W32.LastScene@mm

SUMMARY

W32.LastScene@mm is a Trojan horse that drops a Visual Basic Script (VBS) file that emails Backdoor Trojan component to all recipients in the Microsoft Outlook address book.

Virus definitions dated prior to January 11, 2002 will detect this as Backdoor.Trojan or Virus.Dropper.

Protection

• Virus Definitions (Intelligent Updater) January 11, 2002

Threat Assessment

Wild

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

Damage

• Damage Level: Low
• Large Scale E-mailing: Mails itself to all users in the Microsoft Outlook address book
• Releases Confidential Info: Allows Unauthorized access,

Distribution

• Distribution Level: High
• Subject of Email: Scene From Last Weekend
• Name of Attachment: scenes.zip

TECHNICAL DETAILS

W32.LastScene@mm is received as the file Scenes.zip. Within this .zip file is the file Scenes.wri. The Scenes.wri file contains two files:

• The Backdoor Trojan installer and mailer file
• An uninfected .jpg file

If it is run, the installer drops a .vbs file into the Windows temporary folder. The .vbs file mails the original .zip file to all contacts in your Microsoft Outlook address book. This email has the following characteristics:

Subject: Scene from last weekend.
Message: Please do not forward!!!
Attachment: Scenes.zip

The installer also drops an uninfected .jpg file into the temporary folder, and opens it in the program that you have set as the default to display .jpg files.

The last file that the installer drops is the Backdoor Trojan. This Backdoor Trojan is installed to:

C:WindowsOlefilesRealuptd.exe

It then adds the value:

Common Startup     C:WINDOWSOleFiles

to the registry key:

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerShell Folders

so that the Trojan runs when Windows starts.

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

Delete all files that are detected as W32.LastScene@mm, and remove the registry value that the Trojan added.

To remove the Trojan:

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files. For instructions on how to do this, read the document How to configure Norton AntiVirus to scan all files.
3. Run a full system scan.
4. Delete all files that are detected as W32.LastScene@mm or Backdoor.Trojan or Virus.Dropper.

To edit the registry:

CAUTION: We strongly recommend 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 back up 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_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionExplorerShell Folders
   
4. In the right pane, delete the following value:
   
   Common Startup     C:WINDOWSOleFiles
   
5. Click Registry, and then click Exit.