Discovered: April 20, 2004
Updated: February 13, 2007 12:21:39 PM
Also Known As: WORM_MIMAIL.V [Trend], W32/Mimail-V [Sophos], JS.Mimail.V [Computer Associat
Type: Worm
Systems Affected: Windows


W32.Opasa@mm is a mass-mailing worm that:

  • Sends itself to the email addresses that it finds on an infected computer
  • Terminates processes and services, including various security programs
  • Attempts to connect to various IRC servers to wait for additional commands from an attacker.

The email contains a .zip attachment, and the Subject line varies.




Antivirus Protection Dates

  • Initial Rapid Release version April 20, 2004
  • Latest Rapid Release version August 08, 2016 revision 023
  • Initial Daily Certified version April 20, 2004
  • Latest Daily Certified version August 09, 2016 revision 001
  • Initial Weekly Certified release date April 20, 2004

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

Writeup By: Robert X Wang

Discovered: April 20, 2004
Updated: February 13, 2007 12:21:39 PM
Also Known As: WORM_MIMAIL.V [Trend], W32/Mimail-V [Sophos], JS.Mimail.V [Computer Associat
Type: Worm
Systems Affected: Windows


When W32.Opasa@mm is executed, it does the following:

  1. Attempts to end, and then delete any running services that have names containing predetermined strings.


    Note: For a complete list of the predetermined strings, see the "Service Strings" section at the end of this "Technical Details" section.

  2. Attempts to end any running processes that have names containing the predetermined strings mentioned in the "Service Strings" section.

  3. Registers itself as a service.

  4. Creates a random Mutex based on the operating system, so that only one instance of the worm executes.

  5. If the worm was not executed from the %System% folder, it will copy itself to %System%\<random_filename>.exe.


    Note: %System% is a variable. The worm 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).

  6. Creates a randomly named .html or .folder file in the %System% folder.

  7. Adds the value:

    "<Random_name>"="%System%\<random_filename>.exe"

    to the following registry keys:
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
      RunOnce
    • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
      RunOnceEx

  8. Copies itself as the following files:
    • Microsoft Office 2004 downloader.exe
    • WinRar 2004.exe
    • WinZip 2004.exe
    • WinRar 3.30.exe
    • All Windows Service Packs.exe
    • Windows 2003 all service packs.exe
    • Zone Alarm 2004 firewall.exe
    • Kaspersky Anti-Hacker 2004.exe
    • Kaspersky Antivirus 2004 downloader.exe
    • World Trade Center Photos.exe
    • World Trade Center.exe
    • Website Hacker.exe
    • Keylogger.exe
    • AOL Password Cracker.exe
    • ICQ Hacker.exe
    • AOL Instant Messenger (AIM) Hacker.exe
    • MSN Password Cracker.exe
    • Microsoft Windows KeyGen.exe
    • Microsoft Office KeyGen.exe
    • Outlook Password Cracker.exe
    • Windows 9x_nt_xp_2k Password Hacker.exe
    • Last Exploits.exe
    • Serials collection 2004.exe
    • ICQ Cracker.exe
    • Hotmail Cracker.exe
    • Hotmail Hacker.exe
    • Yahoo Hacker.exe
    • Yahoo Cracker.exe
    • FTP Cracker.exe
    • Password Cracker.exe
    • Windows 2003 full downloader.exe
    • Email Cracker.exe
    • Windows Longhorn downloader.exe
    • Last Porn Collection.exeAll stars porn collection.exe
    • 2004 Child Porn.exe
    • Britney Spears mp3.exe
    • Britney Naked.exe
    • Britney Porn.exe
    • Britney Spears.exe

      if any of the following folders are present:
    • C:\Program Files\WinMX\Shared
    • C:\Program Files\Tesla\Files
    • C:\Program Files\LimeWire\Shared
    • C:\Program Files\Morpheus\My Shared Folder
    • C:\Program Files\eMule\Incoming
    • C:\Program Files\eDonkey2000\Incoming
    • C:\Program Files\Bearshare\Shared
    • C:\Program Files\Grokster\My Grokster
    • C:\Program Files\ICQ\Shared Folder
    • C:\Program Files\Kazaa Lite K++\My Shared Folder
    • C:\Program Files\Kazaa Lite\My Shared Folder
    • C:\Program Files\Kazaa\My Shared Folder\

  9. Listens on TCP port 6667 and waits for an attacker to send a URL. When the worm receives a URL, it downloads a file as C:\<random_name>.exe, and then executes it.

