Trojan.Bomka

SUMMARY

Trojan.Bomka is a Trojan horse program that drops several threats on the compromised computer and uses rootkit techniques to hide its files.

Protection

• Virus Definitions (LiveUpdate™ Daily) January 25, 2006
• Virus Definitions (LiveUpdate™ Weekly) January 25, 2006
• Virus Definitions (Intelligent Updater) January 25, 2006
• Virus Definitions (LiveUpdate™ Plus) January 25, 2006

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: Low
• Payload: May open a back door.

Distribution

• Distribution Level: Low
• Ports: Predetermined Port.

TECHNICAL DETAILS

The Trojan may arrive as an attachment to an email spammed out by Trojan.Spamlia with a link to one of the following domains:

• [http://]www.nice-movie-laugh.com/[REMOVED]
• [http://]www.nice-movie-jokes.com/[REMOVED]
• [http://]www.movielaugh.com/[REMOVED]
• [http://]www.moviejump.com/[REMOVED]
• [http://]www.movie-smile.com/[REMOVED]
• [http://]www.goodmoviejokes.com/[REMOVED]
• [http://]www.good-movie-smile.com/[REMOVED]
• [http://]www.good-movie-play.com/[REMOVED]
• [http://]www.good-movie-laugh.com/[REMOVED]
• [http://]www.good-movie-jokes.com/[REMOVED]
• [http://]www.goodmovielaugh.com/[REMOVED]
• [http://]www.nicemoviesmile.com/[REMOVED]
• [http://]www.nicemovieplay.com/[REMOVED]
• [http://]www.nicemovielaugh.com/[REMOVED]
• [http://]www.movie-play.com/[REMOVED]
• [http://]www.movie-laugh.com/[REMOVED]
• [http://]www.goodmoviesmile.com/[REMOVED]
• [http://]www.goodmovieplay.com/[REMOVED]
  

The downloaded executable file pretends to be a legitimate video codec software and typically has one of the following filenames:

• IETOOL.EXE
• VideoCodec3_05b_[NUMBER].exe

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

1. Drops one or more of the following files, which are detected as other Trojans:
   
   • %System%gtrack.dll (Detected as Trojan.Adclicker).
   • %System%kaboom.dll (Detected as Trojan.Adclicker).
   • %System%msx.dll (Detected as Trojan.Horse).
   • %System%iewatch.exe (Detected as Trojan.Adclicker).
   • %System%icqchk.exe (Detected as Backdoor.Trojan).
   • %System%kpsf.exe (Detected as Backdoor.HackDefender).
   • %System%kpsf.sys (Detected as Backdoor.HackDefender).
     
     Note: %System% is a variable that refers to the System folder. By default this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).
     
     
2. Adds the value:
   
   "IEAgent update check" = "[TROJAN FILE NAME]"
   "runapp" = "[TROJAN FILE NAME]"
   
   to the registry subkey:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   so that it runs every time Windows starts.
   
   
3. Creates some of the following registry subkeys:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerBrowser Helper Objects
   {4BC9A7AC-2329-49D0-B07F-5FE484029DC2}
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerBrowser Helper Objects
   {A853979C-2A9A-4ACB-8975-5740A7E26CB4}
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerBrowser Helper Objects
   {CC56A1F3-9B83-45FF-8CB6-D58959492F0F}
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerBrowser Helper Objects
   {037CE595-57CB-4EB5-9775-97BC112F3BB3}
   HKEY_CLASSES_ROOTKaboom.IEagent
   HKEY_CLASSES_ROOTKaboom.IEagent.1
   HKEY_CLASSES_ROOTWatcher.GoogleTracker
   HKEY_CLASSES_ROOTWatcher.GoogleTracker.1
   HKEY_CLASSES_ROOTdo.msx
   HKEY_CLASSES_ROOTdo.msx.1
   HKEY_CLASSES_ROOTCLSID{4BC9A7AC-2329-49D0-B07F-5FE484029DC2
   HKEY_CLASSES_ROOTCLSID{CC56A1F3-9B83-45FF-8CB6-D58959492F0F}
   HKEY_CLASSES_ROOTCLSID{A853979C-2A9A-4ACB-8975-5740A7E26CB4}
   HKEY_CLASSES_ROOTCLSID{037CE595-57CB-4EB5-9775-97BC112F3BB3}
   HKEY_CLASSES_ROOTInterface{BAA919E5-FD47-4D7E-95AB-5B2CDA493358}
   HKEY_CLASSES_ROOTTypeLib{E0C0FC76-CC5E-46E2-B77A-4C2ADD965B9F}
   HKEY_CLASSES_ROOTInterface{D861BD5E-E1E7-4E5E-AB15-CB347FBDBC6D}
   HKEY_CLASSES_ROOTTypeLib{023E6659-1A0A-4724-9273-66EA06A82C98}
   HKEY_CLASSES_ROOTInterface{88B67E52-A8D4-44AF-A199-DEE96469B7AF}
   HKEY_CLASSES_ROOTTypeLib{B73EF4A8-B8B1-4683-8D21-AA1C1A46CAD7}
   HKEY_CLASSES_ROOTInterface{7E951E5E-C57B-41ED-806F-1FBB2E4538C1}
   HKEY_CLASSES_ROOTTypelib{3E55D5AA-2006-4572-BCF3-643D6AAB9063}
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftSUW
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftIEAgent
   HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesicqupd
   
