W32.Sinnaka.A@mm

SUMMARY

W32.Sinnaka.A@mm is a worm that uses its own SMTP engine to send itself as an email attachment.

Protection

• Virus Definitions (LiveUpdate™ Weekly) April 16, 2005
• Virus Definitions (Intelligent Updater) April 16, 2005

Threat Assessment

Wild

• Wild Level: Low
• Number of Infections: 0 - 49
• Number of Sites: 0 - 2
• Geographical Distribution: Low
• Threat Containment: Easy
• Removal: Easy

Damage

• Damage Level: Medium
• Large Scale E-mailing: Sends mails.
• Degrades Performance: Sending mails may degrade network performance.

Distribution

• Distribution Level: High
• Subject of Email: Varies
• Name of Attachment: Varies with a zip extension

TECHNICAL DETAILS

When W32.Sinnaka.A@mm is executed, it performs the following actions:

1. Copies itself as %System%lsess.exe.
   
   Note: %System% is a variable that refers to the System folder. By default this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).
   
   
2. Creates the following zip files, which are archive copies of the worm:
   
   
   • %System%lsess.zip
   • %System%credit card.zip
   • %System%edonkey 1.1.zip
   • %System%emoticons msn.zip
   • %System%hotmail passwords howto.me.zip
   • %System%lsess.zip
   • %System% orton antivirus.zip
   • %System%overnet full.zip
   • %System%windows commander.zip
   • %System%windows xp activate.zip
   • %System%winzip cracked.zip
     
     Note: %System% is a variable that refers to the System folder. By default this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).
     
     
3. Drops the following files:
   
   
   • %System%zlib.dll
   • %System$ansmtp.dll
     
     Note: %System% is a variable that refers to the System folder. By default this is C:WindowsSystem (Windows 95/98/Me), C:WinntSystem32 (Windows NT/2000), or C:WindowsSystem32 (Windows XP).
     
     
4. Adds the value:
   
   "lsess" = "%System%lsess.exe"
   
   to the registry subkeys:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   HKEY_CURRENT_USERSOFTWAREMicrosoftWindowsCurrentVersionRun
   HKEY_CURRENT_USERSOFTWAREMicrosoftWindowsCurrentVersionRunServicesOnce
   HKEY_CLASSES_ROOT xtfileshellopencommand
   
   so the the worm runs every time Windows starts.
   
   
5. Extracts email addresses from the files with one of the following extensions on the compromised computer:
   
   
   • .EML
   • .DOC
   • .DHTM
   • .DBX
   • .ADB
   • .ASP
   • .CFG
   • .CGI
   • .HTM
   • .JSP
   • .MBX
   • .MDX
   • .MHT
   • .MMF
   • .MSG
   • .NCH
   • .ODS
   • .OFT
   • .PHP
   • .PPT
   • .RTF
   • .SHT
   • .SHTM
   • .STM
   • .TBB
   • .TXT
   • .UIN
   • .VBS
   • .WAB
   • .WSH
   • .XLS
   • .XML
     
     
6. Avoids using addresses that contain the following strings:
   
   
   • @antivir
   • @avp
   • @fbi
   • @f-pro
   • @freeav
   • @f-secur
   • @kaspersky
   • @mcafee
   • @messagel
   • @microsof
   • @norman
   • @norton
   • @pandasof
   • @skynet
   • @sophos
   • @spam
   • @symatec
   • @viruslist
   • abuse@
   • noreply@
   • ntivir
   • reports@
   • spam@
     
     
7. Registers the SMTP engine by creating the following registry entries:
   
   HKEY_CLASSES_ROOTANSMTP.MassSender
   HKEY_CLASSES_ROOTANSMTP.MassSender.1
   HKEY_CLASSES_ROOTCLSID{253664FB-EDFC-4AC6-BD69-B322F466AEED}
   HKEY_CLASSES_ROOTCLSID{887A577B-406B-48FF-80CB-70752BFCD7B4}
   
   
8. Uses its own SMTP engine to send email messages to any addresses found. The email may have the following characteristics:
   
   Subject:
   One of the following:
   
