Discovered: January 07, 2003
Updated: February 13, 2007 11:42:07 AM
Also Known As: W32/Avril-A [Sophos], W32/Lirva.b@MM [McAfee], WORM_LIRVA.A [Trend], Win32.Lirva.A [CA], I-Worm.Avron.c [KAV], Lirva [F-Secure]
Type: Worm
Systems Affected: Windows
CVE References: CVE-2001-0154

NOTE: Due to a decreased rate of submissions, Symantec Security Response has downgraded this threat from a Category 3 to a Category 2 as of February 28, 2003.

W32.Lirva.A is a mass-mailing worm that also spreads by IRC, ICQ, KaZaA, and open network shares. This worm attempts to terminate antivirus and firewall products. It also emails the cached Windows 95/98/Me dial-up networking passwords to the virus writer.

When Microsoft Outlook receives the worm, the worm takes advantage of a vulnerability that allows the attachment to auto-execute when you read or preview the email. Information on this vulnerability and a patch can be found at .

If the day of the month is the 7th, 11th, or 24th, the worm will launch your Web browser to and display a graphic animation on the Windows desktop.

Antivirus Protection Dates

  • Initial Rapid Release version January 07, 2003
  • Latest Rapid Release version May 07, 2019 revision 006
  • Initial Daily Certified version January 07, 2003
  • Latest Daily Certified version May 07, 2019 revision 008
  • Initial Weekly Certified release date January 07, 2003

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

Technical Description

When W32.Lirva.A is executed, it does the following:

  1. Terminates all the processes with the following names:
    • _Avp32.exe
    • _avpcc.exe
    • _avpm.exe
    • Ackwin32.exe
    • Anti-trojan.exe
    • Apvxdwin.exe
    • Autodown.exe
    • Avconsol.exe
    • Ave32.exe
    • Avgctrl.exe
    • Avkserv.exe
    • Avp.exe
    • Avp32.exe
    • Avpcc.exe
    • Avpdos32.exe
    • Avpm.exe
    • Avpmon.exe
    • Avpnt.exe
    • Avptc32.exe
    • Avpupd.exe
    • Avsched32.exe
    • Avwin95.exe
    • Avwupd32.exe
    • Blackd.exe
    • Blackice.exe
    • Cfiadmin.exe
    • Cfiaudit.exe
    • Cfind.exe
    • Claw95.exe
    • Claw95ct.exe
    • Cleaner.exe
    • Cleaner3.exe
    • Dv95.exe
    • Dv95_o.exe
    • Dvp95.exe
    • Ecengine.exe
    • Efinet32.exe
    • Esafe.exe
    • Espwatch.exe
    • F-agnt95.exe
    • Findviru.exe
    • Fprot.exe
    • F-prot.exe
    • F-prot95.exe
    • Fp-win.exe
    • Frw.exe
    • F-stopw.exe
    • Iamapp.exe
    • Iamserv.exe
    • Ibmasn.exe
    • Ibmavsp.exe
    • Icload95.exe
    • Icloadnt.exe
    • Icmoon.exe
    • Icssuppnt.exe
    • Icsupp95.exe
    • Iface.exe
    • Iomon98.exe
    • Jed.exe
    • Kpf.exe
    • Kpfw32.exe
    • Lockdown2000.exe
    • Lookout.exe
    • Luall.exe
    • Moolive.exe
    • Mpftray.exe
    • N32scan.exe
    • Navapw32.exe
    • Navlu32.exe
    • Navnt.exe
    • Navsched.exe
    • Navw.exe
    • Navw32.exe
    • Navwnt.exe
    • Nisum.exe
    • Nmain.exe
    • Normist.exe
    • Nupgrade.exe
    • Nvc95.exe
    • Outpost.exe
    • Padmin.exe
    • Pavcl.exe
    • Pccwin98.exe
    • Pcfwallicon.exe
    • Persfw.exe
    • Rav7.exe
    • Rav7win.exe
    • Rescue.exe
    • Safeweb.exe
    • Scan32.exe
    • Scan95.exe
    • Scanpm.exe
    • Scrscan.exe
    • Serv95.exe
    • Smc.exe
    • Sphinx.exe
    • Sweep95.exe
    • Tbscan.exe
    • Tca.exe
    • Tds2-98.exe
    • Tds2-nt.exe
    • Vet95.exe
    • Vettray.exe
    • Vsecomr.exe
    • Vshwin32.exe
    • Vsscan40.exe
    • Vsstat.exe
    • Webscan.exe
    • Webscanx.exe
    • Wfindv32.exe
    • Zonealarm.exe
  2. Inventories all the windows and terminates any processes that have the following strings in the title bar of the window:
    • virus
    • anti
    • McAfee
    • Virus
    • Anti
    • AVP
    • Norton
  3. Copies itself as Hidden system files to:
    • %Temporary%\<random string>
    • %Temporary%\<random string>.tft
    • %System%\<random string>.exe
    • %All Drives%\Recycled\<random string>.exe
    • %Kazaa Downloads%\<random string>.exe
  4. Adds the value:

    Avril Lavigne - Muse

    to the registry key:


    so that it runs when you start Windows.

