W32.Liac.A@mm is a mass-mailing worm that is written in Visual Basic. When the worm is executed, it attempts to use Microsoft
Outlook to send email to all contacts in the Windows Address Book (.wab). The worm has been packed using a known
executable file packer.The size of the worm is about 12 KB packed and about 40 KB unpacked.

Wild:

• Number of infections: 50 - 999
• Number of sites: 0 - 2
• Geographical distribution: Low
• Threat containment: Low
• Removal: Low

Distribution:

• Subject of email: FW:FW: LILAC project video attach
  Name of attachment: LILAC_WHAT_A_WONDERFULNAME.avi.exe
  Size of attachment: 12,208 bytes

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

It displays this message:

Title bar: Windows
Message: Error54: Media Player not installed correctly

Next, it attempts to copy itself to the Windows temporary folder. It does this by trying these hardcoded folder names:

• C:\Win98\Temp
• C:\Win95\Temp
• C:\Winnt\Temp
• C:\Winme\Temp
• C:\Winxp\Temp
• C:\Windows\Temp

Recommendations

Symantec Security Response offers these suggestions on how to configure Symantec products in order to minimize your exposure to this threat.

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.
• 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

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

1. Update the virus definitions, run a full system scan, and delete all files that delete all files that are detected as W32.Liac.A@mm
2. Delete the value

Lilac

from the registry key

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

Update the virus definitions, run a full system scan, and delete all files that that are detected as W32.Liac.A@mm. For details on how to do this, read the following instructions.

To scan for and delete the infected files:

1. Obtain the most recent virus definitions. There are two ways to do this:
• Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
• Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions have undergone full quality assurance testing by Symantec Security Response. They are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.
  
  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.
  
2. Start your Symantec antivirus software and make sure that it is configured to scan all files.
• Norton AntiVirus Consumer products: Read the document How to configure Norton AntiVirus to scan all files.
• Symantec Enterprise antivirus products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
3. Run a full system scan.
4. If any files are detected as infected by W32.Liac.A@mm click Delete.

To remove the value from the registry:

CAUTION: 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 only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.

1. Click Start, and click Run. The Run dialog box appears.
2. Type regedit and then click OK. The Registry Editor opens.
3. Navigate to the following key:

HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run

4. In the right pane, delete the following value:

Lilac

5. Click Registry, and click Exit.