   • Administration
   • Bad Request
   • Delivery Protection
   • Delivery Server
   • Encripted Mail
   • Error
   • Extended Mail
   • Extended Mail System
   • Failure
   • Mail Authentification
   • Mail Server
   • Notify
   • Protected Mail Delivery
   • Protected Mail Request
   • Protected Mail System
   • SMTP Server
   • Secure SMTP Message
   • Secure delivery
   • Status
   • Test
   • Thank you for delivery
   • Thanks!
   • approved
   • corrected
   • hello
   • here
   • hi
   • important
   • improved
   • patched
   • read it immediately
     
     Message:
     One of the following:
     
     
   • Bad Gateway: The message has been attached.
   • Delivered message is attached.
   • Encrypted message is available.
   • ESMTP [Secure Mail System #334]: Secure message is attached.
   • First part of the secure mail is available.
   • Follow the instructions t  read the message.
   • For further details see the attachment.
   • For more details see the attachment.
   • Forwarded message is available.
   • New message is available.
   • Now a new message is available.
   • Partial message is available. Waiting for a Response. Please read the attachment.
   • Please authenticate the secure message.
   • Please confirm my request.
   • Please read the attachment t  get the message.
   • Protected Mail System Test.
   • Protected message is attached.
   • Protected message is available.
   • Secure Mail System Beta Test.
   • SMTP: Please confirm the attached message.
   • Waiting for authentification.
   • You got a new message.
   • You have received an extended message. Please read the instructions.
   • Your requested mail has been attached.
     
     Followed by one of the following:
     
     
   • Authentication required.
   • I have attached your document.
   • Please see the attached file for details.
   • I have received your document. The corrected document is attached.
   • Please confirm the document.
   • Please read the attached file!
   • Please read the attached file!
   • Please read the document.
   • Please read the important document.
   • Requested file.
   • See the file.
   • Your details.
   • Your document is attached t  this mail.
   • Your document is attached.
   • Your document.
   • Your file is attached.
     
     Followed by:
     
     
   • +++ Attachment: No  Virus found
     
     Followed by one of the following:
     
     
   • +++ 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
     
     
     Attachment:
     One of the following:
     
     
   • data.zip
   • details.zip
   • document.zip
   • Message.zip
   • msg.zip
   • readme.zip
     
     Notes: The attachment is a zipped copy of the worm. It contains one of the following files:
     
     
   • Document.txt [many spaces].exe
   • Delails.doc [many spaces].exe
   • Data.txt [many spaces].exe
   • Readme.txt [many spaces].exe
     