  10. Starts an infinite loop in which the worm ends the services and processes and updates the registry.

  11. Attempts to connect to an IRC server, and then waits for the commands from an attacker.

  12. Uses rootkit technology to hide itself from other running processes. The worm does this by attempting to remove itself from the PID list used in Windows NT/2000/XP.

  13. Drops a text file named xxxx.txt in the folder in which the worm is executed.


    Note: This file is not malicious, and therefore Symantec antivirus products will not detected it.

  14. Scans C:\Program Files and all the folders listed in HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\Shell Folders. It also retrieves email addresses from any .wab files found.

  15. Emails itself to all the email addresses that it finds.

    The email message has the following characteristics:

    Subject:
    A randomly selected combination of the following items: [First][Second][Third][Fourth][Fifth]
    • [First]
      Re:
      Re[2]:
    • [Second]
      your
      important
      very important
    • [Third]
      request
      file
      document
      bill
      payment options
      payment details
      details
      account details
      info
      information
    • [Fourth]
      successfully
    • [Fifth]
      changed
      corrected
      modified

      For example, a possible complete subject line is "Re:your account details successfully changed."


      Body:
      A randomly selected combination of the following 15 items:
    • [First]
      hi!
      hello!
      hi there!
      hello there!
    • [Second]
      this important
      very important
    • [Third]
      text
      word
      excel
      ms word
      ms excel
      microsoft word
      microsoft excel
      html
    • [Fourth]
      file
      document
      message
      files
      documents
      messages
    • [Fifth]
      cannot be
      could not be
      couldn't be
    • [Sixth]
      represented
      delivered
      interpreted
    • [Seventh]
      as
    • [Eighth]
      plain
      simple
      pure
    • [Ninth]
      text
      message
    • [Tenth]
      and
      and that's why
      and thats why
    • [Eleventh]
      i have sent
      i've sent
      we have sent
      we've sent
      our administrator has sent
      my network administrator has sent
    • [Twelvth]
      it
      this file
      this document
      this message
    • [Thirteenth]
      as
    • [Fourteenth]
      binary
      archived
      compressed
    • [Fifteenth]
      file!
      attachment!
      message!

      For example, a possible message body could be:

      "hi there!
      this important html messages cannot be represented as plain text and that's why i have sent it as compressed attachment! "

      Attachment:
      An .html file with a random file name or a .zip archive containing the .html file.


      Note: If the worm finds the WinZIP program on an infected computer, it will use it to compress the .html file.


