VBS.Erul.A@mm

SUMMARY

VBS.Erul.A@mm is a simple Visual Basic Script (VBS) worm that sends email to all contacts that are in the Microsoft Outlook address book. It searches for all files that have the extension .vbs and overwrites them with itself. It also creates a copy of itself in the C:Windows folder as Failure.dll.vbs.

Protection

• Virus Definitions (Intelligent Updater) September 21, 2001

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
• Payload: Atttempts to overwrite all .vbs files
• Large Scale E-mailing: Yes
• Modifies Files: Yes

Distribution

• Distribution Level: High
• Subject of Email: Alarm!! Virus Alert
• Name of Attachment: Failure.dll.vbs
• Size of Attachment: 1781 bytes

TECHNICAL DETAILS

When executed, this worm copies itself as C:WindowsFailure.dll.vbs.

Next, it creates the value

Failure.dll  wscript.exe c:windowsFailure.dll.vbs %
in the registry key

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun

which causes the worm to run when you start Windows.

If it has not already mailed itself, it has a 50-percent chance of displaying a message with the title "VBS.Failure.A" and the text

Hello!!!

It then mails itself to all contacts that are in the Microsoft Outlook address book. This worm adds itself as an attachment to every email message that it mails out.
The message has the following characteristics:

Subject: Alarm!! Virus Alert
Message: Virus Alert!!
Attachment: Failure.dll.vbs.

Next, the worm attempts to overwrite all .vbs files on all mapped and local drives with itself.

Finally, after the email routine is finished, the worm creates the registry key

HKEY_CURRENT_USERSoftwareFailuremailed

with the value 1.

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

To remove this worm, delete files detected as VBS.Erul.A@mm and remove the value that the worm added to the registry /Run key.

To delete VBS.Erul.A@mm:

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 VBS.Erul.A@mm. Deleted files will have to be replaced from a clean backup.

To edit the registry:

CAUTION: We strongly recommend that you back up the system registry before you make any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure that you modify only the keys that are specified. Please see the document How to back up the Windows registry before you proceed.

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_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   
4. In the right pane, delete the following value:
   
   Failure.dll  wscript.exe c:windowsFailure.dll.vbs %
   
5. Click Registry, and then click Exit.

NOTE: It is not necessary to remove the key HKEY_CURRENT_USERSoftwareFailuremailed because it is harmless and will prevent future mailings if the computer were to be reinfected by this worm.