   
4. Creates a device service, a rootkit detected as Backdoor.HackDefender. This service enables the Trojan to hide all the dropped files and registry subkeys it creates and has the following properties:
   
   Display Name: ICQ Update Service
   Service Name: ICQUPD
   Image Path: %System%kpsf.sys
   
   
5. May also act as a back door, opening a predetermined port on the compromised computer.

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 Safe mode with Command Prompt.
4. Run a full system scan and delete all the files detected.
5. 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:

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

Note: 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:
  • If you use Norton AntiVirus 2006, Symantec AntiVirus Corporate Edition 10.0, or newer products, LiveUpdate definitions are updated daily. These products include newer technology.
  • If you use Norton AntiVirus 2005, Symantec AntiVirus Corporate Edition 9.0, or earlier products, LiveUpdate definitions are updated weekly. The exception is major outbreaks, when definitions are updated more often.
• 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 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 restart the computer in Safe mode or Safe mode with Command Prompt
Follow the instructions for your operating system.

Windows 95/98/Me
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode. For instructions, read the document: How to start the computer in Safe Mode.

Once in Safe mode (this could take some time) proceed with the next section.

Windows 2000

1. Shut down the computer, and then turn off the power. Wait for at least 30 seconds, and then restart the computer
2. When you see the black and white Starting Windows bar at the bottom of the screen, press the F8 key (usually on the top row of the keyboard).
3. In the Windows 2000 Advanced Options Menu, select Safe mode with Command Prompt, and then press Enter.
   
   Once the computer opens to a window with a command prompt (you should see a line of text and a blinking cursor), proceed with the next section.

Windows XP

1. Shut down the computer, and then turn off the power. Wait for at least 30 seconds, and then restart the computer. The computer begins processing a set of instructions known as the Basic Input/Output System (BIOS). What is displayed depends on the BIOS manufacturer. Some computers display a progress bar that refers to the word BIOS, while others may not display any indication that this process is occurring.
2. As soon as the BIOS has finished loading, begin tapping the F8 key on your keyboard. Continue to do so until the Windows Advanced Options menu appears. If you begin tapping the F8 key too soon, some computers will display a "keyboard error" message. To avoid this, restart the computer and try again.
3. In the Windows 2000 Advanced Options Menu, select Safe mode with Command Prompt, and then press Enter.
   
   Once the computer opens to a window with a command prompt (you should see a line of text and a blinking cursor), proceed with the next section.

4. 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.
   • 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, click Delete.
   
   
   5. 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.
   
   Note: If the registry editor fails to open the threat may have modified the registry to prevent access to the registry editor. Security Response has developed a tool to resolve this problem. Download and run this tool, and then continue with the removal.
   
   
4. Delete the following registry subkeys:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerBrowser Helper Objects
   {4BC9A7AC-2329-49D0-B07F-5FE484029DC2}
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerBrowser Helper Objects
   {A853979C-2A9A-4ACB-8975-5740A7E26CB4}
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerBrowser Helper Objects
   {CC56A1F3-9B83-45FF-8CB6-D58959492F0F}
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerBrowser Helper Objects
   {037CE595-57CB-4EB5-9775-97BC112F3BB3}
   HKEY_CLASSES_ROOTKaboom.IEagent
   HKEY_CLASSES_ROOTKaboom.IEagent.1
   HKEY_CLASSES_ROOTWatcher.GoogleTracker
   HKEY_CLASSES_ROOTWatcher.GoogleTracker.1
   HKEY_CLASSES_ROOTdo.msx
   HKEY_CLASSES_ROOTdo.msx.1
   HKEY_CLASSES_ROOTCLSID{4BC9A7AC-2329-49D0-B07F-5FE484029DC2
   HKEY_CLASSES_ROOTCLSID{CC56A1F3-9B83-45FF-8CB6-D58959492F0F}
   HKEY_CLASSES_ROOTCLSID{A853979C-2A9A-4ACB-8975-5740A7E26CB4}
   HKEY_CLASSES_ROOTCLSID{037CE595-57CB-4EB5-9775-97BC112F3BB3}
   HKEY_CLASSES_ROOTInterface{BAA919E5-FD47-4D7E-95AB-5B2CDA493358}
   HKEY_CLASSES_ROOTTypeLib{E0C0FC76-CC5E-46E2-B77A-4C2ADD965B9F}
   HKEY_CLASSES_ROOTInterface{D861BD5E-E1E7-4E5E-AB15-CB347FBDBC6D}
   HKEY_CLASSES_ROOTTypeLib{023E6659-1A0A-4724-9273-66EA06A82C98}
   HKEY_CLASSES_ROOTInterface{88B67E52-A8D4-44AF-A199-DEE96469B7AF}
   HKEY_CLASSES_ROOTTypeLib{B73EF4A8-B8B1-4683-8D21-AA1C1A46CAD7}
   HKEY_CLASSES_ROOTInterface{7E951E5E-C57B-41ED-806F-1FBB2E4538C1}
   HKEY_CLASSES_ROOTTypelib{3E55D5AA-2006-4572-BCF3-643D6AAB9063}
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftSUW
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftIEAgent
   HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesicqupd
   
   
5. Navigate to the subkey:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   
6. In the right pane, delete the values:
   
   "IEAgent update check" = "[DROPPED_TROJAN_FILE]"
   "runapp" = "[DROPPED_TROJAN_FILE]"
   
7. Exit the Registry Editor.