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Discovered: July 04, 2005
Updated: February 13, 2007 12:41:43 PM
Also Known As: Backdoor.Win32.Surila.t [Kaspe, W32/Mydoom.gen@MM [McAfee], W32/MyDoom-Gen [Sophos], WORM_MYDOOM.BG [Trend Micro]
Type: Worm
Systems Affected: Windows

W32.Bobax.AA@mm is a mass-mailing worm that sends itself to addresses gathered from the compromised computer and from search results on www.google.com and www.accoona.com. It also operates as a covert proxy.

Note: Virus definitions dated July 31st, 2005 or earlier may detect this threat as W32.Bobax.AA.

Antivirus Protection Dates

  • Initial Rapid Release version July 04, 2005
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version July 04, 2005
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date July 06, 2005

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

Writeup By: Costin Ionescu

Discovered: July 04, 2005
Updated: February 13, 2007 12:41:43 PM
Also Known As: Backdoor.Win32.Surila.t [Kaspe, W32/Mydoom.gen@MM [McAfee], W32/MyDoom-Gen [Sophos], WORM_MYDOOM.BG [Trend Micro]
Type: Worm
Systems Affected: Windows

When W32.Bobax.AA@mm is executed, it performs the following actions:

  1. Checks the current date on the compromised computer. The virus uninstalls itself, if the date is later than September 15th, 2005, 12:05 a.m.

  2. Creates the mutex named "aaqeiuhasdkjhd", so that only one instance of the threat runs on the compromised computer.

  3. Ends the following processes, some of which may be security-related:

    • AVWUPD32.EXE
    • b055262c.dll
    • backdoor.rbot.gen.exe
    • backdoor.rbot.gen_(17).exe
    • dailin.exe
    • GfxAcc.exe
    • ICSUPP95.EXE
    • Lien Van de Kelderrr.exe
    • msnmsgr.exe
    • msssss.exe
    • rasmngr.exe
    • RAVMOND.exe
    • RB.EXE
    • Systra.exe
    • taskmanagr.exe
    • VisualGuard.exe
    • wfdmgr.exe
    • WIN32.EXE
    • WIN32US.EXE
    • WINPPR32.EXE
    • winshost.exe
    • WINSSK32.EXE
    • WINTSK32.EXE
    • WNAD.EXE
    • WNT.EXE
    • wowpos32.exe
    • wuamga.exe
    • wuamgrd.exe
    • XPF202EN.EXE
    • ZAPSETUP3001.EXE
    • ZONALM2601.EXE
    • _AVP32.EXE
    • _AVPCC.EXE
    • _AVPM.EXE

  4. Creates the following files:
    • %Windir%\services.exe
    • %Windir%\msdefr.exe
    • c:\Autorun.inf

      Note: %Windir% is a variable that refers to the Windows installation folder. By default, this is C:\Windows or C:\Winnt.

  5. Adds the value:

    "RPCserv32g" = "%Windir%\services.exe"

    to the registry subkey:


    so that the risk runs every time Windows starts.

  6. Adds the value:

    "fdfg" = [NUMBER]

    to the registry subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer

    to mark its current mass-mailing stage.

  7. Searches for email addresses in the Windows Address Book, Internet Explorer's cache folder, and the %Temp% folder in order to send itself through email.

    Note: %Temp% is a variable that refers to the Windows temporary folder. By default, this is C:\Windows\TEMP (Windows 95/98/Me/XP) or C:\WINNT\Temp (Windows NT/2000).

  8. Obtains more email addresses by generating search queries using a GET request to www.google.com and www.accoona.com.

  9. Varies the format of the malicious email from one instance to another, as it uses various social engineering techniques to create the following email characteristics:

    One of the following:

    • [BLANK]
    • RE:
    • Accounts department
    • Ahtung!
    • Camila
    • Daily activity report
    • Ello!
    • Flayers among us
    • Freedom for everyone
    • From Hair-cutter
    • From me
    • Greet the day
    • Hardware devices price-list
    • Hello my friend
    • Hi!
    • Jenny
    • Jessica
    • Looking for the report
    • Maria
    • Melissa
    • Monthly incomings summary
    • New Price-list
    • Price
    • Price list
    • Price-list
    • Pricelist
    • Proclivity to servitude
    • Registration confirmation
    • The account
    • The employee
    • The summary
    • USA government abolishes the capital punishment
    • Weekly activity report
    • Well...
    • You are dismissed
    • You really love me? he he
    • Your Message could not be delivered
    • Message could not be delivered
    • Mail System Error /- Returned Mail
    • Delivery reports about your e/-mail
    • Returned mail: see transcript for details
    • Returned mail: Data format error
    • hello
    • hi
    • error
    • status
    • test
    • report
    • delivery
    • failed

      The worm uses a complex algorithm to generate a wide range of message bodies. Three formats have been reported and are described below. The possible variant email characteristics are separated with a pipe symbol within each format:

      Format 1:
      [REPORT 1] | [REPORT 2]


    • Dear user [ACCOUNT] of [DOMAIN],
      mail system administrator | mail server administrator | administration
      of [DOMAIN] would like to
      inform you | inform you that | let you know that | let you know the following

      [REPORT 1]:

    • We have
      detected | found | received rep [REMOVED] ring
      this | the last | the recent

      [REPORT 2]:

    • We suspect that
      Probably, | Most likely | Obviously,
      your computer
      has been | was
      compromised | infected | infected by a recent virus
      and now
      runs a | contains a
      trojan | trojaned | hidden
      proxy server


