regedit.exe to Regedit.com and editing the registry
Because the worm may have modified the registry so that you cannot run .exe files, first make a copy of the Registry Editor as a file with the .com extension, and then run the file.
  1. Do one of the following, depending on the version of Windows you are running:
    • Windows 95/98 users:
      1. Click Start.
      2. Point to Programs.
      3. Click the MS-DOS Prompt. (A DOS window opens at the C:\Windows prompt.) Proceed to step B of this section.
    • Windows Me users:
      1. Click Start.
      2. Point to Programs.
      3. Point to Accessories.
      4. Click the MS-DOS Prompt. (A DOS window opens at the C:\Windows prompt.) Proceed to step B of this section.
    • Windows NT/2000 users:
      1. Click Start, and then click Run.
      2. Type command, and then press Enter. (A DOS window opens.)
      3. Type cd \winnt, and then press Enter.
      4. Go to step B of this section.
    • Windows XP users:
      1. Click Start, and then click Run.
      2. Type command, and then press Enter. (A DOS window opens.)
      3. Type the following:

        cd\
        cd \windows

        Press Enter after typing each one.
      4. Proceed to step 2 of this section.

  2. Type copy regedit.exe regedit.com

    And then press Enter.
  3. Type start regedit.com

    And then press Enter. (The Registry Editor opens in front of the DOS window.)

    After you finish editing the registry, exit the Registry Editor, and then exit the DOS window as well.
  4. Before continuing, 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 the specified keys only. For instructions, read the document, "How to make a backup of the Windows registry."
  5. Navigate to and select the key:

    HKEY_LOCAL_MACHINE\Software\Classes\exefile\shell\open\command

    NOTE: The HKEY_LOCAL_MACHINE\Software\Classes key contains many subkey entries that refer to other file extensions. One of these file extensions is .exe. Changing this extension can prevent any files ending with a .exe extension from running. Make sure that you completely browse through this path until you reach the \command subkey.

    Modify the HKEY_LOCAL_MACHINE\Software\Classes\exefile\shell\open\command subkey, shown in the following figure:

    <<=== NOTE: Modify this key.
  6. In the right pane, double-click the (Default) value.
  7. Delete the current value data, and then type:

    "%1" %*

    (That is, type the characters: quote-percent-one-quote-space-percent-asterisk).

    NOTES
    • Under Windows 95/98/Me/NT, the Registry Editor automatically encloses the value within quotation marks. When you click OK, the (Default) value should look exactly like this:

      ""%1" %*"  
    • Under Windows 2000/XP, the additional quotation marks will not appear. When you click OK, the (Default) value should look exactly like this:

      "%1" %*
    • Make sure that you completely delete all the value data in the command key before typing the correct data. If you leave a space at the beginning of the entry, any attempt to run the program files will result in the error message, "Windows cannot find .exe." If this occurs, restart the entire process from the beginning of this document and make sure that you completely remove the current value data.

  8. Exit the Registry Editor.



Writeup By: Yana Liu