Trojan.Stranget.B

SUMMARY

Trojan.Stranget.B is a Trojan horse that logs keystrokes, steals passwords and system information, and sends it to a remote attacker. It also downloads files and opens an FTP server by exploiting the Microsoft Internet Explorer CreateTextRange Remote Code Execution Vulnerability (as described in Microsoft Security Bulletin MS06-013).

It is reported that the Trojan horse is downloaded by another threat, Download.Fullalc from a predetermined Web site.

Note: Virus definitions prior to March 27th, 2006 may detect this threat as Keylogger.Stranget.B.

Protection

• Virus Definitions (LiveUpdate™ Daily) March 27, 2006
• Virus Definitions (LiveUpdate™ Weekly) March 29, 2006
• Virus Definitions (Intelligent Updater) March 27, 2006
• Virus Definitions (LiveUpdate™ Plus) March 27, 2006

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
• Payload: Attempts to download and execute files from specific URLs.
• Releases Confidential Info: Gathers system information and passwords, and sends it to the remote attacker.
• Degrades Performance: Downloading of files may degrade network performance
• Causes System Instability: Ends running processes which may impact the performance of certain applications.
• Compromises Security Settings: Ends processes, some of which may be security related.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

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

1. Creates a copy of itself as %Windir%fyt m32.exe.
   
   Note: %Windir% is a variable that refers to the Windows installation folder. By default, this is C:Windows or C:Winnt.
   
   
2. Adds the value:
   
   "ujm" = "%Windir%fyt m32.exe"
   
   to the registry subkey:
   
   HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
   
   so that it runs every time Windows starts.
   
   
3. Adds the values:
   
   "InstallDate" = "[DATE THE TROJAN WAS EXECUTED]"
   "InstallPath" = "PATH FROM WHICH TROJAN WAS RUN"
   "Update2" = "[DATE]"
   
   to the registry subkey:
   
   HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersion
   
   as an infection marker and to store the date and time it last downloaded an update.
   
   
4. Creates and loads the file %Windir%fytmn32.dll, which contains its keylogging functionality.
   
   
5. It is reported that the Trojan registers this .dll file as a Browser Helper Object by creating registry entries under the following subkeys:
   
   HKEY_CLASSES_ROOTAppID{85B17391-3706-4454-B73F-38D6E74B0480}
   HKEY_CLASSES_ROOTAppIDFG.DLL
   HKEY_CLASSES_ROOTCLSID{B4B1D862-DD79-47E6-B29B-2AD5A9A5D885}
   HKEY_CLASSES_ROOTCLSID{FBFD2ED1-14EA-4D3A-B88E-DADF7C058766}
   HKEY_CLASSES_ROOTFG.FGHelper
   HKEY_CLASSES_ROOTFG.FGHelper.1
   HKEY_CLASSES_ROOTFG.SubHelper
   HKEY_CLASSES_ROOTFG.SubHelper.1
   
   
6. Monitors URLs visited in browsers, and watches for the following strings encrypted in its body:
   
   
   • online
   • mail
   • ftp
   • web
   • acce
   • enter
   • login
   • pass
   • private
   • admin
   • magane
   • lead
   • mortg
   • corpora
   • panel
   • base
   • data
   • network
   • sql
   • terminal
   • connec
   • send
     
     
7. Stores logged keystrokes in the file %Windir%fytkbd.txt.
   
   
8. Logs URLs visited with the corresponding request strings in the file %Windir%fyteq.txt.
   
   
9. Exploits the Microsoft Internet Explorer CreateTextRange Remote Code Execution Vulnerability (as described in Microsoft Security Bulletin MS06-013).
   
   
10. Downloads a file from a URL stored in its body, saves the file as %Windir%fyt~url.exe, and runs the file.
    
    Note: The sample Symantec received does not contain a URL, but may change as the Trojan is extensible.
    
    
11. Creates the file %Windir%fyt~tmp636, in which stores the following information gathered from the compromised computer:
    
    
    • Passwords gathered from Protected Storage
    • Cached passwords
    • Password hashes gathered from the SAM database
    • RAS phonebook entries
      
      
12. Gathers system information by running shell commands, and saving the output in files.
    
    
13. Creates the file %Windir%fyt~view636, in which it stores the output of the command netstat -a -n.
    
    
14. Creates the file %Windir%fyt~start636, in which it stores the output of the command netstat -a -n.
    
    
15. Creates the file %Windir%fyt~ipcfg636, in which it stores the output of the command ipconfig /all.
    
    
16. Copies the contents of the files ~view636, ~start636, ~ipcfg636, ~tmp636 into the file %Windir%fyt~res636.
    
    
17. Attempts to send the file ~res636 to the remote attacker through email and FTP. The sample received contains a blank email address to send to, and it is reported that the Trojan contains its own SMTP engine to send information to an address in the mail.ru domain.
    
