VBS.Jer(htm)

SUMMARY

This worm appears as the attachment Jer.htm. Opening the attachment in your Internet browser displays a page that contains "The 40 Ways Women Fail in Bed". This is meant to serve as a distraction while the worm does its work in the background. There is a script embedded within the .htm file that allows the worm to spread itself via MS Outlook and mIRC.

Protection

• Virus Definitions (Intelligent Updater) July 6, 2000

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 Trigger: Opening the jer.htm file in a web browser that supports scripts.
• Large Scale E-mailing: Sends to all addresses in the Outlook Address book. Also spreads when connecting through mIRC.
• Modifies Files: System registry, Script.ini
• Causes System Instability: Could overload mail servers

Distribution

• Distribution Level: Low
• Subject of Email: Jer Resume
• Name of Attachment: Jer.htm
• Size of Attachment: 16,451 bytes

TECHNICAL DETAILS

The VBS.Jer(htm) script-worm is based on VBS.LoveLetter. This worm is embedded within a .htm file. It propagates by mass-mailing through MS Outlook and through a file transfer in mIRC. This worm modifies the registry key

HKLMSoftwareMicrosoftWindowsCurrentVersionRun

by adding the value "GinSenG" and setting it equal to the location of the Jer.htm file. This file gets created in your Windows system directory. Modifying the aforementioned registry key allows the worm to enable itself when the computer restarts.

The worm also modifies the following registry keys to disable certain functions of the OS:

HKLMSoftwareMicrosoftWindowsCurrentVersionPoliciesExplorerNoFind is set to "1".
HKLMSoftwareMicrosoftWindowsCurrentVersionPoliciesExplorerNoDesktop is set to "1".
HKLMSoftwareMicrosoftWindowsCurrentVersionPoliciesExplorerNoClose is set to "1".
HKLMSoftwareMicrosoftWindowsCurrentVersionVersion is set to "VBS.GinSenG".
HKLMSoftwareMicrosoftWindowsCurrentVersionRegisteredOwner is set to "I Love You, Min".
HKLMSoftwareMicrosoftWindowsCurrentVersionRegisteredOrganization is set to "GinsengBoy 2000".
HKLMSoftwareMicrosoftWindowsCurrentVersionPoliciesNetworkNoNetSetup is set to "1".

This corresponds to the following effects:

• The Find function is not accessible.
• All icons are disabled and no longer appear on the desktop.
• The user is prevented from shutting down the computer through the Start menu. The computer must be powered off, reset, or shut down by pressing Ctrl+Alt+Del and then selecting shut down.
• The Version and RegisteredOwner/Organization keys do not have an adverse affect on the system. These keys modify the data that can be seen when the System Properties are displayed.
• Access to Network Properties is disabled on Windows98 computers.

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.