    • Please | We recommend | We recommend that you | We recommend you to
      follow our | follow the | follow
      instruction | instructions
      in the
      attachment | attached file | attached text file
      in order to keep your computer safe.
      Virtually yours | Sincerely yours | Best wishes | Best regards | Have a  nice day
      [DOMAIN] user team | [DOMAIN] tehnical team | [DOMAIN] support team | The [DOMAIN] support team


    • The | This | Your
      message was
      undeliverable | not delivered
      due to the following reason(s):

      One of the following:

    • Your message
      was not | could not be
      delivered because the destination
      computer | server
      was not reachable | was unreachable
      within the allowed queue period. The amount of time
      a message is queued before it is returned depends on local configura-
      tion parameters.
    • Most likely there is a network problem that prevented delivery, but
      it is also possible that the computer is turned off, or does not
      have a mail system running right now.
    • Your message
      was not | could not be
      delivered within 3 days:
      Mail server | Host
      [RANDOM IP ADDRESS] is not responding.
    • The following recipients did not receive this message: [EMAIL]
    • The following recipients could not receive this message: [EMAIL]

      [FATAL ERROR]:

    • The original message was received at [DATE] from [RANDOM IP ADDRESS]
      ----- The following addresses had permanent fatal errors -----

      Format 2:
      One of the following:

    • Cya
    • Empty
    • Everything inside the attach
    • Look it through
    • Subj
    • Request
    • Response

      Format 3:

      One of the following:

    • Attached some pics that i found
    • Check this out :-)
    • Hello,
    • I was going through my album, and look what I found..
    • Long time! Check this out!
    • Osama Bin Laden Captured.
    • Remember this?
    • Saddam Hussein - Attempted Escape, Shot dead
    • Secret!
    • Testing

      One of the following:

    • +++ Attachment: No Virus found
    • +++ F-Secure AntiVirus - You are protected
    • +++ Norman AntiVirus - You are protected
    • +++ Norton AntiVirus - You are protected
    • +++ Panda AntiVirus - You are protected
    • +++ www.f-secure.com
    • +++ www.norman.com
    • +++ www.pandasoftware.com
    • +++ www.symantec.com
    • MessageLabs AntiVirus /- www.messagelabs.com
    • Bitdefender AntiVirus /- www.bitdefender.com
    • MC/-Afee AntiVirus /- www.mcafee.com
    • Kaspersky AntiVirus /- www.kaspersky.com
    • Panda AntiVirus /- www.pandasoftware.com
    • Norman AntiVirus /- www.norman.com
    • F/-Secure AntiVirus /- www.f/-secure.com
    • Norton AntiVirus /- www.symantec.de

      The worm constructs the attachment name in the following format:

      One of the following:

    • bush
    • funny
    • joke
    • pics
    • secret
    • price2005
    • joke
    • work
    • job
    • test
    • account_info
    • billing_info
    • payment
    • [4 to 7 RANDOM CHARACTERS]

      One of the following:

    • doc
    • txt
    • info

      One of the following:

    • pif
    • scr
    • exe

  10. Performs a denial of service attack on www.rit.edu by sending large HTTP requests of approximately 70KB.

  11. Opens a back door with proxy functionality on a random port.

  12. Attempts to connect to the following IP addresses using the specified ports:

    • (Port 4242)
    • (Port 4242)
    • (Port 4661)
    • (Port 4242)
    • (Port 4661)
    • (Port 4242)
    • (Port 4661)

  13. The worm may also attempt to download several files from the following Web sites:

    • [http://]www.aartanridge.org.uk/[REMOVED]/adnim.gif
    • [http://]www.eastcoastchoons.co.uk/[REMOVED]/DSCN2747.JPG
    • [http://]www.foxalpha.com/[REMOVED]/contraste.jpg
    • [http://]www.ribaforada.net/[REMOVED]/genteite.gif
    • [http://]www.sundayriders.co.uk/[REMOVED]/pixel_blue.gif
    • [http://]www.yamamizuryu.org/[REMOVED]/images/HotNinjaKunoichmsi.gif
    • [http://]www.foxalpha.com/[REMOVED]/contraste.jpg
    • [http://]www.hooping.org/[REMOVED]/DSCN0622.JPG
    • [http://]www.imogenheap.co.uk/[REMOVED]/Applepiona.jpg
    • [http://]www.lancer.com.ru/[REMOVED]/osoga.jpg
    • [http://]www.newgenerationcomics.net/[REMOVED]/NGCbanren.jpg

      Note: At the time of writing, several of the links were not functioning while others may contain copies of Backdoor.Nemog.D.


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: Costin Ionescu

Discovered: July 04, 2005
Updated: February 13, 2007 12:41:43 PM
Also Known As: Backdoor.Win32.Surila.t [Kaspe, W32/Mydoom.gen@MM [McAfee], W32/MyDoom-Gen [Sophos], WORM_MYDOOM.BG [Trend Micro]
Type: Worm
Systems Affected: Windows

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:
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.
  2. Run a full system scan.
  3. If any files are detected, click Delete.
  4. Navigate to the root of drive C: and delete the file Autorun.inf.

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:


  5. In the right pane, delete the value:

    "RPCserv32g" = "%Windir%\services.exe"

  6. Navigate to the subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Internet Explorer

  7. In the right pane, delete the value:

    "fdfg" = [number]

  8. Exit the Registry Editor.

Writeup By: Costin Ionescu