    If the operating system is Windows NT/2000/XP, the worm will register itself as a service.
  5. Creates the registry key:

    HKEY_LOCAL_MACHINE\Software\OvG\Avril Lavigne

    and various subkeys that the worm uses to keep track of its infection process.
  6. Creates a non-malicious text file %Temporary%\Avril-ii.inf and other temporary files in the Windows Temporary folder.
  7. Checks whether the computer is currently connected to a network. If it is not connected, the worm will attempt to dial out using the default dial-up connection profile.
  8. Searches the Windows Address Book and files with the extensions .dbx, .mbx, .wab, .html, .eml, .htm, .tbb, .shtml, .nch, and .idx for the email addresses. Then, the worm sends the email messages with the following characteristics:
    • Subject. The subject is one of the following:
      • Fw: Prohibited customers...
      • Re: Brigade Ocho Free membership
      • Re: According to Daos Summit
      • Fw: Avril Lavigne - the best
      • Re: Reply on account for IIS-Security
      • Re: ACTR/ACCELS Transcriptions
      • Re: The real estate plunger
      • Fwd: Re: Admission procedure
      • Re: Reply on account for IFRAME-Security breach
      • Fwd: Re: Reply on account for Incorrect MIME-header
    • Message. The message is one of the following:
      • Microsoft has identified a security vulnerability in Microsoft&reg; IIS 4.0 and 5.0 that is eliminated by a previously-released patch. Customers who have applied that patch are already protected against the vulnerability and do not need to take additional action. to apply the patch immediately. Microsoft strongly urges all customers using IIS 4.0 and 5.0 who have not already done so Patch is also provided to subscribed list of Microsoft Tech Support:
      • Restricted area response team (RART) Attachment you sent to %s is intended to overwrite start address at 0000:HH4F To prevent from the further buffer overflow attacks apply the MSO-patch
      • Avril fans subscription FanList admits you to take in Avril Lavigne 2003 Billboard awards ceremony Vote for I'm with you! Admission form attached below
    • Attachment. The attachment is one of the following:
      • Resume.exe
      • Download.exe
      • MSO-Patch-0071.exe
      • MSO-Patch-0035.exe
      • Two-Up-Secretly.exe
      • Transcripts.exe
      • Readme.exe
      • AvrilSmiles.exe
      • AvrilLavigne.exe
      • Complicated.exe
      • Singles.exe
      • Sophos.exe
      • Cogito_Ergo_Sum.exe
      • CERT-Vuln-Info.exe
      • Sk8erBoi.exe
      • IAmWiThYoU.exe
    • From. The worm uses the default SMTP server of the infected computer, and then adds either the address of the sender or a randomly selected email address to the "From:" line of the email.

      When Microsoft Outlook receives the worm, the worm takes advantage of a vulnerability that allows the attachment to auto-execute when you read or preview the email. Information on this vulnerability and a patch can be found at:
  9. As part of the email-sending routine, the worm creates the temporary file, %Temporary%\NewBoot.sys, which it (usually) deletes now.
  10. Searches for the file Icqmapi.dll, by determining the path of the ICQ program files. If the worm finds this file, the worm copies it to the \Windows\System folder and sends itself to all the contacts in the ICQ contact list.
  11. Creates a Script.ini file in the mIRC program files folder. This file will connect to the IRC channel #avrillavigne and send itself to others who join any channels that you join.
  12. Inventories all the network resources searching for open C shares. If the worm finds an open C share, it copies itself to \Recycled\<random string>.exe on the remote system and modifies the Autoexec.bat file of the remote system to load the worm on startup, by adding the following line:
    @win <random string>.exe
  13. Copies itself to \Recycled\<random string>.exe on each local hard drive and modifies the Autoexec.bat file (adding the aforementioned line), so that the worm runs when you start Windows (on Windows 95/98/Me computers only).
  14. Copies itself as a random file name to the KaZaA download folder.
  15. If the day of the month is the 7th, 11th, or 24th, the worm will launch your Web browser to and display a graphic animation on the Windows desktop.


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.


Removal tool
Symantec has provided a tool to remove infections of W32.Lirva.A@mm. Click here to obtain the tool. This is the easiest way to remove this threat and should be tried first.

Manual removal
These instructions are for all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

  1. Restart the computer in Safe mode.
  2. Remove the value that the worm added to the registry and restart in Normal mode.
  3. Update the virus definitions.
  4. Run a full system scan and delete all the files detected as W32.Lirva.A@mm.
For specific details on each of these procedures, read the following instructions.

1. Restarting in Safe mode
Restart the computer in Safe mode. All the Windows 32-bit operating systems, except Windows NT, can be restarted in Safe mode. For instructions, read the document, "How to start the computer in Safe Mode ."

2. Removing the value from the registry
Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify the specified keys only. For instructions, read the document, "How to make a backup of the Windows registry ."
  1. Click Start, and then click Run. (The Run dialog box appears.)
  2. Type regedit, and then click OK. (The Registry Editor opens.)
  3. Navigate to the key:

  4. In the right pane, delete the value:

    Avril Lavigne - Muse
  5. Exit the Registry Editor.
  6. Restart the computer and allow it to start in Normal mode.

3. Updating 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 the 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), in the "Protection" section, at the top of this writeup.
  • 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), in the "Protection" section, at the top of this writeup.

    The Intelligent Updater virus definitions are available here. For detailed instructions on how to download and install the Intelligent Updater virus definitions from the Symantec Security Response Web site, click here.

4. Scanning for and deleting 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.Lirva.A@mm, click Delete.

Writeup By: Atli Gudmundsson