     
9. Ends the following processes:
   
   
   • avpmon.exe
   • avp32.exe
   • VPC32
   • zonealarm.exe
   • vshwin32.exe
   • vet95.exe
   • tbscan.exe
   • serv95.exe
   • Nspclean.exe
   • clrav.com
   • scan32.exe
   • rav7.exe
   • navw.exe
   • outpost.exe
   • nmain.exe
   • navnt.exe
   • mpftray.exe
   • lockdown2000.exe
   • avpcc.exe
   • icssuppnt.exe
   • icload95.exe
   • iamapp.exe
   • findviru.exe
   • f-agnt95.exe
   • dv95.exe
   • dv95_o.exe
   • claw95ct.exe
   • cfiaudit.exe
   • avwupd32.exe
   • avptc32.exe
   • _avp32.exe
   • avgctrl.exe
   • apvxdwin.exe
   • _avpcc.exe
   • wfindv32.exe
   • vsecomr.exe
   • tds2-nt.exe
   • sweep95.exe
   • EFINET32.EXE
   • scrscan.exe
   • safeweb.exe
   • persfw.exe
   • navsched.exe
   • nvc95.exe
   • nisum.exe
   • navlu32.exe
   • ALOGSERV
   • AMON9X
   • AVGSERV9
   • AVGW
   • avkpop
   • avkservice
   • AvkServ
   • avkwctl9
   • AVXMONITOR9X
   • AVXMONITORNT
   • AVXQUAR
   • moolive.exe
   • jed.exe
   • icsupp95.exe
   • ibmavsp.exe
   • frw.exe
   • f-stopw.exe
   • espwatch.exe
   • procexp
   • filemon.exe
   • regmon.exe
   • dvp95.exe
   • cfiadmin.exe
   • avwin95.exe
   • avpm.exe
   • avp.exe
   • ave32.exe
   • anti-trojan.exe
   • webscan.exe
   • webscanx.exe
   • tds2-98.exe
   • SymProxySvc
   • SYMTRAY
   • TAUMON
   • TCM
   • TDS-3
   • TFAK
   • vbcmserv
   • VbCons
   • VSMAIN
   • vsmon
   • WIMMUN32
   • WGFE95
   • WEBTRAP
   • WATCHDOG
   • WrAdmin
   • sphinx.exe
   • scanpm.exe
   • taskmgr
   • rescue.exe
   • pcfwallicon.exe
   • pavcl.exe
   • nupgrade.exe
   • navwnt.exe
   • navapw32.exe
   • luall.exe
   • iomon98.exe
   • icmoon.exe
   • fprot.exe
   • f-prot95.exe
   • esafe.exe
   • cleaner3.exe
   • IBMASN.EXE
   • AVXW
   • cfgWiz
   • CMGRDIAN
   • CONNECTIONMONITOR
   • CPDClnt
   • DEFWATCH
   • CTRL
   • defalert
   • defscangui
   • DOORS
   • EFPEADM
   • ETRUSTCIPE
   • EVPN
   • EXPERT
   • fameh32
   • fch32
   • fih32
   • blackice.exe
   • avsched32.exe
   • avpdos32.exe
   • avpnt.exe
   • avconsol.exe
   • ackwin32.exe
   • NWTOOL16
   • pccwin97
   • PROGRAMAUDITOR
   • POP3TRAP
   • PROCESSMONITOR
   • PORTMONITOR
   • POPROXY
   • pcscan
   • pcntmon
   • pavproxy
   • PADMIN
   • pview95
   • rapapp.exe
   • REALMON
   • RTVSCN95
   • vsstat.exe
   • vettray.exe
   • tca.exe
   • smc.exe
   • scan95.exe
   • rav7win.exe
   • gbmenu
   • pccwin98.exe
   • KPFW32.EXE
   • ADVXDWIN
   • padmin.exe
   • normist.exe
   • navw32.exe
   • n32scan.exe
   • lookout.exe
   • iface.exe
   • icloadnt.exe
   • SPYXX
   • SS3EDIT
   • SweepNet
   • iamserv.exe
   • fp-win.exe
   • f-prot.exe
   • fsmb32
   • ecengine.exe
   • cleaner.exe
   • cfind.exe
   • blackd.exe
   • RULAUNCH
   • sbserv
   • SWNETSUP
   • WrCtrl
   • avpupd.exe
   • avkserv.exe
   • autodown.exe
   • _avpm.exe
   • regedit.exe
   • msconfig.exe
   • FPROT95.EXE
   • sfc.exe
   • fsma32
   • regedt32.exe
   • offguard.exe
   • pav.exe
   • pavmail.exe
   • per.exe
   • perd.exe
   • pertsk.exe
   • perupd.exe
   • pervac.exe
   • pervacd.exe
   • th.exe
   • th32.exe
   • th32upd.exe
   • thav.exe
   • thd.exe
   • thd32.exe
   • thmail.exe
   • alertsvc.exe
   • amon.exe
   • kpf.exe
   • antivir
   • avsynmgr.exe
   • cfinet.exe
   • cfinet32.exe
   • icmon.exe
   • lockdownadvanced.exe
   • lucomserver.exe
   • mcafee
   • navapsvc.exe
   • navrunr.exe
   • nisserv.exe
   • nsched32.exe
   • pcciomon.exe
   • pccmain.exe
   • pview95.exe
   • Avnt.exe
   • Claw95cf.exe
   • Dvp95_0.exe
   • Vscan40.exe
   • Icsuppnt.exe
   • Jedi.exe
   • N32scanw.exe
   • Pavsched.exe
   • Pavw.exe
   • Avrep32.exe
   • Monitor.exe
   • fsgk32
   • fsm32
   • GBPOLL
   • GENERICS
   • GUARD
   • IAMSTATS
   • ISRV95
   • LDPROMENU
   • LDSCAN
   • LUSPT
   • MCMNHDLR
   • MCTOOL
   • MCUPDATE
   • MCVSRTE
   • MGHTML
   • MINILOG
   • MCVSSHLD
   • MCAGENT
   • MPFSERVICE
   • MWATCH
   • NeoWatchLog
   • NVSVC32
   • NWService
   • NTXconfig
   • NTVDM
   • ntrtscan
   • npssvc
   • npscheck
   • netutils
   • ndd32
   • NAVENGNAVEX15
   • notstart.exe
   • zapro.exe
   • pqremove.com
   • BullGuard
   • CCAPP.EXE
   • vet98.exe
   • VET32.EXE
   • VCONTROL.EXE
   • claw95.exe
   • ANTS
   • ATCON
   • ATUPDATER
   • ATWATCH
   • AutoTrace
   • AVGCC32
   • AvgServ
   • AVWINNT
   • fnrb32
   • fsaa
   • fsav32
   • ZAP.EXE
   • ZAPD.EXE
   • ZAPPRG.EXE
   • ZAPS.EXE
   • ZCAP.EXE
   • VPTRAY