Service Strings
The worm uses the following list of strings when scanning the running services of an infected computer:
  • _avp
  • _avp32
  • _avpcc
  • _avpm
  • _findviru
  • ackwin32
  • advxdwin
  • agentsvr
  • agentw
  • ahnsd
  • alerter
  • alertsvc
  • alogserv
  • amon
  • amon9x
  • anti-trojan
  • antivirus
  • ants
  • apimonitor
  • aplica32
  • apvxdwin
  • atcon
  • atguard
  • atro55en
  • atupdater
  • atwatch
  • aupdate
  • autodown
  • autotrace
  • autoupdate
  • avconsol
  • ave32
  • avgcc32
  • avgctrl
  • avgserv
  • avgserv9
  • avgw
  • avkpop
  • avkserv
  • avkservice
  • avkwcl9
  • avkwctl9
  • avnt
  • avp32
  • avpcc
  • avpdos32
  • avpexec
  • avpinst
  • avpm
  • avpmon
  • avpnt
  • avptc32
  • avpupd
  • avrescue
  • avsched32
  • avsynmgr
  • avwin95
  • avwinnt
  • avwupd32
  • avxmonitor9x
  • avxmonitornt
  • avxquar
  • avxw
  • azonealarm
  • bbeagle.exe
  • bd_professional
  • bidef
  • bidserver
  • bipcp
  • bipcpevalsetup
  • bisp
  • blackd
  • blackice
  • bootwarn
  • borg2
  • bs120
  • ccapp
  • ccevtmgr
  • ccpxysvc
  • ccsetmgr
  • ccshtdwn
  • cdp
  • cfgwiz
  • cfiadmin
  • cfiaudit
  • cfind
  • cfinet
  • cfinet32
  • claw95
  • claw95cf
  • claw95ct
  • clean
  • cleaner
  • cleaner3
  • cleanpc
  • cmgrdian
  • cmon016
  • connectionmonitor
  • cpd
  • cpdclnt
  • cpf9x206
  • cpfnt206
  • csinject
  • csinsm32
  • css1631
  • ctrl
  • cwnb181
  • cwntdwmo
  • defalert
  • defscangui
  • defwatch
  • deputy
  • direct.exe
  • dllhost
  • doors
  • dpf
  • drwatson
  • drweb32
  • dv95
  • dv95_o
  • dvp95
  • dvp95_0
  • ecengine
  • edi
  • efinet32
  • efpeadm
  • ent
  • esafe
  • escanh95
  • escanhnt
  • escanv95
  • fvprotect.exe
  • gigabit.exe
  • go54o.exe
  • gouday.exe
  • i1ru54n4.exe
  • iamserv
  • iamstats
  • ibmasn
  • ibmavsp
  • icload95
  • icloadnt
  • icmon
  • icmoon
  • icssuppnt
  • icsupp
  • icsupp95
  • icsuppnt
  • iface
  • ifw2000
  • ii5nj4.exe
  • iomon98
  • iparmor
  • iris
  • irun4.exe
  • isrv95
  • jammer
  • jed
  • jedi
  • kavlite40eng
  • kavpers40eng
  • kerio-pf-213-en-win
  • kerio-wrl-421-en-win
  • kerio-wrp-421-en-win
  • killprocesssetup161
  • kpf
  • kpfw32
  • ldnetmon
  • ldpro
  • ldpromenu
  • ldscan
  • localnet
  • lockdown
  • lockdown2000
  • lookout
  • lsetup
  • luall
  • luau
  • lucomserver
  • luinit
  • luspt
  • mcagent
  • mcmnhdlr
  • mcshield
  • mctool
  • mcupdate
  • mcvsrte
  • mcvsshld
  • mfw2en
  • mfweng3.02d30
  • mgavrtcl
  • mgavrte
  • mghtml
  • mgui
  • minilog
  • monitor
  • monsys32
  • monsysnt
  • monwow
  • moolive
  • mpfagent
  • mpfservice
  • mpftray
  • mrflux
  • msblast
  • msconfig
  • msinfo32
  • mspatch
  • mssmmc32
  • mu0311ad
  • mwatch
  • mxtask
  • n32scan
  • n32scanw
  • nai_vs_stat
  • nav32_loader
  • nav80try
  • navap
  • navapsvc
  • navapw32
  • navauto-protect
  • navdx
  • naveng
  • navengnavex15
  • navex15
  • navlu32
  • navnt
  • navrunr
  • navsched
  • navstub
  • navw
  • navw32
  • navwnt
  • nc2000
  • ncinst4
  • ndd32
  • neomonitor
  • neowatchlog
  • netarmor
  • netinfo
  • netmon
  • netscanpro
  • netspyhunter-1.2
  • netstat
  • netutils
  • nisserv
  • nisum
  • nmain
  • nod32
  • normist
  • norton_internet_secu_3.0_407
  • notstart
  • npf40_tw_98_nt_me_2k
  • npfmessenger
  • nprotect
  • npscheck
  • npssvc
  • nsched32
  • nsplugin
  • ntrtscan
  • ntvdm
  • ntxconfig
  • nui
  • nupdate
  • nupgrade
  • nvapsvc
  • nvarch16
  • nvc95
  • nvlaunch
  • nvsvc32
  • nwinst4
  • nwservice
  • nwtool16
  • offguard
  • ogrc
  • ostronet
  • outpost
  • outpostinstall
  • outpostproinstall
  • padmin
  • panixk
  • pathping
  • pavcl
  • pavproxy
  • pavsched
  • pavw
  • pcc2002s902
  • pcc2k_76_1436
  • pccclient
  • pccguide
  • pcciomon
  • pccmain
  • pccntmon
  • pccpfw
  • pccwin97
  • pccwin98
  • pcdsetup
