Threat Explorer

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16 July 2003
13 February 2007
Also Known As:
Downloader-DI [McAfee], TrojanProxy.Win32.Webber.10 [K, Troj/Webber-A [Sophos], Trojan.Download.Berbew
Systems Affected:

Downloader.Berbew is a Trojan Horse that attempts to download Backdoor.Berbew from the Internet and execute it on the local system. This Trojan was spammed to a large number of individuals in an email message claiming to be from Citibank Accounting or

Downloader.Berbew typically arrives as an attachment with a .pif extension, such as:
  • www.citybankhomeloan.htm.pif
  • E-Loan-Appraiser-Results.pif
  • (This is a password protected zip file.)

  • Detections for this threat were updated on April 7, 2004 to account for the discovery of a minor variant.
  • Virus definitions dated June 6, 2006 or earlier may detect this threat as Trojan.Download.Berbew.

Antivirus Protection Dates

  • Initial Rapid Release version 16 July 2003
  • Latest Rapid Release version 08 August 2016 revision 023
  • Initial Daily Certified version 16 July 2003
  • Latest Daily Certified version 09 August 2016 revision 001
  • Initial Weekly Certified release date 16 July 2003
Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Downloader.Berbew may arrive as an attachment to spam email, such as, but not limited to, one of the following:
  • From (spoofed): Citibank Accounting <>
    Subject: Re: Your credit application
    Message Body:
    Dear sir,
    Thank you for your online application for a Citibank Home Equity Loan. In order to be approved for any loan application we pull your Credit Profile and Chexsystems information, which didn't satisfy our minimum needs. Consequently, we regret to say that we cannot approve you for Citibank Home Equity Loan at this time.
    *Attached are copy of your Credit Profile and Your Application that you submitted with us.
    Please take a close look at it, you will receive hard copy by mail withing next few days.

    Attachment: (5,664 bytes)

  • From: (spoofed) E-Loan Consumer Department <>
    Subject: Re: Your E-Loan Refinance Application Declined
    Message body:

    Dear sir,

    Thank you for your recent online Refinance Application with E-Loan Inc.
    Apparently you have moved from your current home address a couple of months ago,
    so we coulnd't verify your identity with Credit Bureaus and Chexsystems. We are
    sorry for any inconvenience. Attached are scanned copies of your Home Value, Grant
    Deeds and your current Credit Profile from 3 major Credit Bureaus. Take a close look
    at it, as you will receive hard copies by usps mail in few days.

    Attachment: E-Loan-Appraiser-Results.pif

  • From: (spoofed) Wells Fargo Accounting <>
    Subject: Re: Wells Fargo Bank New Business Account Application - ID# 4489
    Message body:

    Dear Sir,

    Thank you for your online application for a Business Account with Wells Fargo. We appreciate your interest in banking with us.

    In order to open a Business Account, we must receive specific credit information that is verifiable. Because Wells Fargo has no locations in your state, we are unable to confirm the credit information in your application. Consequently, we regret to say that we cannot open an account for your business at this time.

    Attached are your Wells Fargo Application and your Social Security File.


    Sherli Chin
    Business Resource Center Services
    Wells Fargo Bank


  • From: (spoofed) "Loan Department" <>
    Subject: Re: Your balance application
    Message body:

    Dear sir!

    Thank you for your online application for a Home Equity Loan. In order to be
    approved for any loan application we pull your Balance Profile and Chexsystems
    information, which didn't satisfy our minimum needs. Consequently, we regret
    to say that we cannot approve you for Home Equity Loan at this time. *Attached
    are copy of your Balance Profile and Your Application that you submitted with
    us. Please take a close look at it you will receive hard copy by mail withing
    next few days.

  • From: (spoofed) Brian Spencer []
    Subject: fraud report
    Message body:

    Dear Sir!

    We are sorry to report that your bank account has been
    temporarily closed cause of explicit fraud activity. We are about
    to report to the police about this incident and they.ll carefully
    investigate this matter. If you.ll be found guilty, your can be
    charged up to $57,183.
    You can find all the details about this incident in the attached
    file and if you still have any questions until the police start
    investigation, please contact us as soon as possible. Sir, fraud
    activity is prohibited by the US legislation and you must note down
    that from now on your every step is being carefully traced down.
    So if you don.t want any other incidents to take place, wait for
    the end of this investigation or contact us. You can find our email
    and phone number in the attached file(password - MarH3Jl4).

    Faithfully yours, Brian Spencer (Chief Manager)


When Downloader.Berbew runs, it does the following:
    1. Downloads Backdoor.Berbew from a remote server and saves it to %System%. The server from where the file is downloaded may vary, and one location we have seen is The file name in %syste% may also vary. An example of one we have seen is rtdx32.exe.

      Note: %System% is a variable. The Trojan locates the System folder and saves the downloaded Backdoor 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).

    2. Runs Backdoor.Berbew.


    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.

    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 as Downloader.Berbew or Backdoor.Berbew.

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

    1. Disabling 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. Updating 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. Scanning for and deleting the infected files
    1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
    2. Run a full system scan.
    3. If any files are detected as infected with Downloader.Berbew or Backdoor.Berbew, click Delete.

    Writeup By: Sergei Shevchenko