Backdoor.Vmz

SUMMARY

Backdoor.Vmz is a Trojan that installs an IRC client on the computer; this allows a hacker to control the computer through IRC. The client allows the uploading and downloading of pirated movies.

Protection

• Virus Definitions (LiveUpdate™ Weekly) December 18, 2002
• Virus Definitions (Intelligent Updater) December 18, 2002

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

When the Trojan runs, it installs the following files to %system32%MicrosoftCrypto:

NOTE: %system32% is a variable. The Trojan locates the System32 folder and copies itself to the Microsoft folder in that location.

• Cygregex.dll: This file is not viral.
• Cygwin1.dll: This file is not viral.
• Firedaemon.exe: This file is not viral; it is a commercial program that registers a service.
• First.exe: This is an IRC bot.
• Ir.dll: This is a plain-text configuration file.
• Regex.dll: This file is not viral.
• Scv.bat: This is a batch file that is used to launch the other files.
• Scvhost.exe: This is an IRC file server.
• Wait.com: This file is not viral. It is a program that is used to create a time delay.

Only First.exe, Scv.bat, and the original installer are detected by Symantec antivirus products. The other files do not contain malicious code.

Scv.bat registers the IRC file server as a service and executes the IRC bot, allowing a hacker to control the system and begin using the system for the uploading and downloading of pirated movies using IRC.

In addition, these programs may create several plain-text log files.

This program has been discovered on systems that have not been patched against the Web Server Folder Traversal vulnerability in Microsoft Internet Information Server (IIS). A patch for this vulnerability can be found at http://www.microsoft.com/windows2000/downloads/critical/q269862/default.asp.

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

NOTE: These instructions are for 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, and delete all files that are detected as Backdoor.Vmz.

For details on how to do this, read the following instructions.

To update the virus definitions:
All virus definitions receive full quality assurance testing by Symantec Security Response before being posted to our servers. There are two ways to obtain the most recent virus definitions:

• Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually Wednesdays) unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, look at the Virus Definitions (LiveUpdate) line at the top of this write-up.
• Download the definitions using the Intelligent Updater. Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response Web site and installed manually. To determine whether definitions for this threat are available by the Intelligent Updater, look at the Virus Definitions (Intelligent Updater) line at the top of this write-up.
  
  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.

To scan for and delete the infected files:

1. Start your Symantec antivirus program, and make sure that it is configured to scan all files.
   • Norton AntiVirus consumer products: Read the document How to configure Norton AntiVirus to scan all files.
   • Symantec enterprise antivirus products: Read the document How to verify 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 Backdoor.Vmz, click Delete.