Discovered: April 16, 2005
Updated: February 13, 2007 12:37:13 PM
Also Known As: Win32.Glieder.{W, Y} [Computer Associates], Email-Worm.Win32.Bagle.{bj, bk} [Kaspersky Lab], W32/Bagle.dll.gen [McAfee], W32/Bagle.gen@MM [McAfee], W32/Bagle.bs.{dr, gen} [McAfee], Troj/BagDl-Gen [Sophos], Troj/BagleDl-N [Sophos], TROJ_BAGLE.BH [Trend Micro]
Type: Trojan Horse
Systems Affected: Windows


Trojan.Tooso.H is a Trojan horse that interferes with the operation of security software by terminating processes, stopping services, removing registry entries, and deleting files.

Trojan.Tooso.H attempts to download a copy of Trojan.Tooso.F .



This Trojan may arrive in an email with a .zip file attachment. The file inside the attachment may be 1.exe.

Reinstalling Services
You may also wish to re-enable services that were disabled by the threat. In the services window (in "Control Panel" for Windows 9x and in "Control Panel\Administrative Tools" for Windows 2000 and Windows XP), find the services that have been disabled, double click on them, and reset the "startup type" value from the drop down menu.

Antivirus Protection Dates

  • Initial Rapid Release version April 16, 2005
  • Latest Rapid Release version January 15, 2018 revision 020
  • Initial Daily Certified version April 16, 2005
  • Latest Daily Certified version January 15, 2018 revision 024
  • Initial Weekly Certified release date April 16, 2005

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

Writeup By: John Park

Discovered: April 16, 2005
Updated: February 13, 2007 12:37:13 PM
Also Known As: Win32.Glieder.{W, Y} [Computer Associates], Email-Worm.Win32.Bagle.{bj, bk} [Kaspersky Lab], W32/Bagle.dll.gen [McAfee], W32/Bagle.gen@MM [McAfee], W32/Bagle.bs.{dr, gen} [McAfee], Troj/BagDl-Gen [Sophos], Troj/BagleDl-N [Sophos], TROJ_BAGLE.BH [Trend Micro]
Type: Trojan Horse
Systems Affected: Windows


When Trojan.Tooso.H is executed, it performs the following actions:

  1. Copies itself as %System%\winshost.exe

    Note: %System% is a variable that refers to the System folder. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  2. Drops the following file:

    %System%\wiwshost.exe

    Note: %System% is a variable that refers to the System folder. By default this is C:\Windows\System (Windows 95/98/Me), C:\Winnt\System32 (Windows NT/2000), or C:\Windows\System32 (Windows XP).

  3. Adds the value:

    "winshost.exe" = "%System%\winshost.exe"

    to the registry subkeys:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run

    so that Trojan.Tooso.H runs every time Windows starts.

  4. Attempts to find the explorer.exe process and inject wiwshost.exe into it. All subsequent actions are taken by wiwshost.exe but appear to be taken by explorer.exe.

  5. Starts a thread that disables services with the following names:

    • Ahnlab task Scheduler
    • alerter
    • AlertManger
    • AVExch32Service
    • avg7alrt
    • avg7updsvc
    • AvgCore
    • AvgFsh
    • AvgServ
    • AVPCC
    • avpcc
    • AVUPDService
    • AvxIni
    • awhost32
    • backweb client-4476822
    • backweb client - 4476822
    • BackWeb Client - 7681197
    • BlackICE
    • CAISafe
    • ccEvtMgr
    • ccPwdSvc
    • ccSetMgr
    • ccSetMgr.exe
    • DefWatch
    • dvpapi
    • dvpinit
    • F-Secure Gatekeeper Handler Starter
    • fsbwsys
    • FSDFWD
    • fsdfwd
    • FSMA
    • KAVMonitorService
    • kavsvc
    • KLBLMain
    • McAfee Firewall
    • McAfeeFramework
    • McShield
    • McTaskManager
    • mcupdmgr.exe
    • MCVSRte
    • MonSvcNT
    • navapsvc
    • Network Associates Log Service
    • NISSERV
    • NISUM
    • NOD32ControlCenter
    • NOD32Service
    • Norman NJeeves
    • Norman ZANDA
    • Norton Antivirus Server
    • NPFMntor
    • NProtectService
    • NSCTOP
    • nvcoas
    • NVCScheduler
    • nwclntc
    • nwclntd
    • nwclnte
    • nwclntf
    • nwclntg
    • nwclnth
    • NWService
    • Outbreak Manager
    • Outpost Firewall
    • OutpostFirewall
    • PASSRV
    • PAVFNSVR
    • Pavkre
    • PavProt
    • PavPrSrv
    • PAVSRV
    • PCCPFW
    • PersFW
    • PREVSRV
    • PSIMSVC
    • ravmon8
    • SAVFMSE
    • SAVScan
    • SBService
    • schscnt
    • sharedaccess
    • SharedAcces
    • SmcService
    • SNDSrvc
    • SPBBCSvc
    • SweepNet
    • SWEEPSRV.SYS
    • Symantec AntiVirus Client
    • Symantec Core LC
    • Tmntsrv
    • V3MonNT
    • V3MonSvc
    • VexiraAntivirus
    • VisNetic AntiVirus Plug-in
    • vsmon
    • wuauserv
    • XCOMM

