Discovered: October 31, 2003
Updated: February 13, 2007 12:13:07 PM
Also Known As: W32/Mimail.c@mm [McAfee], WORM_MIMAIL.C [Trend], W32/Mimail-C [Sophos], I-Worm.Mimail.c [Kaspersky], Win32.Mimail.C [Computer Assoc
Type: Worm
Systems Affected: Windows


Due to a decreased rate of submissions, Symantec Security Response has downgraded W32.Mimail.C@mm to a Category 2 threat from a Category 3 threat as of November 13, 2003.

W32.Mimail.C@mm is a variant of W32.Mimail.A@mm that spreads by email and steals information from infected computers.

The email has the following characteristics:

Subject: Re[2]: our private photos [random string of letters]
Attachment: photos.zip



Antivirus Protection Dates

  • Initial Rapid Release version October 31, 2003
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version October 31, 2003
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date October 31, 2003

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

Writeup By: Benjamin Nahorney

Discovered: October 31, 2003
Updated: February 13, 2007 12:13:07 PM
Also Known As: W32/Mimail.c@mm [McAfee], WORM_MIMAIL.C [Trend], W32/Mimail-C [Sophos], I-Worm.Mimail.c [Kaspersky], Win32.Mimail.C [Computer Assoc
Type: Worm
Systems Affected: Windows


When W32.Mimail.C@mm is executed, it does the following:

  1. Copies itself as %Windir%\Netwatch.exe.


    Notes:
    • On Windows 95/98/Me, Netwatch.exe is a legitimate file, 72kb in size. The worm will overwrite this file, replacing it with an infected file 13kb in size.
    • %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:\Windows or C:\Winnt) and copies itself to that location.

  2. Adds the value:

    "NetWatch32" = "%Windir%\netwatch.exe"

    to the registry key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

  3. Collects email address from all the files on the computer, except those with the extensions:
    • com
    • wav
    • cab
    • pdf
    • rar
    • zip
    • tif
    • psd
    • ocx
    • vxd
    • mp3
    • mpg
    • avi
    • dll
    • exe
    • gif
    • jpg
    • bmp

  4. Writes all the email addresses to the file, %Windir%\eml.tmp.

  5. Checks to see whether there is a valid Internet connection by attempting to connect to www.google.com.

  6. Captures text from specific windows and sends the data to predetermined email addresses.

  7. Sends email messages using its own SMTP engine. For each email address the worm gathers, it will:
    1. Look up the Mail Exchange (MX) record for the domain name using the DNS server of the current host. If a DNS server is not found, it will default to 212.5.86.163.
    2. Acquire the mail server associated with that particular domain.
    3. Directly contact the destination server.

      The email has the following characteristics:

      From: james@<recepient domain> (The from address may be spoofed to appear that it is coming from the recipient domain)

      Subject: Re[2]: our private photos [random sequence of letters]

      Message:
      Hello Dear!,

      Finally i've found possibility to right u, my lovely girl :)
      All our photos which i've made at the beach (even when u're without ur bh:))
      photos are great! This evening i'll come and we'll make the best SEX :)
      Right now enjoy the photos.

      Kiss, James.
      [random sequence of letters]

      Attachment: photos.zip


      Note: Photos.zip contains only one file, photos.jpg.exe.

  8. Performs a Denial of Service (DoS) with the following characteristics:
    • Randomly selects a site from the names below:

      a. darkprofits.net
      b. www.darkprofits.net
      c. darkprofits.com
      d. www.darkprofits.com

    • The DoS routine is designed to have 15 attacking threads active at any moment.
    • Each thread performs one TCP connection or an ICMP attack, and then sleeps for five seconds.
    • Randomly chooses to perform a TCP connection on port 80 or to perform an ICMP attack.
    • The packets sent to the victim carry a 2k payload filled with random data.
    • Uses a random ICMP type when performing the ICMP attack.
    • The data sent is either the GET request or some random data when performing the HTTP connection.

  9. Creates two additional files in the %Windir% folder:
    • Zip.tmp: A temporary copy of message.zip (12,958 bytes).
    • Exe.tmp: A temporary copy of message.html (12,832 bytes).