  • pcfwallicon
  • pcip10117_0
  • pcscan
  • pcscanpdsetup
  • penis32
  • periscope
  • persfw
  • perswf
  • pf2
  • pfwadmin
  • ping
  • pingscan
  • platin
  • pop3trap
  • poproxy
  • popscan
  • portdetective
  • portmonitor
  • ppinupdt
  • pptbc
  • ppvstop
  • processmonitor
  • procexplorerv1.0
  • programauditor
  • proport
  • protectx
  • pspf
  • purge
  • pview
  • pview95
  • qconsole
  • qserver
  • rapapp
  • rate.exe
  • rav
  • rav7
  • rav7win
  • rav8win32eng
  • realmon
  • regedit
  • rescue
  • rescue32
  • route
  • routemon
  • rrguard
  • rshell
  • rtvscn95
  • rulaunch
  • safeweb
  • sbserv
  • scan32
  • scan95
  • scanpm
  • schedapp
  • scrscan
  • scvhosl
  • serv95
  • setup_flowprotector_us
  • setupvameeval
  • sfc
  • sgssfw32
  • sharedaccess
  • shellspyinstall
  • shn
  • smc
  • smss
  • sofi
  • spf
  • sphinx
  • spider
  • spyxx
  • srate.exe
  • srwatch
  • ss3edit
  • ssate.exe
  • st2
  • supftrl
  • supporter5
  • sweep
  • sweep95
  • sweepnet
  • sweepsrv.sys
  • swnetsup
  • symproxysvc
  • symtray
  • sysdoc32
  • sysedit
  • syshelp
  • sysmon.exe
  • syswrun4x.exe
  • taskmon
  • taumon
  • tauscan
  • tbscan
  • tca
  • tcm
  • tcpsvs32
  • tds2
  • tds2-98
  • tds2-nt
  • tds-3
  • tfak
  • tfak5
  • tftpd
  • tgbob
  • titanin
  • titaninxp
  • tmntsrv
  • tracerpt
  • tracert
  • trjscan
  • trjsetup
  • trojantrap3
  • undoboot
  • update
  • vbcmserv
  • vbcons
  • vbust
  • vbwin9x
  • vbwinntw
  • vccmserv
  • vcleaner
  • vcontrol
  • vcsetup
  • vet32
  • vet95
  • vet98
  • vettray
  • vfsetup
  • vir-help
  • virusmdpersonalfirewall
  • vnlan300
  • vnpc3000
  • vpc32
  • vpc42
  • vpfw30s
  • vptray
  • vscan
  • vscan40
  • vscenu6.02d30
  • vsched
  • vsecomr
  • vshwin32
  • vsisetup
  • vsmain
  • vsmon
  • vsscan40
  • vsstat
  • vswin9xe
  • vswinntse
  • vswinperse
  • vvstat
  • w32dsm89
  • w9x
  • watch
  • watchdog
  • webscan
  • webscanx
  • webtrap
  • wfindv32
  • wgfe95
  • whoswatchingme
  • wimmun32
  • wingate
  • winhlpp32
  • wink
  • winmgm32
  • winppr32
  • winrecon
  • winroute
  • winservices
  • winsfcm
  • winsys.exe
  • winupd.exe
  • wnt
  • wradmin
  • wrctrl
  • wsbgate
  • wyvernworksfirewall
  • xpf202en
  • zapro
  • zapsetup3001
  • zatutor
  • zatutorzauinst
  • zauinst
  • zonalarm
  • zonalm2601
  • zonealarm


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: Robert X Wang

Discovered: April 20, 2004
Updated: February 13, 2007 12:21:39 PM
Also Known As: WORM_MIMAIL.V [Trend], W32/Mimail-V [Sophos], JS.Mimail.V [Computer Associat
Type: Worm
Systems Affected: Windows


Removal using the W32.Opasa@mm Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of W32.Opasa@mm. Try this tool first, as it is the easiest way to remove this threat.

Manual 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 W32.Opasa@mm.
  5. Reverse the changes made to the registry.
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:
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 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.
  2. Run a full system scan.
  3. If any files are detected as infected with W32.Opasa@mm, click Delete.

5. To reverse the changes made to the registry


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.
  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 each of the following keys:
    • HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run
    • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
    • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
      RunOnce
    • HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\
      RunOnceEx

  4. In the right pane, delete the value:

    "<Random_name>"="%System%\<random_filename>.exe"

  5. Exit the Registry Editor.

  6. 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."


Writeup By: Robert X Wang