  6. Attempts to delete the following registry entries, which prevent security-related programs from running when Windows starts:

    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\McAfee.InstantUpdate.Monitor
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\APVXDWIN
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\avg7_cc
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\avg7_emc
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\ccApp
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\KAV50
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\McAfee Guardian
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\NAV CfgWiz
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\SSC_UserPrompt
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Symantec NetDriver Monitor
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run\Zone Labs Client
    HKEY_LOCAL_MACHINE\SOFTWARE\Agnitum
    HKEY_LOCAL_MACHINE\SOFTWARE\KasperskyLab
    HKEY_LOCAL_MACHINE\SOFTWARE\McAfee
    HKEY_LOCAL_MACHINE\SOFTWARE\Panda Software
    HKEY_LOCAL_MACHINE\SOFTWARE\Symantec
    HKEY_LOCAL_MACHINE\SOFTWARE\Zone Labs

  7. Starts a thread that attempts to delete all instances of files with the following names from all fixed drives:

    • a5v.dll
    • AUPD1ATE.EXE
    • AUPDATE.EXE
    • av.dll
    • Av1synmgr.exe
    • Avc1onsol.exe
    • Avconsol.exe
    • avg23emc.exe
    • avgc3c.exe
    • avgcc.exe
    • avgemc.exe
    • Avsynmgr.exe
    • C1CSETMGR.EXE
    • c6a5fix.exe
    • cafix.exe
    • CC1EVTMGR.EXE
    • cc1l30.dll
    • ccApp.exe
    • CCEVTMGR.EXE
    • ccl30.dll
    • CCSETMGR.EXE
    • ccv1rtrst.dll
    • ccvrtrst.dll
    • CM1Grdian.exe
    • CMGrdian.exe
    • is5a6fe.exe
    • isafe.exe
    • K2A2V.exe
    • KAV.exe
    • kav12mm.exe
    • kavmm.exe
    • LUAL1L.EXE
    • LUALL.EXE
    • LUI1NSDLL.DLL
    • LUINSDLL.DLL
    • Luup1date.exe
    • Luupdate.exe
    • Mcsh1ield.exe
    • Mcshield.exe
    • mysuperprog.exe
    • NAV1APSVC.EXE
    • NAVAPSVC.EXE
    • NPFM1NTOR.EXE
    • NPFMNTOR.EXE
    • outp1ost.exe
    • outpost.exe
    • RuLa1unch.exe
    • RuLaunch.exe
    • s1ymlcsvc.exe
    • SND1Srvc.exe
    • SNDSrvc.exe
    • SP1BBCSvc.exe
    • SPBBCSvc.exe
    • symlcsvc.exe
    • Up222Date.exe
    • Up2Date.exe
    • ve6tre5dir.dll
    • vetredir.dll
    • Vs1Stat.exe
    • vs6va5ult.dll
    • Vshw1in32.exe
    • Vshwin32.exe
    • VsStat.exe
    • vsvault.dll
    • zatu6tor.exe
    • zatutor.exe
    • zatutor.exe
    • zl5avscan.dll
    • zlavscan.dll
    • zlavscan.dll
    • zlcli6ent.exe
    • zlclient.exe
    • zo3nealarm.exe
    • zonealarm.exe
    • zonealarm.exe

  8. Starts a thread that attempts to stop the following services:

    • SharedAccess
    • wscsvc

  9. Starts a thread that attempts to terminate processes with the following names:

    • ATUPDATER.EXE
    • ATUPDATER.EXE
    • AUPDATE.EXE
    • AUTODOWN.EXE
    • AUTOTRACE.EXE
    • AUTOUPDATE.EXE
    • AVPUPD.EXE
    • AVWUPD32.EXE
    • AVXQUAR.EXE
    • AVXQUAR.EXE
    • CFIAUDIT.EXE
    • DRWEBUPW.EXE
    • ESCANH95.EX
    • ESCANHNT.EXE
    • FIREWALL.EXE
    • ICSSUPPNT.EXE
    • ICSUPP95.EXE
    • LUALL.EXE
    • MCUPDATE.EXE
    • NUPGRADE.EXE
    • NUPGRADE.EXE
    • OUTPOST.EXE
    • UPDATE.EXE
    • UPGRADER.EXE

  10. Starts a thread that attempts to download files from the following domains in the sequence given. The first attempt occurs when the Trojan is launched and subsequent attempts occur at six-hour intervals. The Trojan downloads the file %Windir%\_re_file.exe and runs it. The downloaded file is detected as Trojan.Tooso.F.