    
18. Uploads the file via FTP to the domain www.projecx.net.
    
    
19. Sends the following files to the attacker via the above methods:
    
    
    • %Windir%fytkbd.txt
    • %Windir%fyteq.txt
      
      
20. Ends the following processes, some of which may be security related:
    
    
    • ZONEALARM.EXE
    • WFINDV32.EXE
    • WEBSCANX.EXE
    • VSSTAT.EXE
    • VSHWIN32.EXE
    • VSECOMR.EXE
    • VSCAN40.EXE
    • VETTRAY.EXE
    • VET95.EXE
    • TDS2-NT.EXE
    • TDS2-98.EXE
    • TCA.EXE
    • TBSCAN.EXE
    • SWEEP95.EXE
    • SPHINX.EXE
    • SMC.EXE
    • SERV95.EXE
    • SCRSCAN.EXE
    • SCANPM.EXE
    • SCAN95.EXE
    • SCAN32.EXE
    • SAFEWEB.EXE
    • RESCUE.EXE
    • RAV7WIN.EXE
    • RAV7.EXE
    • PERSFW.EXE
    • PCFWALLICON.EXE
    • PCCWIN98.EXE
    • PAVW.EXE
    • PAVSCHED.EXE
    • PAVCL.EXE
    • PADMIN.EXE
    • OUTPOST.EXE
    • NVC95.EXE
    • NUPGRADE.EXE
    • NORMIST.EXE
    • NMAIN.EXE
    • NISUM.EXE
    • NAVWNT.EXE
    • NAVW32.EXE
    • NAVNT.EXE
    • NAVLU32.EXE
    • NAVAPW32.EXE
    • N32SCANW.EXE
    • MPFTRAY.EXE
    • MOOLIVE.EXE
    • LUALL.EXE
    • LOOKOUT.EXE
    • LOCKDOWN2000.EXE
    • JEDI.EXE
    • IOMON98.EXE
    • IFACE.EXE
    • ICSUPPNT.EXE
    • ICSUPP95.EXE
    • ICMON.EXE
    • ICLOADNT.EXE
    • ICLOAD95.EXE
    • IBMAVSP.EXE
    • IBMASN.EXE
    • IAMSERV.EXE
    • IAMAPP.EXE
    • F-STOPW.EXE
    • FRW.EXE
    • FP-WIN.EXE
    • F-PROT95.EXE
    • F-PROT.EXE
    • FPROT.EXE
    • FINDVIRU.EXE
    • F-AGNT95.EXE
    • ESPWATCH.EXE
    • ESAFE.EXE
    • ECENGINE.EXE
    • DVP95_0.EXE
    • DVP95.EXE
    • CLEANER3.EXE
    • CLEANER.EXE
    • CLAW95CF.EXE
    • CLAW95.EXE
    • CFINET32.EXE
    • CFINET.EXE
    • CFIAUDIT.EXE
    • CFIADMIN.EXE
    • BLACKICE.EXE
    • BLACKD.EXE
    • AVWUPD32.EXE
    • AVWIN95.EXE
    • AVSCHED32.EXE
    • AVPUPD.EXE
    • AVPTC32.EXE
    • AVPM.EXE
    • AVPDOS32.EXE
    • AVPCC.EXE
    • AVP32.EXE
    • AVP.EXE
    • AVNT.EXE
    • AVKSERV.EXE
    • AVGCTRL.EXE
    • AVE32.EXE
    • AVCONSOL.EXE
    • AUTODOWN.EXE
    • APVXDWIN.EXE
    • TROJAN.EXE
    • ACKWIN32.EXE
    • _AVPM.EXE
    • _AVPCC.EXE
    • _AVP32.EXE
      
      
21. Downloads updates to itself at regular intervals. The sample received contains a blank IP or domain from which updates are downloaded.
    
    
22. The Trojan is extensible and may be updated by the attacker. Updated versions of the threat may include the following functionality:
    
    
    • Email address to which it sends files (The sample analyzed did not contain any.)
    • FTP server domain, IP address, user name, and password used to upload files (Some domains found in the sample analyzed that may have been used in the past are, Inf-x.org, 66.98.132.67, and www.projecx.net.)
    • A list of strings to monitor
    • A URL that the Trojan will use to download and run a file
    • The port number it uses to start an FTP server
    • IP address used to download its updates

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. Run a full system scan and delete all the files detected.
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:

• 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: 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 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 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.
   • 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.

Important: If you are unable to start your Symantec antivirus product or the product reports that it cannot delete a detected file, you may need to stop the risk from running in order to remove it. To do 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 the next section.

Warning messages may be displayed when the computer is restarted, since the threat may not be fully removed at this point. You can ignore these messages and click OK. These messages will not appear when the computer is restarted after the removal instructions have been fully completed. The messages displayed may be similar to the following:

Title: [FILE PATH]
Message body: Windows cannot find [FILE NAME]. Make sure you typed the name correctly, and then try again. To search for a file, click the Start button, and then click Search.


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.
   
   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. Navigate to the subkey:
   
   HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionRun
   
   
5. In the right pane, delete the value:
   
   "ujm" = "%Windir%fyt m32.exe"
   
   
6. Navigate to the subkey:
   
   HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersion
   
   
7. In the right pane, delete the values:
   
   "InstallDate" = "[DATE THE TROJAN WAS EXECUTED]"
   "InstallPath" = "[DIRECTORY IN WHICH THE TROJAN WAS EXECUTED]"
   "Update2" = "[DATE]"
   
   
8. Navigate to and delete the subkeys:
   
   HKEY_CLASSES_ROOTAppID{85B17391-3706-4454-B73F-38D6E74B0480}
   HKEY_CLASSES_ROOTAppIDFG.DLL
   HKEY_CLASSES_ROOTCLSID{B4B1D862-DD79-47E6-B29B-2AD5A9A5D885}
   HKEY_CLASSES_ROOTCLSID{FBFD2ED1-14EA-4D3A-B88E-DADF7C058766}
   HKEY_CLASSES_ROOTFG.FGHelper
   HKEY_CLASSES_ROOTFG.FGHelper.1
   HKEY_CLASSES_ROOTFG.SubHelper
   HKEY_CLASSES_ROOTFG.SubHelper.1
   
   
9. Exit the Registry Editor.