Infostealer.Bancos

SUMMARY

Infostealer.Bancos is a generic detection for various threats that steal passwords entered into forms in Web browsers.

Note : Definitions prior to May 10, 2006 may detect this threat as PWSteal.Bancos

Protection

• Virus Definitions (LiveUpdate™ Weekly) July 23, 2003
• Virus Definitions (Intelligent Updater) July 18, 2003

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 Trigger: Often triggered by visiting a financial Web site.
• Releases Confidential Info: Collects passwords

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Symantec antivirus programs use Infostealer.Bancos as a generic detection when detecting many individual but varied password stealing programs.

Infostealer.Bancos variants steal passwords to financial Web sites by either:

• Displaying fake browser windows that look like the sign in pages for legitimate financial Web sites.
• Logging data entered into legitimate browser windows that belong to financial institutions.

In these cases, a generic detection is used because it protects against many password stealers that share similar characteristics.

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 Infostealer.Bancos.
5. Delete any values that were added to the registry.
6. Windows 95/98/Me only: Remove any references to the infected files, which the password stealer added to the Win.ini and System.ini files.
7. Clear the Temporary Internet Files folder, if required
   

For specific details on each of these steps, read the following instructions

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Note: The procedures described in this document are complex and assume that you are familiar with basic Windows and DOS procedures. If you are not, then we suggest that you obtain the services of a qualified computer consultant.

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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"

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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. 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 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. To restart 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. 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 as infected with Infostealer.Bancos, write down the name and location of the file, and then click Delete. You will need this information in the following sections.
   
   If the infected files are detected in the Temporary Internet FilesContent.IE5, due to the design of the operating system, you will not be able to delete them. Write down the entire path and file name. Then, later in the removal, follow the instructions in section 7.

5. To delete any values that were added to 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 > Run.
2. Type regedit
   
   Then click OK.
   
   
3. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
   
4. Refer to the list of the infected files that you created while following the instructions in the previous section. In the right pane, look at the entries in the Name and Data columns.
   
   
5. If you find an entry that refers to a file detected as infected, select the entry, press Delete, and then click Yes to confirm.
   
   
6. On Windows 95/98/Me computers, navigate to and select the following key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRunServices
   
   
7. Refer to the list of the infected files that you created while following the instructions in the previous section. In the right pane, look at the entries in the Name and Data columns.
   
   
8. If you find an entry that refers to a file detected as infected, select the entry, press Delete, and then click Yes to confirm.
   
   
9. Exit the Registry Editor.
   
   
10. Do one of the following:
    
    • If you are running Windows NT/2000/XP, and the scan did not detect the infected files in the Temporary Internet FilesContent.IE5 folder, you are done. Restart the computer in Normal mode. For instructions, read the section on returning to Normal mode in the document, "How to start the computer in Safe Mode."
    • If you are running Windows NT/2000/XP, and the scan detected the infected files in the Temporary Internet FilesContent.IE5 folder, skip to section 7.
    • If you are running Windows 95/98/Me, proceed with section 6.

6. Windows 95/98/Me only: To remove references to infected files added to Win.ini and System.ini files
If you are running Windows 95/98/Me, follow these steps:

1. The function you perform depends on your operating system:
   1. Windows 95/98: Go to step B.
   2. Windows Me: If you are running Windows Me, the Windows Me file-protection process may have made a backup copy of the Win.ini and System.ini files that you need to edit. If these backup copies exist, they will be in the C:WindowsRecent folder. Symantec recommends that you delete these files before continuing with the steps in this section. To do this:
      1. Start Windows Explorer.
      2. Browse to and select the C:WindowsRecent folder.
      3. In the right pane, select the Win.ini file and the System.ini files, and then delete them. Windows will regenerate them.
         
2. Click Start > Run.
   
3. Type the following, and then click OK.
   
   edit c:windowswin.ini
   
   

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   Note: If Windows is installed in a different location, make the appropriate path substitution.

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   WARNING: The following steps instruct you to remove the text from the load= and run= lines of the Win.ini file. If you are using older programs, they may load at startup from one of these lines.
   
   The password stealer can add lines, such as load=c:windows emppkg2350.exe or run=hpfsched <blank spaces> msrexe.exe. (In this example, hpfsched is a legitimate program, but msrexe.exe is part of the password stealer.)
   
   If you are sure that the text contained in these lines is for the programs that you normally use, then we suggest that you do not remove it. If you are not sure, but the text does not refer to the file names you previously noted, then you can prevent the lines from loading by placing a semicolon (;) in the first character position of the line.
   
   For example:
   
   ; run=accounts.exe
   

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4. In the [windows] section of the file, look for a line that begins with:
   
   load=
   
   
5. Position the cursor immediately to the right of the equal (=) sign.
   
   
6. Press Shift+End to select all the text to the right of the equal sign, and then press Delete.
   
   
7. Repeat steps E. and F. for the run= line, which is usually beneath the load= line.
   
   
8. Click Start > Run.
   
   
9. Type the following.
   
   edit c:windowssystem.ini
   
   and then click OK
   
   

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   Note: If Windows is installed in a different location, make the appropriate path substitution.

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10. In the [boot] section, which is usually located near the top of the file, find the line that begins with shell=explorer.exe.
    
    
11. Position the cursor immediately to the right of explorer.exe.
    
    
12. Press Shift+End to select all the text to the right of explorer.exe, and then press Delete.
    
    When you are finished, the line should look like this:
    
    shell=explorer.exe
    
    
13. Click File > Exit > Yes (click Yes when you are prompted to save the changes).
    

7. To clear the Temporary Internet Files folder, if required

1. Restart the computer in Normal mode. For instructions, read the section on returning to Normal mode in the document, "How to start the computer in Safe Mode."
   
   
2. Log on to the computer using the name that was shown in the path that you wrote down in step 4c.
   
   For example, if the path was:
   
   C:Documents and SettingLindaLocal SettingsTemporary Internet Filesqrwmqczd.dll
   
   log on to the computer as Linda.
   
   
3. Start Internet Explorer.
4. Click Tools > Internet Options.
5. In the Temporary Internet Files section, click the Delete Files button.
6. Check Delete all offline content, and then click OK.