    • 21ebuild.com
    • 51.net
    • acsohio.com
    • agria.hu
    • andi.com.vn
    • angham.de
    • ascolfibras.com
    • automobilonline.de
    • bangyan.cn
    • beall-cpa.com
    • bolz.at
    • bs-security.de
    • centrovestecasa.it
    • checkonemedia.nl
    • contentproject.com
    • cz-wanjia.com
    • czwanqing.com
    • czzm.com
    • datanet.huwww.datanet.hu
    • designgong.org
    • dgy.com.cn
    • die-fliesen.de
    • discoteka-funfactory.com
    • dom-invest.com.pl
    • eagle.com.cn
    • eagleclub.com.cn
    • ehc.hu
    • elvis-presley.ch
    • engelhardtgmbh.de
    • externet.hu
    • fahrschule-herb.de
    • fahrschule-lesser.de
    • fermegaroy.com
    • festivalteatrooccidente.com
    • formholz.at
    • fotomax.fi
    • gemtrox.com.tw
    • gepeters.org
    • gimex-messzeuge.de
    • gomyhome.com.tw
    • gymzn.cz
    • hondenservice.be
    • idaf.de
    • .idcs.be
    • .ider.cl
    • inside-tgweb.de
    • izoli.sk
    • .jcm-american.com
    • jeoushinn.com
    • jingjuok.com
    • jue-bo.com
    • kingsley.ch
    • marketvw.com
    • megaserve.net
    • mild.at
    • niko.de
    • nikogmbh.com
    • olva.com.pe
    • on24.ee
    • onlink.net
    • ppm-alliance.de
    • presley.ch
    • renegaderc.com
    • replayu.com
    • sachsenbuecher.de
    • sanjinyuan.com
    • scvanravenswaaij.nl
    • slovanet.sk
    • snsphoto.com
    • societaet.de
    • soeco.org
    • softmajor.ru
    • solt3.org
    • spacium.biz
    • speedcom.home.pl
    • spirit-in-steel.at
    • spoden.de
    • sportnf.com
    • spy.az
    • sqnsolutions.com
    • st-paulus-bonn.dehtdocs
    • stbs.com.hk
    • steripharm.com
    • students.stir.ac.uk
    • subsplanet.com
    • sungodbio.com
    • superbetcs.com
    • sweb.cz
    • sydolo.com
    • szdiheng.com
    • tcicampus.net
    • techni.com.cn
    • tg-sandhausen-basketball.de
    • th-mutan.com
    • thaifast.com
    • thaiventure.com
    • thefunkiest.com
    • thenextstep.tv
    • thetexasoutfitter.com
    • tmhcsd1987.friko.pl
    • toussain.be
    • trago.com.pt
    • travelourway.com
    • trgd.dobrcz.pl
    • triapex.cz
    • triptonic.ch
    • tv-marina.com
    • udc-cassinadepecchi.it
    • universe.sk
    • uspowerchair.com
    • uw.hu
    • vercruyssenelektro.be
    • vet24h.com
    • vinimeloni.com
    • vnn.vn
    • vnrvjiet.ac.in
    • vote2fateh.com
    • vw.press-bank.pl
    • wamba.asn.au
    • wdlp.co.za
    • welchcorp.com
    • wesartproductions.com
    • wilsonscountry.com
    • windstar.pl
    • wise-industries.com
    • witold.pl
    • wombband.com
    • xiantong.net
    • xmpie.com
    • xmtd.com
    • xojc.com
    • yannick-spruyt.be
    • yayadownload.com
    • yesterdays.co.za
    • yshkj.com
    • zakazcd.dp.ua
    • zenesoftware.com
    • zentek.co.za
    • zorbas.az
    • zsbersala.edu.sk

  11. Overwrites the infected computer's hosts file with the following lines to disable access to the following security-related Web sites:

