W32.Femot.D.Worm

SUMMARY

The W32.Femot.D.Worm worm:

• Is a network-aware
• Has backdoor capabilities
• Is compressed with ASPack

The existence of the file Lasvr32.exe is an indication of a possible infection.

Protection

• Virus Definitions (LiveUpdate™ Weekly) July 16, 2003
• Virus Definitions (Intelligent Updater) July 14, 2003

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Medium
• Compromises Security Settings: Allows unathorized remote access to a compromised machine.

Distribution

• Distribution Level: Medium
• Ports: 135, 139, 1080, 8080
• Shared Drives: Attempts to copy itself to the IPC$ and Admin$ shares.

TECHNICAL DETAILS

When W32.Femot.D.Worm runs, it does the following:

1. Copies itself as %Windir%System32Lasvr32.exe.
   
   NOTE: %Windir% is a variable. The worm locates the Windows installation folder (by default, this is C:Windows or C:Winnt) and copies itself to the System32 subfolder under that location.
   
   
2. Creates the following files:
   • %Windir%System32Lasvr32.dll (45,056 bytes)
   • %Windir%System32MoFei.cfg.
     
     
3. On Windows 2000/NT/XP, it adds the service, "Smart Card Helper," and sets it to run the %Windir%System32Lasvr32.exe file.
   
   The Smart Card Helper service is installed on some version of Windows by default. If it is already installed, the worm attempts to replace the service with itself.
   
   
4. On Windows 2000/NT/XP, it injects its code to the LSASS.EXE and IEXPLORE.EXE processes.
   
   
5. On Windows 95/98/Me, it adds the value:
   
   "NavAgent32"="%Windir%System32lasvr32.exe" -v
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   so that the worm runs when you start Windows.
   
   
6. On Windows 95/98/Me, it also creates the following files:
   • %Windir%System32Navpw32.exe (15,360 bytes), which is the backdoor component of the worm.
   • %Windir%System32MoFei.id.
   • %Windir%System32MoFei.mis.
     
     Then the worm runs Navpw32.exe as a service.
     
     
7. Connects to the following Web sites by TCP port 8080 or 1080:
   • google.ods.org
   • windowsupdate.daemon.sh
     
     

Worm routine on Windows NT/2000/XP
The worm routine works only on Windows NT/2000/XP. The worm attempts to connect to other computers as either the current user or as Administrator.
It uses the following passwords:

• stgzs
• security
• super
• oracle
• secret
• root
• admin
• password
• passwd
• pass
• 88888888
• 888888
• 00000000
• 000000
• 11111111
• 111111
• 111
• fan@ing*
• 54321
• 654321
• 12345678
• 1234567
• 123456
• 12345
• 1234
• 123
• 12
  
  

If the worm successfully connects, it checks for the existence of the following files:

• %sADMIN$System32lasvr32.exe
• %sADMIN$System32MoFei.ver
  
  

If the files are not on the computer, it attempts to create the following files:

• %sADMIN$System32lasvr32.exe
• %sADMIN$System32MoFei.ver
• %sIPC$System32lasvr32.exe
• %sIPC$System32MoFei.ver

Then the worm adds and starts the service.

Backdoor
The worm listens for the commands from its creator, who may perform any of the following actions:

• Access the Windows command shell (Cmd.exe or Command.com)
• Run executable files
• Delete/create files and folders
• Download files from the Internet

Recommendations

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

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

REMOVAL

Removal using the W32.Femot.D.Worm Removal Tool
Symantec Security Response has created a tool to remove W32.Femot.D.Worm, which is the easiest way to remove this threat.

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. Finding and stopping the service.
4. Run a full system scan and delete all the files detected as W32.Femot.D.Worm. Delete MoFei.ver or MoFei.cfg if they exist.
5. Delete the values that were added to the registry.

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:

• "How to disable or enable Windows Me System Restore"
• "How to turn off or turn on Windows XP System Restore"

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. Finding and stopping the service

1. Click Start, and then click Run.
2. Type services.msc, and then click OK.
3. Locate and select the service, "Smart Card Helper."
4. Click Action, and then click Properties.
5. Click Stop, if applicable.
6. Change Startup Type to Manual.
7. Click OK and close the Services window.
8. Restart the computer.

4. 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.
   • For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
   • For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec Corporate antivirus product is set to scan all files."
2. Run a full system scan.
3. If any files are detected as infected with W32.Femot.D.Worm, click Delete.
4. Using Windows Explorer, look for the files, %Windir%System32Mofei.cfg and %sADMIN$System32MoFei.ver. Delete them if found.

5. Deleting the values from the registry

CAUTION: 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. On Windows 95/98/ME, navigate to the key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
4. In the right pane, delete the value:
   
   "NavAgent32"="%Windows%System32lasvr32.exe -v"
   
   
5. On Windows NT/2000/XP, navigate to the key:
   
   HKEY_LOCAL_MACHINESystemCurrentControlSetServicesSCardDrv
   
   
6. In the right pane, set the value: ImagePath
   
   to:
   
   %SystemRoot%System32SCardSvr.exe
   
   
7. Exit the Registry Editor.