Trojan.Noupdate.B

SUMMARY

Trojan.Noupdate.B is a Trojan horse that attempts to prevent users from updating their computer with the latest Microsoft Windows patches and antivirus updates.

Protection

• Virus Definitions (LiveUpdate™ Weekly) March 31, 2004
• Virus Definitions (Intelligent Updater) March 25, 2004

Threat Assessment

Wild

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

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

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

1. Registers its process as a service so that the Trojan will run, even if the user is logged off.
   
   
2. Adds the value:
   
   "reg32" = "%windir%eg32.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   
3. Modifies the values:
   
   • "Start Page" = "http:/ /allsearcher.info/"
   • "Local Page" = "http:/ /allsearcher.info/"
   • "Default_Page_URL" = "http:/ /allsearcher.info/"
     
     in the registry keys:
     
   • HKEY_LOCAL_MACHINESoftwareMicrosoftInternet ExplorerMain
   • HKEY_CURRENT_USERSoftwareMicrosoftInternet ExplorerMain
     
     
4. Deletes the values:
   
   • Key2
   • ControlPanel
     
     from the registry key:
     
     HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
     
     
5. Overwrites the following files with zero-byte files:
   
   • %Windows%hosts
   • c:system32driversetchosts
     
     
6. Closes windows that contain the Window name:
   
   System - Microsoft Internet Explorer
   
   
7. Search for processes that contain the following strings and terminates them:
   
   • ATUPDATER.EXE
   • AUPDATE.EXE
   • AUTODOWN.EXE
   • AUTOTRACE.EXE
   • AUTOUPDATE.EXE
   • AVPUPD.EXE
   • AVWUPD32.EXE
   • AVXQUAR.EXE
   • CFIAUDIT.EXE
   • DRWEBUPW.EXE
   • ICSSUPPNT.EXE
   • ICSUPP95.EXE
   • loadclean.exe
   • loader.exe
   • LUALL.EXE
   • MCUPDATE.EXE
   • NUPGRADE.EXE
   • runddl.exe
   • serve.exe
   • UPDATE.EXE

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

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. Restart the computer in Safe mode or VGA mode.
4. Run a full system scan and delete all the files detected as Trojan.Noupdate.B.
5. Delete the value that was added to the registry.
6. Reset the Internet Explorer Home and Search pages.
7. Reverse the changes made to the Hosts file.
   

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"

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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.

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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).
  
  

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  Note: If this Trojan is running, you may not be able to run LiveUpdate. If you cannot, download the definitions using the Intelligent Updater (see the next bulleted item).

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• 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. Restarting the computer in Safe mode or VGA mode
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode or VGA mode.

• For Windows 95, 98, Me, 2000, or XP users, restart the computer in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode."
• For Windows NT 4 users, restart the computer in VGA mode.

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 Trojan.Noupdate.B, write down the location and file name, and then click Delete.

5. Deleting the value from the registry

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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.

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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_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
4. In the right pane, delete the value:
   
   "reg32"=%Windows%eg32.exe"
   
   
5. Exit the Registry Editor.

6. Reseting the Internet Explorer home page

1. Start Internet Explorer.
2. Click the Tools menu > Internet Options.
3. On the Programs tab, click "Reset Web Settings."
4. In the Reset Web Settings message box, make sure that "Also reset my home page" is selected, and then click Yes.

7. Reversing the changes made to the Hosts file
The Hosts file is not found on all the computers, and if it does exist, the location can vary. For example, if the file exists in Windows 98, it will usually be in C:Windows; and in Windows 2000, it is in the C:WINNTSYSTEM32DRIVERSETC folder. Also, there may be multiple copies of this file in different locations.

The most efficient way to locate the file is to search for it.

Follow the instructions for your operating system:

• Windows 95/98/Me/NT/2000
  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:
     
     hosts
     
     
  4. Click Find Now or Search Now.
  5. For each one that you find, note its location. (This is displayed in the "In Folder" column.)
  6. Right-click each file, and then click "Open With."
  7. Deselect the "Always use this program to open this program" check box.
  8. Scroll through the list of programs and double-click Notepad.
  9. When the file opens, delete all the entries in the Hosts file, except for the following line:
     
     127.0.0.1     localhost
     
     
  10. Close Notepad and save your changes when prompted.
      
      
• Windows XP
  1. Click Start, and then click Search.
  2. Click All files and folders.
  3. In the "All or part of the file name" box, type:
     
     hosts
     
     
  4. Verify that "Look in" is set to "Local Hard Drives" or to (C:).
  5. Click "More advanced options."
  6. Check "Search system folders."
  7. Check "Search subfolders."
  8. Click Search.
  9. Click Find Now or Search Now.
  10. For each one that you find, note its location. (This is displayed in the "In Folder" column.)
  11. Right-click each file, and then click "Open With."
  12. Deselect the "Always use this program to open this program" check box.
  13. Scroll through the list of programs and double-click Notepad.
  14. When the file opens, delete all the entries in the Hosts file except for the following line:
      
      127.0.0.1     localhost
      
      
  15. Close Notepad and save your changes when prompted.