    127.0.0.1 localhost
    127.0.0.1 ad.doubleclick.net
    127.0.0.1 ad.fastclick.net
    127.0.0.1 ads.fastclick.net
    127.0.0.1 ar.atwola.com
    127.0.0.1 atdmt.com
    127.0.0.1 avp.ch
    127.0.0.1 avp.com
    127.0.0.1 avp.ru
    127.0.0.1 awaps.net
    127.0.0.1 banner.fastclick.net
    127.0.0.1 banners.fastclick.net
    127.0.0.1 ca.com
    127.0.0.1 click.atdmt.com
    127.0.0.1 clicks.atdmt.com
    127.0.0.1 dispatch.mcafee.com
    127.0.0.1 download.mcafee.com
    127.0.0.1 download.microsoft.com
    127.0.0.1 downloads.microsoft.com
    127.0.0.1 engine.awaps.net
    127.0.0.1 fastclick.net
    127.0.0.1 f-secure.com
    127.0.0.1 ftp.f-secure.com
    127.0.0.1 ftp.sophos.com
    127.0.0.1 go.microsoft.com
    127.0.0.1 liveupdate.symantec.com
    127.0.0.1 mast.mcafee.com
    127.0.0.1 mcafee.com
    127.0.0.1 media.fastclick.net
    127.0.0.1 msdn.microsoft.com
    127.0.0.1 my-etrust.com
    127.0.0.1 nai.com
    127.0.0.1 networkassociates.com
    127.0.0.1 office.microsoft.com
    127.0.0.1 phx.corporate-ir.net
    127.0.0.1 secure.nai.com
    127.0.0.1 securityresponse.symantec.com
    127.0.0.1 service1.symantec.com
    127.0.0.1 sophos.com
    127.0.0.1 spd.atdmt.com
    127.0.0.1 support.microsoft.com
    127.0.0.1 symantec.com
    127.0.0.1 update.symantec.com
    127.0.0.1 updates.symantec.com
    127.0.0.1 us.mcafee.com
    127.0.0.1 vil.nai.com
    127.0.0.1 viruslist.ru
    127.0.0.1 windowsupdate.microsoft.com
    127.0.0.1 www.avp.ch
    127.0.0.1 www.avp.com
    127.0.0.1 www.avp.ru
    127.0.0.1 www.awaps.net
    127.0.0.1 www.ca.com
    127.0.0.1 www.fastclick.net
    127.0.0.1 www.f-secure.com
    127.0.0.1 www.kaspersky.ru
    127.0.0.1 www.mcafee.com
    127.0.0.1 www.my-etrust.com
    127.0.0.1 www.nai.com
    127.0.0.1 www.networkassociates.com
    127.0.0.1 www.sophos.com
    127.0.0.1 www.symantec.com
    127.0.0.1 www.trendmicro.com
    127.0.0.1 www.viruslist.ru
    127.0.0.1 ftp:/ /ftp.kasperskylab.ru/updates/
    127.0.0.1 ftp:/ /ftp.avp.ch/updates/
    127.0.0.1 http:/ /www.kaspersky.ru/updates/
    127.0.0.1 http:/ /updates1.kaspersky-labs.com/updates/
    127.0.0.1 http:/ /updates3.kaspersky-labs.com/updates/
    127.0.0.1 http:/ /updates4.kaspersky-labs.com/updates/
    127.0.0.1 http:/ /updates2.kaspersky-labs.com/updates/
    127.0.0.1 http:/ /updates5.kaspersky-labs.com/updates/
    127.0.0.1 http:/ /downloads1.kaspersky-labs.com/updates/
    127.0.0.1 http:/ /www.kaspersky-labs.com/updates/
    127.0.0.1 ftp:/ /updates3.kaspersky-labs.com/updates/
    127.0.0.1 ftp:/ /downloads1.kaspersky-labs.com/updates/
    127.0.0.1 www3.ca.com
    127.0.0.1 ids.kaspersky-labs.com
    127.0.0.1 downloads2.kaspersky-labs.com
    127.0.0.1 downloads1.kaspersky-labs.com
    127.0.0.1 downloads3.kaspersky-labs.com
    127.0.0.1 downloads4.kaspersky-labs.com
    127.0.0.1 liveupdate.symantecliveupdate.com
    127.0.0.1 liveupdate.symantec.com
    127.0.0.1 update.symantec.com
    127.0.0.1 download.mcafee.com
    127.0.0.1 www.symantec.com
    127.0.0.1 securityresponse.symantec.com
    127.0.0.1 symantec.com
    127.0.0.1 www.sophos.com
    127.0.0.1 sophos.com
    127.0.0.1 www.mcafee.com
    127.0.0.1 mcafee.com
    127.0.0.1 liveupdate.symantecliveupdate.com
    127.0.0.1 www.viruslist.com
    127.0.0.1 viruslist.com
    127.0.0.1 f-secure.com
    127.0.0.1 www.f-secure.com
    127.0.0.1 kaspersky.com
    127.0.0.1 kaspersky-labs.com
    127.0.0.1 www.avp.com
    127.0.0.1 www.kaspersky.com
    127.0.0.1 avp.com
    127.0.0.1 www.networkassociates.com
    127.0.0.1 networkassociates.com
    127.0.0.1 www.ca.com
    127.0.0.1 ca.com
    127.0.0.1 mast.mcafee.com
    127.0.0.1 my-etrust.com
    127.0.0.1 www.my-etrust.com
    127.0.0.1 download.mcafee.com
    127.0.0.1 dispatch.mcafee.com
    127.0.0.1 secure.nai.com
    127.0.0.1 nai.com
    127.0.0.1 www.nai.com
    127.0.0.1 update.symantec.com
    127.0.0.1 updates.symantec.com
    127.0.0.1 us.mcafee.com
    127.0.0.1 liveupdate.symantec.com
    127.0.0.1 customer.symantec.com
    127.0.0.1 rads.mcafee.com
    127.0.0.1 trendmicro.com
    127.0.0.1 www.trendmicro.com
    127.0.0.1 www.grisoft.com



