Infostealer.Etavirp.A

SUMMARY

Infostealer.Etavirp.A is a password-stealing Trojan. It logs keypresses from certain Web pages based on the site domain, page header, and page contents. The Trojan typically arrives as an email attachment.

NOTE : Definitions prior to May 10, 2006 may detect this threat as PWSteal.Etavirp.A

Protection

• Virus Definitions (LiveUpdate™ Weekly) June 9, 2004
• Virus Definitions (Intelligent Updater) June 9, 2004

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
• Releases Confidential Info: Logs keystrokes and send it to a predetermined email address.
• Degrades Performance: Continuous writing of files and refreshing of registry keys may impact system performance.

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

When Infostealer.Etavirp.A is executed, it performs the following actions:

1. Creates the following files:
   
   • %System%MSlib32.dll
   • %System%Mssdk32.dll
   • %Windir%systemuser32.exe
     
     Notes:
   • %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).
   • %Windir% is a variable that refers to the Windows installation folder. By default, this is C:Windows (Windows 95/98/Me/XP)or C:Winnt (Windows NT/2000).
     
     
2. Adds the value:
   
   "UserMansger" = "User32.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
   so that the Trojan runs every time Windows starts.
   
   
3. May add the value:
   
   "Shell" = "Explorer.exe %Windir%systemUser32.exe"
   
   to the registry key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindows NTCurrentVersionWinlogon
   
   so that the Trojan runs every time another program is started.
   
   
4. Monitors active Internet Explorer windows.
   
   
5. Logs keypresses, when a site that matches the characteristics of certain banking sites is visited.
   
   
6. May send collected information to a mail account that the author predefines.
   
   
7. Goes into a loop, infinitely recreating the files and resetting the registry keys.

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 (Windows 95/98/Me), or Safe mode with Command Prompt (Windows 2000/XP).
4. Reverse the changes made to the registry.
5. Run a full system scan and delete all the files detected as Infostealer.Etavirp.A
   

For 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, re-enable 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 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 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.

Note: If you receive error messages when you run LiveUpdate, first follow the instructions in section 8. Then return to section 2 and continue with the removal.


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 section 4.

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 section 4.

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 section 4.

4. To reverse the changes made to 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 keys only. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Do one of the following:
   • Windows 2000/XP: Skip to step b.
   • Windows 95/98/Me: Click Start > Run.
     
     
2. Type the following:
   
   regedit
   
   
3. Do one of the following:
   • Windows 2000/XP: Press Enter.
   • Windows 95/98/Me: Click OK.
     
     
4. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   
5. In the right pane, delete the value:
   
   "UserMansger" = "User32.exe"
   
   
6. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindows NTCurrentVersionWinlogon
   
   
7. In the right pane, double-click:
   
   Shell
   
   
8. Change:
   
   explorer.exe %Windir%systemUser32.exe
   
   to:
   
   explorer.exe
   
   
9. Exit the Registry Editor.

5. 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 file."
2. Run a full system scan.
3. If any files are detected as infected with Infostealer.Etavirp.A, click Delete.