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: Benjamin Nahorney

Discovered: October 31, 2003
Updated: February 13, 2007 12:13:07 PM
Also Known As: W32/Mimail.c@mm [McAfee], WORM_MIMAIL.C [Trend], W32/Mimail-C [Sophos], I-Worm.Mimail.c [Kaspersky], Win32.Mimail.C [Computer Assoc
Type: Worm
Systems Affected: Windows



Removal using the W32.Mimail Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Mimail.C@mm. This is the easiest way to remove this threat and should be tried first.

Manual Removal
As an alternative to using the removal tool, you can manually remove this threat.

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.Mimail.C@mm.
  4. Delete the value that was added to the registry.
  5. Restore the Netwatch.exe file (Windows 95/98/Me).
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.Mimail.C@mm, click Delete.

4. Deleting the value from the registry


WARNING: Symantec strongly recommends that you back up the registry before making any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
  1. Click Start, and then click Run. (The Run dialog box appears.)
  2. Type regedit

    Then click OK. (The Registry Editor opens.)

  3. Navigate to the key:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

  4. In the right pane, delete the value:

    "NetWatch32" = "%Windir%\netwatch.exe"

  5. Exit the Registry Editor.

5. Restoring the Netwatch.exe file (Windows 95/98/Me only)
If the worm overwrote the original Netwatch.exe file, re-install this file. Refer to the following information for details.


Note: The instructions in this document are provided for your convenience. The extraction of Windows files uses Microsoft programs and commands. Symantec does not provide warranty support for or assistance with Microsoft products. If you have any questions, refer to your Windows documentation or contact Microsoft.

Windows Me
If you are running Windows Me, you can restore the file using the System Configuration Utility.
  1. Click Start, and then click Run.
  2. Type msconfig, and then press Enter.
  3. Click Extract Files. (The "Extract one file from installation disk" dialog box appears.)
  4. In the "Specify the system file you would like to restore" box, type the following:

    c:\windows\netwatch.exe

    Then click Start.

    NOTE: If you installed Windows to a different location, make the appropriate path substitution.

    (The Extract File dialog box appears.)

  5. Next to the "Restore from" box, click Browse, and then browse to the location of the Windows installation files. If they were copied to the hard drive, this is, by default, C:\Windows\Options\Install. You can also insert the Windows installation CD into the CD-ROM drive and browse to that location.
  6. Click OK, and then follow the prompts.


Windows 98
If you are using Windows Me, you can restore the file using the System File Checker.
  1. Click Start, and then click Run.
  2. Type sfc, and then press Enter.
  3. Click "Extract one file from installation disk."
  4. In the "Specify the system file you would like to restore" box, type the following:

    c:\windows\netwatch.exe

    and then click Start.

    NOTE: If you installed Windows to a different location, make the appropriate path substitution.

    (The Extract File dialog box appears.)

  5. Next to the "Restore from" box, click Browse, and then browse to the location of the Windows installation files. If they were copied to the hard drive, this is, by default, C:\Windows\Options\Cabs. You can also insert the Windows installation CD into the CD-ROM drive and browse to that location.
  6. Click OK, and then follow the prompts.

Windows 95 (or an alternative method for Windows 98/Me)
If you are running Windows 95, use the Extract command. You can also use this on Windows 98/Me.
  1. Click Start, point to Find or Search, and then click Files or Folders.
  2. Make sure that "Look in" is set to (C:) and that Include subfolders is checked.
  3. In the "Named" or "Search for..." box, type: precopy1
  4. Click Find Now or Search Now. If it does not exist on the hard disk, then insert the Windows installation CD and repeat the search on that particular drive.
  5. When you find the file, write down the location of Precopy1; for example, C:\Windows\Options\Cabs. This is your Source Path.
  6. The general form of the Extract command is:

    extract <Source Path>\precopy1.cab netwatch.exe /L c:\windows

    So, if the source path is C:\Windows\Options\Cabs, then the Extract command becomes:

    extract c:\windows\options\cabs\precopy1.cab netwatch.exe /L c:\windows


    Note: If you installed Windows to a different location, make the appropriate path substitution.

  7. Click Start, and then click Run.
  8. Type the following:

    extract <Source Path>\precopy1.cab netwatch.exe /L c:\windows

    making the appropriate path substitutions as aforementioned.

  9. Click OK.

For more information on how to use the Microsoft Extract command, see the Microsoft Knowledge Base document, "How to Extract Original Compressed Windows Files ," Article ID: Q129605.


Writeup By: Benjamin Nahorney