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Discovered: March 30, 2005
Updated: February 13, 2007 12:36:01 PM
Type: Trojan Horse
Systems Affected: Windows

Trojan.Littlog is a Trojan horse that installs a keylogger and uploads the log to a predetermined FTP server.

Antivirus Protection Dates

  • Initial Rapid Release version March 30, 2005
  • Latest Rapid Release version May 07, 2019 revision 006
  • Initial Daily Certified version March 30, 2005
  • Latest Daily Certified version May 07, 2019 revision 008
  • Initial Weekly Certified release date March 30, 2005

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

Technical Description

When Trojan.Littlog is executed, it performs the following actions:

  1. Copies itself as one or more of the following:

    • %System%\fontstyles.exe
    • %Windir%\4DFlowerBox.scr
    • %Windir%\mseiw.exe
    • %Windir%\mssiex.exe

    • %System% is a variable that refers to the System folder. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (WindowsNT/2000), or C:\Windows\System32 (Windows XP).
    • %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows or C:\Winnt.

  2. Drops the following files:

    • [original folder]\settings.ini
    • [original folder]\server.exe

  3. Creates any of the following directories:

    • %System%\webdav
    • %System%\wednav

  4. Adds any of the following values:

    "msiew" = "%Windir%\mseiw.exe"
    "mssiex" = "%Windir%\mssiex.exe"

    to the registry subkeys:


    so that Trojan.Littlog runs every time Windows starts.

  5. Drops any of the following dll files:

    • %Windir%\syxsocks.dll
    • %Windir%\mssiex.dll

  6. Adds any of the following values:

    "mseiw" = "[path to original file]"
    "mssiex" = "[path to original file]"

    to the registry subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings

  7. Adds the values:

    "Shell" = "explorer.exe 4DFlowerBox.scr"
    "System" = "C:\WINNT\System32\fontstyles.exe"

    to the registry subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

  8. Adds any of the following values:

    "load" = "mseiw"
    "run" = "mseiw"
    "load" = "mssiex.exe"
    "run" = "mssiex.exe"

    to the registry subkey:

    HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows

  9. Injects the dropped dll file into the Internet Explorer process. The process is running with hidden mode so that the user cannot see the Internet Explorer window.

  10. Starts to log keystrokes and saves them to %Windir%\cht.pol.

  11. Uploads the log file to a predetermined FTP server.

  12. Sends the IP address of the compromised computer to a predetermined Web server.


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.


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 Trojan.Littlog.
  4. Delete any values added to the registry.
For specific details on each of these steps, read the following instructions.

1. To disable 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:
When you are completely finished with the removal procedure and are satisfied that the threat has been removed, reenable 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. To update 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 document: Virus Definitions (LiveUpdate).
  • Downloading the definitions using the Intelligent Updater: The Intelligent Updater virus definitions are posted daily. 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 document: Virus Definitions (Intelligent Updater).

    The latest Intelligent Updater virus definitions can be obtained here: Intelligent Updater virus definitions. For detailed instructions read the document: How to update virus definition files using the Intelligent Updater.

3. To scan for and delete 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 Trojan.Littlog, click Delete.

    If your Symantec antivirus product reports that it cannot delete an infected file, Windows may be using the file. To fix this, run the scan in Safe mode. For instructions, read the document: How to start the computer in Safe Mode. Once you have restarted in Safe mode, run the scan again.

    After the files are deleted, restart the computer in Normal mode and proceed with section 4.

4. To delete the value from the registry
Important: 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 subkeys only. For instructions refer to the document: How to make a backup of the Windows registry.
  1. Click Start > Run.
  2. Type regedit
  3. Click OK.

  4. Navigate to the subkeys:


  5. In the right pane, delete the value with any of the following names:

    "msiew" = "%Windir%\mseiw.exe"
    "mssiex" = "%Windir%\mssiex.exe"

  6. Navigate to the subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Internet Settings

  7. In the right pane, delete the value with any of the following names:

    "mseiw" = "[path to original file]"
    "mssiex" = "[path to original file]"

  8. Navigate to the subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon

  9. In the right pane, delete the values:

    "Shell" = "explorer.exe 4DFlowerBox.scr"
    "System" = "C:\WINNT\System32\fontstyles.exe"

  10. Navigate to the subkey:

    HKEY_CURRENT_USER\Software\Microsoft\Windows NT\CurrentVersion\Windows

  11. In the right pane, delete the values with any of the following names:

    "load" = "mseiw"
    "run" = "mseiw"
    "load" = "mssiex.exe"
    "run" = "mssiex.exe"

  12. Exit the Registry Editor.

Writeup By: Kaoru Hayashi