W32.Kwbot.B.Worm

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Discovered: January 02, 2003
Updated: February 13, 2007 11:41:58 AM
Also Known As: W32/Rbit.worm [McAfee], Backdoor.Tankedoor.02 [KAV]
Type: Worm
Systems Affected: Windows


The W32.Kwbot.B.Worm attempts to spread itself through the KaZaA file-sharing network. It also has a Backdoor Trojan capability, allowing a hacker to gain control of the compromised computer. It is written in the Microsoft Visual C++ programming language and is compressed with UPX.

Note: The virus definitions released on October 8, 2003 contained an updated detection to account for the discovery of a minor variant of W32.Kwbot.B.Worm.

Antivirus Protection Dates

  • Initial Rapid Release version January 03, 2003
  • Latest Rapid Release version September 28, 2010 revision 054
  • Initial Daily Certified version January 03, 2003
  • Latest Daily Certified version September 28, 2010 revision 036
  • Initial Weekly Certified release date January 04, 2003

Click here for a more detailed description of Rapid Release and Daily Certified virus definitions.

Writeup By: Yana Liu

Discovered: January 02, 2003
Updated: February 13, 2007 11:41:58 AM
Also Known As: W32/Rbit.worm [McAfee], Backdoor.Tankedoor.02 [KAV]
Type: Worm
Systems Affected: Windows


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

  1. Copies itself as C:\%System%\MSInstall61.exe.

    NOTE: %System% is a variable. The worm locates the Windows System folder and copies itself to that particular location. By default, the location is C:\Windows\System (Windows 95/98/Me), C:\Windows\System32 (Windows XP), or C:\Winnt\System32 (Windows NT/2000).
  2. Adds the value

    Internet Loader1  C:\%SYSTEM%\MSInstall61.exe

    to the following registry keys:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
    CurrentVersion\RunServices
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\
    CurrentVersion\RunServices

    This causes the worm to run when you start Windows.
  3. Opens a randomly chosen TCP/UDP port to connect to the hacker.
  4. Copies itself to the default KaZaA shared folder using many different names randomly chosen from a list that the worm carries. Some examples are:
    • Howtouseashell.exe
    • Visio.exe
    • Worldbook.exe
    • HotGirls.exe
    • Linux.exe
    • Gta3.exe
    • Driver.exe
    • Hack_aim.exe
    • How_to_hack.exe
    • Divx_pro.exe
    • Pamela_anderson.scr
    • Wc3_keygen.exe
    • Hotmail_hack.exe

NOTE: The W32.Kwbot.B.Worm requires that the KaZaA software be installed on the computer for it to spread.

The W32.Kwbot.B.Worm contains its own Internet Relay Chat (IRC) client, allowing the worm to connect to an IRC channel, which was coded into the Trojan. Using the IRC channel, the Trojan listens for commands from the hacker. 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 defined by the hacker.
  • Completely uninstall itself by removing the relevant registry entries.


Recommendations

Symantec Security Response encourages all users and administrators to adhere to the following basic security "best practices":

  • Use a firewall to block all incoming connections from the Internet to services that should not be publicly available. By default, you should deny all incoming connections and only allow services you explicitly want to offer to the outside world.
  • 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.
  • Ensure that programs and users of the computer use the lowest level of privileges necessary to complete a task. When prompted for a root or UAC password, ensure that the program asking for administration-level access is a legitimate application.
  • Disable AutoPlay to prevent the automatic launching of executable files on network and removable drives, and disconnect the drives when not required. If write access is not required, enable read-only mode if the option is available.
  • Turn off file sharing if not needed. If file sharing is required, use ACLs and password protection to limit access. Disable anonymous access to shared folders. Grant access only to user accounts with strong passwords to folders that must be shared.
  • Turn off and remove unnecessary services. By default, many operating systems install auxiliary services that are not critical. These services are avenues of attack. If they are removed, threats have less avenues of attack.
  • If a 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.
  • Configure your email server to block or remove email that contains file attachments that are commonly used to spread threats, such as .vbs, .bat, .exe, .pif and .scr files.
  • Isolate compromised computers quickly to prevent threats from spreading further. 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.
  • If Bluetooth is not required for mobile devices, it should be turned off. If you require its use, ensure that the device's visibility is set to "Hidden" so that it cannot be scanned by other Bluetooth devices. If device pairing must be used, ensure that all devices are set to "Unauthorized", requiring authorization for each connection request. Do not accept applications that are unsigned or sent from unknown sources.
  • For further information on the terms used in this document, please refer to the Security Response glossary.

Writeup By: Yana Liu

Discovered: January 02, 2003
Updated: February 13, 2007 11:41:58 AM
Also Known As: W32/Rbit.worm [McAfee], Backdoor.Tankedoor.02 [KAV]
Type: Worm
Systems Affected: Windows


  1. Update the virus definitions.
  2. Restart in Safe mode.
  3. Run a full system scan and delete all the files detected as W32.Kwbot.B.Worm.
  4. Delete the value,

    Internet Loader1  C:\%SYSTEM%\MSInstall61.exe

    from the following registry keys:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
    CurrentVersion\RunServices
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\
    Windows\CurrentVersion\RunServices

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

Updating the virus definitions
Symantec Security Response fully tests all the virus definitions for quality assurance before they are posted to our servers. There are two ways to obtain the most recent virus definitions:
  • Running LiveUpdate, which is the easiest way to obtain the virus definitions. These virus definitions are posted to the LiveUpdate servers once each week (usually on Wednesdays), unless there is a major virus outbreak. To determine whether definitions for this threat are available by LiveUpdate, refer to the Virus Definitions (LiveUpdate), in the "Protection" section, at the top of this writeup.
  • Downloading the definitions using the Intelligent Updater. The Intelligent Updater virus definitions are posted on U.S. business days (Monday through Friday). You should download the definitions from the Symantec Security Response Web site and manually install them. To determine whether definitions for this threat are available by the Intelligent Updater, refer to the Virus Definitions (Intelligent Updater), in the "Protection" section, at the top of this writeup.

    The 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.


Restarting the computer in Safe mode
All Windows 32-bit operating systems, except Windows NT, can be restarted in Safe mode. For instructions on how to do this, read the document, "How to start the computer in Safe Mode ."

Scanning for and deleting the infected files
  1. Start your Symantec antivirus program and make sure that it is configured to scan all the files.
  2. Run a full system scan.
  3. If any files are detected as infected with W32.Kwbot.B.Worm, click Delete.

Editing 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 the specified keys only. Read the document, "How to make a backup of the Windows registry ," for instructions.
  1. Click Start, then click Run. (The Run dialog box appears.)
  2. Type regedit, then click OK. (The Registry Editor opens.)
  3. Navigate to each of these keys:

    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\
    CurrentVersion\RunServices
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Run
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\RunOnce
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\
    CurrentVersion\RunServices

    NOTE: All the keys will not be found on all the systems.
  4. For each one, look in the right pane and delete this value:

    Internet Loader1  C:\%SYSTEM%\MSInstall61.exe
  5. Click Registry, then click Exit.


Writeup By: Yana Liu