Recommendations

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

• Turn off and remove unneeded services. By default, many operating systems install auxiliary services that are not critical, such as an FTP server, telnet, and a Web server. These services are avenues of attack. If they are removed, blended threats have less avenues of attack and you have fewer services to maintain through patch updates.
• If a blended 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 (for example, all Windows-based computers should have the current Service Pack installed.). Additionally, please apply any security updates that are mentioned in this writeup, in trusted Security Bulletins, or on vendor Web sites.
• 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.
• Configure your email server to block or remove email that contains file attachments that are commonly used to spread viruses, such as .vbs, .bat, .exe, .pif and .scr files.
• Isolate infected computers quickly to prevent further compromising your organization. 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.

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. Run a full system scan and delete all the files detected as W32.Sinnaka.A@mm.
4. Delete the value that was 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:

• "How to disable or enable Windows Me System Restore"
• "How to turn off or turn on Windows XP System Restore"

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 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 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 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.
   • For Norton AntiVirus consumer products: Read the document, "How to configure Norton AntiVirus to scan all files."
   • For Symantec AntiVirus Enterprise products: Read the document, "How to verify that a Symantec Corporate antivirus product is set to scan all files."
2. Run a full system scan.
3. If any files are detected as infected with W32.Sinnaka.A@mm, 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.
   
   (After the files are deleted, you can leave the computer in Safe mode and proceed with section 4. When that is done, restart the computer in Normal mode.)
   

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 keys only. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Click Start > Run.
2. Type regedit
   
   Then click OK.
   
   
3. Navigate to the keys:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   HKEY_CURRENT_USERSOFTWAREMicrosoftWindowsCurrentVersionRun
   HKEY_CURRENT_USERSOFTWAREMicrosoftWindowsCurrentVersionRunServicesOnce
   HKEY_CLASSES_ROOT xtfileshellopencommand
   
   
4. In the right pane, delete the value:
   
   "lsess" = "%System%lsess.exe"
   
   
5. Navigate to and delete the following registry keys:
   
   HKEY_CLASSES_ROOTANSMTP.OBJ.1
   HKEY_CLASSES_ROOTANSMTP.OBJ
   HKEY_CLASSES_ROOTANSMTP.MassSender.1
   HKEY_CLASSES_ROOTANSMTP.MassSender
   HKEY_CLASSES_ROOTCLSID{253664FB-EDFC-4AC6-BD69-B322F466AEED}
   HKEY_CLASSES_ROOTCLSID{887A577B-406B-48FF-80CB-70752BFCD7B4}
   HKEY_CLASSES_ROOTTypelib{DE6317F7-6EF0-45C2-88D1-8E09415817F1}
   HKEY_CLASSES_ROOTInterface{68B8DCDB-EFA4-420A-BB8A-71B9892A2063}
   HKEY_CLASSES_ROOTInterface{1E98666F-6260-42C9-B846-32B20fDEFE7B}
   HKEY_CLASSES_ROOTInterface{A5F6C90C-ABE4-4C57-A421-8C5A202AA9F8}
   HKEY_CLASSES_ROOTInterface{B13281CF-8778-4C98-AE23-ABBA4637A33D}
   
6. Exit the Registry Editor.