Infostealer.Bancos.B

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Discovered: July 31, 2003
Updated: February 13, 2007 12:54:48 PM
Also Known As: PWSteal.Bancos.B
Type: Trojan Horse


Infostealer.Bancos.B is a Trojan horse that mimics the online interfaces of certain Brazilian banks to steal account information. It is a minor variant of Infostealer.Bancos. This Trojan may arrive as an email attachment named "book1.exe."

See the "Technical Details" section for an illustration of the message box that the dropper displays after the email attachment is executed.



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

Antivirus Protection Dates

  • Initial Rapid Release version August 01, 2003
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version August 01, 2003
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date August 01, 2003

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Heather Shannon

Discovered: July 31, 2003
Updated: February 13, 2007 12:54:48 PM
Also Known As: PWSteal.Bancos.B
Type: Trojan Horse


When the email attachment is executed, the dropper displays a message box:





If you click Continuar, the Trojan will install the following files in the %System% folder:

    • Msvbvm60.dll: A legitimate .dll file, which is 1,388,544 bytes in length.
    • Winmax.exe: The Trojan, which is 258,048 bytes long.

NOTE: %System% is a variable. The Trojan locates the System folder and copies itself to that location. By default, this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

After the files are dropped, the Trojan is launched.

Trojan horse
When the Trojan executes, it performs the following actions:
  1. May copy itself as one or more of the following files:
    • C:\WINDOWS\System\win.exe
    • %System%\winmax.exe

  2. May add one or more of the following values:

    "WinMenssage" = "%System%\winmax.exe"
    "winzip"="C:\WINDOWS\system\win.exe"

    to the registry key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

    so that the Trojan runs when you start Windows.

  3. If the file, C:\BancoBrasil\officeIE\officeIE.CAB, exists, the Trojan will move it to C:\officeIE.CAB.

  4. Monitors the active Internet Explorer windows, waiting for you to open a Web page that matches the characteristics of certain banking sites. When such a site is opened, the Trojan displays one of several login screens, which are selected according to the title of the bank's Web page.

    If the Web page is titled "GerenciadorFinanceiro," it will display:


    If the Web page is titled "Bankline," it will display:



    If the Web page is titled "AAPF," it will display:



    If the Web page is titled "InternetBankingCaixa," it will display:



    If the Web page is titled Bradesco, it will display:


The information entered on these screens may then be uploaded to an FTP site that the Trojan's author controls. However, Symantec Security Response has not been able to reproduce this behavior.

Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • 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.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a 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.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. 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.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Heather Shannon

Discovered: July 31, 2003
Updated: February 13, 2007 12:54:48 PM
Also Known As: PWSteal.Bancos.B
Type: Trojan Horse


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. Do one of the following:
    • For Windows 95, 98, Me, 2000, or XP users: Restart the computer in Safe mode.
    • For Windows NT 4 users: Restart the computer in VGA mode.
  4. Run a full system scan and delete all the files detected as Infostealer.Bancos.B.
  5. If necessary, restore the MSVBVM60.DLL file.
  6. Reverse the changes that the Trojan made to the registry.
  7. Restore the officeIE.CAB file.
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:
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
    • For Windows 95, 98, Me, 2000, or XP users: Restart the computer in Safe mode. For instructions, refer to 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
5. To restore the MSVBVM60.DLL file

The Trojan installs its own version of MSVBVM60.DLL in the %System% directory. You may wish to replace it with a backup copy of the original file.

6. To reverse the changes made to the registry

CAUTION
: 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. 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_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run

  4. In the right pane, delete the values:

    "WinMenssage"="%System%\winmax.exe"
    "winzip"="C:\WINDOWS\system\win.exe"

  5. Exit the Registry Editor.


7. To restore the officeIE.CAB file

If the file, C:\officeIE.CAB, exists on your system, you may need to move it back to C:\BancoBrasil\officeIE\officeIE.CAB to restore the functionality of your software.

Writeup By: Heather Shannon