VBS.Vbswg2.gen

SUMMARY

SARC has become aware of a new worm script generation kit. VBS.Vbswg2.gen is a generic detection for worms created using the worm generator Vbswg 2 (VBS Worm Generator 2). As of this time, SARC has not received any samples of worms generated by this kit.

The retail version of Norton AntiVirus 2001 running on a Windows 9X system will already catch worms generated by this program through a feature called script blocking. In order to activate this feature, users running retail NAV 2001 must manually run LiveUpdate to download the latest definitions. This is done by opening up the NAV console and clicking on LiveUpdate.

NOTE: Some of the generated worms will be detected as Bloodhound.VBS.worm

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (Intelligent Updater) March 14, 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

Distribution

• Distribution Level: Low

TECHNICAL DETAILS

Vbswg2 is a VBS worm generator written by an Argentinian virus writer. There are currently at least ten different known versions of this generator. Many of the versions have bugs in them that causes generated worms to not spread as intended. This mainly applies to the older versions of the generator. Norton AntiVirus will detect any worm that utilizes Microsoft Outlook to propagate that is created with any of these generators.

The generators have many options in them. In the later versions there is an option to encrypt the generated worm. This is done to avoid detection by antivirus programs. Norton Antivirus will detect any worm that has been generated or encrypted with any version of the generator.

When generating a worm, the author can choose how it should spread, what damage it should cause to the system, if it should have a payload or not. Once the desired malicious options have been chosen, a VBS worm can be generated.

The Argentinian virus writer that created the worm generators also created a malicious program to encrypt existing VBS Worms. Again, this was done in an attempt to hide from antivirus product. Norton Antivirus will detect worms encrypted with this malicious program as VBS.Vbswg2.gen.

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

1. Run LiveUpdate to make sure that you have the most recent virus definitions.
2. Start Norton AntiVirus (NAV), and then run a full system scan, making sure that NAV is set to scan all files.
3. Delete any files detected as VBS.Vbswg2.gen