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: John Park

Discovered: April 16, 2005
Updated: February 13, 2007 12:37:13 PM
Also Known As: Win32.Glieder.{W, Y} [Computer Associates], Email-Worm.Win32.Bagle.{bj, bk} [Kaspersky Lab], W32/Bagle.dll.gen [McAfee], W32/Bagle.gen@MM [McAfee], W32/Bagle.bs.{dr, gen} [McAfee], Troj/BagDl-Gen [Sophos], Troj/BagleDl-N [Sophos], TROJ_BAGLE.BH [Trend Micro]
Type: Trojan Horse
Systems Affected: Windows


Removal using the W32.Beagle@mm Removal Tool
Symantec Security Response has developed a removal tool to clean the infections of Trojan.Tooso.H. Use this removal 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. Delete the value that was added to the registry and restart Windows.
  3. Remove the lines that were added to the Hosts file.
  4. Reinstall your Symantec antivirus program.
  5. Update the virus definitions.
  6. Run a full system scan and delete all the files detected as Trojan.Tooso.H.

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:
Note:
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 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.

  4. Navigate to the subkey:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run

  5. In the right pane, delete the value:

    "winshost.exe" = "%System%\winshost.exe"

  6. Exit the Registry Editor.

3. . To delete the lines that were added to the Windows Hosts file
Because this Trojan overwrites the Windows Hosts file, the contents of the file must be removed (except for one line) so that you can access many Web sites.

Note: If you are on a corporate network, you may have had a customized Hosts file. We suggest that you contact the network administrator before proceeding.

Follow the instructions for your operating system:
  • Windows 95/98/Me/NT/2000
    1. Click Start, point to Find or Search, and then click Files or Folders.
    2. Make sure that "Look in" is set to (C:) and that "Include subfolders" is checked.
    3. In the "Named" or "Search for..." box, type:

      hosts

    4. Click Find Now or Search Now.
    5. For each Hosts file that you find, right-click the file, and then click Open With.
    6. Deselect the "Always use this program to open this program" check box.
    7. Scroll through the list of programs and double-click Notepad.
    8. When the file opens, delete all the entries in the Hosts file, except for the following line:

      127.0.0.1     localhost
    9. Close Notepad and save your changes when prompted.

  • Windows XP
    1. Click Start > Search.
    2. Click All files and folders.
    3. In the "All or part of the file name" box, type:

      hosts

    4. Verify that "Look in" is set to "Local Hard Drives" or to (C:).
    5. Click More advanced options.
    6. Check Search system folders.
    7. Check Search subfolders.
    8. Click Search.
    9. Click Find Now or Search Now.
    10. For each Hosts file that you find, right-click the file, and then click Open With.
    11. Deselect the Always use this program to open this program check box.
    12. Scroll through the list of programs and double-click Notepad.
    13. When the file opens, delete all the entries in the Hosts file, except for the following line:

      127.0.0.1     localhost
    14. Close Notepad and save your changes when prompted.
4. To reinstall your Symantec antivirus program
As this virus attempts to remove the files and registry subkeys that your Symantec antivirus program uses, you may need to reinstall the program. If your Symantec antivirus program is not working properly, uninstall, and then reinstall it.

5. 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 document: 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 the document: 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.


6. 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 Trojan.Tooso.H, click Delete.

    Note:
    If your Symantec antivirus product reports that it cannot delete an infected file, Windows may be using the file. To fix 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.


Writeup By: John Park