VBS.Vierika@mm

SUMMARY

VBS.Vierika@mm is a worm that emails itself to all addresses in the Outlook address book with the following email attributes:

Subject: Vierika is here
Body text: Vierika.jpg
Attachment: Vierika.JPG.vbs

Protection

• Virus Definitions (Intelligent Updater) March 5, 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
• Compromises Security Settings: Internet Explorer security settings are lowered to allow the HTML part to be run

Distribution

• Distribution Level: High
• Subject of Email: Vierika is here
• Name of Attachment: Vierika.JPG.vbs
• Size of Attachment: 344 bytes
• Target of Infection: All email addresses in the Outlook address book

TECHNICAL DETAILS

VBS.Vierika@mm consists of 2 components (files). A VBS file and a HTML file.

The VBS file changes the Internet Explorer security settings so that it can freely execute the HTML component after it is loaded from a remote site. The VBS file also changes the Start Page of Internet Explorer to set it to an Italian URL. This URL contains the second component, the HTML file that contains the actual worm code.

When the HTML file is run, it first sets the Internet Explorer Start Page to the Italian URL so that it gets run again the next time Internet Explorer is started.
Second, the HTML file inserts a contaminated VBS file at C:Vierika.JPG.vbs.
Finally, the HTML file emails itself to all address entries in all the address lists of the Outlook address book with the following email details:

• Subject:
  Vierika is here
• Body text:
  Vierika.jpg
• Attachment:
  Vierika.JPG.vbs

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 any files detected as VBS.Vierika@mm and restore the proper security settings on Internet Explorer.