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Discovered: April 29, 2005
Updated: February 13, 2007 12:38:07 PM
Also Known As: Win32.Bropia.AK [Computer Asso, IM-Worm.Win32.Prex.d [Kaspersk, W32/Kelvir.worm.an [McAfee]
Type: Worm
Systems Affected: Windows

W32.Kelvir.AZ is a worm that sends a message to all MSN messenger contacts on the compromised computer.

Antivirus Protection Dates

  • Initial Rapid Release version April 30, 2005
  • Latest Rapid Release version April 30, 2005
  • Initial Daily Certified version April 30, 2005
  • Latest Daily Certified version April 30, 2005
  • Initial Weekly Certified release date May 04, 2005

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

Writeup By: Ka Chun Leung

Discovered: April 29, 2005
Updated: February 13, 2007 12:38:07 PM
Also Known As: Win32.Bropia.AK [Computer Asso, IM-Worm.Win32.Prex.d [Kaspersk, W32/Kelvir.worm.an [McAfee]
Type: Worm
Systems Affected: Windows

When W32.Kelvir.AZ is executed, it performs the following actions:

  1. Attempts to end any services and processes that contain the following strings:

    • Ahnlab Task Scheduler
    • altiris client service
    • ATRACK
    • avast! antivirus
    • avast! iavs4 control service
    • AVG6 Service
    • AVG7 Alert Manager Server
    • AVG7 Update Service
    • AVP control center service
    • AVP.EXE
    • AVP32
    • AVSync Manager
    • Background Intelligent Transfer Service
    • BlackICE
    • carbon copy access edition
    • CFINET
    • CFINET32
    • config loader
    • Detector de OfficeScanNT
    • directupdate engine
    • dllhost
    • dns
    • eTrust Antivirus Job Server
    • etrust antivirus job server
    • eTrust Antivirus Realtime Server
    • etrust antivirus realtime server
    • eTrust Antivirus RPC Server
    • etrust antivirus rpc server
    • Event Log
    • Eventask
    • FireBall
    • FireBaum
    • fix-it task manager
    • F-PROT95
    • F-STOPW
    • fxsvc
    • gear security
    • IAMAPP
    • ICMON
    • intel file transfer
    • intel pds
    • Internet Connection Firewall (ICF) / Internet Connection Sharing (ICS)
    • internet pr0tocol
    • InternetFirewallProc
    • IOMON98
    • IPSEC Policy Agent
    • iroff
    • Kaspersky
    • Kaspersky Antivirus
    • Kaspersky Anti-Virus
    • kaspersky auto protect service
    • Kaspersky Client
    • kav
    • KAV Moniter Service
    • kerio personal firewall
    • Kingsoft AntiVirus Service
    • LOCKDOWN2000
    • LUALL
    • MastDLL
    • MCAFEE
    • McAfee Agent
    • mcafee framework service
    • McAfee.com McShield
    • McAfee.com VirusScan Online Realtime Engine
    • McShield
    • mcshield
    • MonSvcNT
    • msclol2
    • msinit
    • MsInt
    • MsIntScan
    • NAV Alert
    • NAV Auto-Protect
    • NAVAPW32
    • NAVLU32
    • NAVW32
    • NAVWNT
    • NISUM
    • NMAIN
    • NORTON
    • Norton Antivirus Auto Protect Service
    • Norton AntiVirus Auto Protect Service
    • Norton AntiVirus Client
    • Norton AntiVirus Corporate Edition
    • Norton AntiVirus Server
    • Norton Internet Security Accounts Manager
    • Norton Internet Security Proxy Service
    • Norton Internet Security Proxy Srvice
    • Norton Internet Security Service
    • Norton Internet Security service
    • Norton Unerase Protection
    • nvscv
    • officescannt listener
    • OfficeScanNT Monitor
    • officescannt realtime scan
    • outpost firewall service
    • P2P Networking
    • Panda Antivirus
    • pcanywhere host service
    • PC-cillin Personal Firewall
    • PCCWIN98
    • POP3TRAP
    • psexesvc
    • PVIEW95
    • Quick Heal Online Protection
    • RemoteAgent
    • remotely possible/32
    • RESCUE32
    • rising process communication center
    • Rising Process Communication Center
    • rising realtime monitor service
    • Rising Realtime Monitor Service
    • rundll
    • savroam
    • sclol8
    • ScriptBlocking Service
    • scvhost
    • secur2
    • Security Center
    • services32 service: msinit
    • servu
    • Serv-U
    • serv-u-ftp
    • smss
    • snake sockproxy service
    • Sophos Anti-Virus
    • Sophos Anti-Virus Network
    • Sygate Personal Firewall
    • Sygate Personal Firewall Pro
    • SyGateService
    • symantec antivirus
    • Symantec AntiVirus Client
    • symantec central quarantine
    • Symantec Event Manager
    • Symantec Proxy Service
    • symantec quarantine agent
    • symantec quarantine scanner
    • syslock
    • System Event Notification
    • systemsecuritydll
    • task manager
    • Trend Micro Proxy Service
    • Trend NT Realtime Service
    • TrueVector Internet Monitor
    • V3MonNT
    • V3MonSvc
    • ViRobot Expert Monitoring
    • ViRobot Lite Monitoring
    • ViRobot Professional Monitoring
    • vnc server
    • VNC server
    • VSHWIN32
    • VSSTAT
    • win32sl
    • Windows Firewall
    • Windows Internet Connection Sharing(ICS)
    • WMDM PMSP Service
    • Zonealarm
    • ZoneAlarm

