W32.Kwbot.Worm

SUMMARY

W32.Kwbot.Worm has backdoor Trojan capability, which allows a hacker to gain control of the compromised computer. The worm can update itself by checking for newer versions over the Internet. W32.Kwbot.Worm disguises itself as popular movie, game, or software files, and it attempts to spread across KaZaA file-sharing networks by tricking KaZaA users into downloading the program and opening it.

Behavior

Symptoms

Transmission

Protection

• Virus Definitions (LiveUpdate™ Weekly) June 19, 2002
• Virus Definitions (Intelligent Updater) June 19, 2002

Threat Assessment

Wild

• Wild Level: Medium
• Number of Infections: More than 1000
• Number of Sites: More than 10
• Geographical Distribution: High
• Threat Containment: Easy
• Removal: Moderate

Damage

• Damage Level: Low

Distribution

• Distribution Level: Low
• Ports: variable
• Shared Drives: KaZaA Shared folder

TECHNICAL DETAILS

When W32.Kwbot.Worm runs, it does the following:

It copies itself as C:\%System%Explorer32.exe.

NOTE: %System% is a variable. The worm locates the WindowsSystem folder (by default this is C:WindowsSystem or C:WinntSystem32) and copies itself to that location.

It adds the value

Windows Explorer Update Build 1142  C:\%SYSTEM%EXPLORER32.EXE

to the following registry keys:

HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRunServices

This causes the worm to run when you start Windows.

The worm opens a randomly chosen TCP port to connect to the hacker.

W32.Kwbot.Worm contains its own Internet Relay Chat (IRC) client. This allows the worm to connect to an IRC channel that was coded into the Trojan. Using the IRC channel, the Trojan listens for commands from the hacker. The hacker accesses the Trojan by using a password-protected authorization. The commands allow the hacker to perform any of the following actions:

• Manage the installation of the backdoor
• Control the IRC client on the compromised computer
• Dynamically update the installed Trojan
• Send the Trojan to other IRC channels to attempt to compromise more computers
• Download and execute files
• Deliver system and network information to the hacker
• Perform Denial of Service (DoS) attacks against a target that is defined by the hacker
• Uninstall itself completely by removing the relevant registry entries

How it spreads

NOTE: For W32.Kwbot.Worm to spread, it requires that the KaZaA software be installed on the computer.

The worm searches the Windows registry to locate the KaZaA shared folder. Other KaZaA users can download files from that location. The worm then copies itself into this folder using many different names that are chosen randomly from a list that the worm carries. Here are some examples:

• Sum of all Fears SVCD CD3.exe
• Star Wars Episode 2 - Attack of the Clones VCD CD2.exe
• Spiderman SVCD CD3.exe
• Grand Theft Auto 3 CD2 ISO.exe
• Playstation 2 PS2 Emulator.exe
• Windows XP Home to Professional Upgrade.exe
• Windows XP backdoor hack.exe
• Windows 2000 win2k password stealer.exe
• Microsoft Office XP Upgrade (from older versions).exe
• Macromedia Flash 5 Ultimate Study Guide.exe
• ZoneAlarm Firewall Pro.exe
• Norton Internet Security 2002.exe

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. Update the virus definitions, restart in Safe mode, and run a full system scan. Delete all files that Norton AntiVirus detects as W32.Kwbot.Worm.
2. Delete the value
   
   Windows Explorer Update Build 1142
   
   from the following registry keys:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRunServices

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

To scan with Norton AntiVirus and delete the infected files:

1. Obtain the most recent virus definitions. There are two ways to do this:
   • Run LiveUpdate, which is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers one time 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 have undergone full quality assurance testing by Symantec Security Response. They 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.
     
2. Start Norton AntiVirus (NAV), and make sure that NAV is configured to scan all files.
   • NAV Consumer products: Read the document How to configure Norton AntiVirus to scan all files.
   • NAV Enterprise products: Read the document How to verify a Symantec Corporate antivirus product is set to scan All Files.
3. Run a full system scan.
4. Delete all files that NAV detects as W32.Kwbot.Worm.

To remove the value from the registry:

CAUTION: Symantec strongly recommends that you back up the registry before you make any changes to it. Incorrect changes to the registry can result in permanent data loss or corrupted files. Modify only the keys that are specified. Read the document How to make a backup of the Windows registry for instructions.

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 each of these keys:
   
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRun
   HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindowsCurrentVersionRunServices
   
   For each one, look in the right pane, and delete this value:
   
   Windows Explorer Update Build 1142
   
4. Click Registry, and click Exit.