VBS.Alcaul.Gen

SUMMARY

VBS.Alcaul.Gen is a worm that sends itself to all the contacts in the Microsoft Outlook Address Book. W32.Alcaul.Kit generates these VBS scripts.

Protection

• Virus Definitions (LiveUpdate™ Weekly) April 9, 2003
• Virus Definitions (Intelligent Updater) April 4, 2003

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: Low
• Large Scale E-mailing: Sends mail to contacts in the Microsoft Outlook Address Book.

Distribution

• Distribution Level: High
• Subject of Email: Variable
• Name of Attachment: Variable (typically with a .vbs file extension)
• Size of Attachment: Variable

TECHNICAL DETAILS

When VBS.Alcaul.Gen is executed it does the following:

1. Copies itself two to four times to various locations on the hard drive. Some of the filenames that it copies itself as are:
   • C:Worm.vbs
   • C:Vbsworm.vbs
   • C:Attachment1.vbs
   • C:Attachment2.vbs
   • C:Anytime.vbs
   • C:Xiandong.vbs
     
     
2. Sends itself to all the contacts in the Microsoft Outlook Address Book. The email format does not have a common structure; it attaches one or more of the VBS scripts it created in step 1.
   
3. May do any of the following:
   • Display messages.
   • Overwrite files with a certain extension. The default file extensions for this are .js and .html.
   • Create an mIRC script. The default location of the file is C:Program FilesMircScript.ini.
   • Download and run an updated version of the script as C:UIpdate.vbs.
   • Ping a certain URL 1,000 times.
   • Infect Microsoft Word documents with a macro virus.
   • Add the value:
     
     "*HLM"="<file name>"
     
     to the registry key:
     
     HKEY_LOCAL_MACHINESoftwareMicrosoftWindows
     CurrentVersionRun
     
     so that the worm runs when you start Windows.

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

These instructions pertain to all current and recent Symantec antivirus products, including the Symantec AntiVirus and Norton AntiVirus product lines.

1. Update the virus definitions.
2. Run a full system scan.
   • Delete any files detected as VBS.Alcaul.Gen.
   • Repair any files detected as Macro Component.
3. Reverse any changes made to the registry.

For specific details on each of these steps, read the following instructions.

1. 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 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 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).
  
  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.

2. 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.
   • 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 VBS.Alcaul.Gen, click Delete.
4. If any files are detected as infected with Macro Component, click Repair.

3. Reversing the changes made to 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 the specified keys only. Read the document, "How to make a backup of the Windows registry," for instructions.

1. Click Start, and then click Run. (The Run dialog box appears.)
2. Type regedit
   
   Then click OK. (The Registry Editor opens.)
   
3. Navigate to the key:
   
   HKEY_LOCAL_MACHINESoftwareMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the values:
   
   "*HLM"="<worm file name as detected by scan>"
   
5. Exit the Registry Editor.