  2. Modifies the value:

    "Start" = "4"

    in the registry subkeys:

    HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\[service names]

    so that [service names] is set to Disabled.

    Note: [service names] is a variable for services listed under the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services subkey. The worm attempts to disable any services that contain the strings listed in step one.

  3. Sends the following message to all the MSN messenger contacts on the compromised computer:

    hey its you!
    [predetermined URL]=[email address]

    • [predetermined URL] is a variable for a URL on the pictures.templates.4friends.com domain.
    • [email address] is a variable for an email address specified by the worm.
    • The URL links to a copy of W32.Spybot.OFN.


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: Ka Chun Leung

Discovered: April 29, 2005
Updated: February 13, 2007 12:38:07 PM
Also Known As: Win32.Bropia.AK [Computer Asso, IM-Worm.Win32.Prex.d [Kaspersk, W32/Kelvir.worm.an [McAfee]
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. Restart the computer in Safe mode or end the malicious process
  4. Run a full system scan and delete all the files detected as W32.Kelvir.AZ.
  5. Reenable the services stopped by the threat.

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, 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 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 restart the computer in Safe mode or end the malicious process

Windows 95/98/Me
Shut down the computer and turn off the power. Wait for at least 30 seconds, and then restart the computer in Safe mode. For instructions, read the document: How to start the computer in Safe Mode .

Windows NT/2000/XP
To end the malicious process:
  1. Press Ctrl+Alt+Delete once.
  2. Click Task Manager.
  3. Click the Processes tab.
  4. Double-click the Image Name column header to alphabetically sort the processes.
  5. Scroll through the list and look for svc.exe.
  6. If you find the files, click them, and then click End Process.
  7. Exit the Task Manager.

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.Kelvir.AZ, 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.

    When all the infected files have been deleted, restart the computer in Normal mode.
5. To reenable the services
This threat disables a large number of services. In order to return all services to their original settings, you may need to consult the documentation of the programs associated with the services.
  1. Click Start > Run.
  2. Type services.msc, and then click OK.
  3. Locate and select any of the services stopped by the threat. (The strings listed above in step one of the Technical Description may help you determine which services have been stopped.)
  4. Click Action > Properties.
  5. Set the Startup Type to Automatic, Manual, or leave it set to Disabled, depending on the service's initial settings.
  6. Click OK to close the Services window.
  7. Restart the computer.

Writeup By: Ka Chun Leung