W32.HLLW.Deborms.B

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Discovered: March 12, 2003
Updated: February 13, 2007 11:44:18 AM
Also Known As: Worm.Win32.Deborm.e[Kaspersky
Type: Worm
Systems Affected: Windows


W32.HLLW.Deborms.B is a worm that attempts to spread through a local network. The worm attempts to connect to port 139 (NetBIOS).

Antivirus Protection Dates

  • Initial Rapid Release version March 13, 2003
  • Latest Rapid Release version March 13, 2003
  • Initial Daily Certified version March 13, 2003
  • Latest Daily Certified version March 13, 2003
  • Initial Weekly Certified release date March 14, 2003

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

Writeup By: Robert X Wang

Discovered: March 12, 2003
Updated: February 13, 2007 11:44:18 AM
Also Known As: Worm.Win32.Deborm.e[Kaspersky
Type: Worm
Systems Affected: Windows


When W32.HLLW.Deborms.B runs, it does the following:

  1. Clears the security log on the infected computer.
  2. Creates 100 threads to infect all the computers in the local network. The worm attempts to log in to all the computers in the local network. If W32.HLLW.Deborms.B is successful, it copies itself to the following folders:
    • \Documents and Settings\All Users\Start Menu\Programs\Startup
    • \WINDOWS\Start Menu\Programs\Startup
    • \WINNT\Profiles\All Users\Start Menu\Programs\Startup
    • C:\Winnt\Profiles\All Users\Start Menu\Programs\Startup
    • C:\Windows\Start Menu\Programs\Startup
    • C:\Documents and Settings\All Users\Start Menu\Programs\Startup

  3. Adds a value:

    <random name>           <path to the worm>

    to the registry key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  4. If the infected computer is running Windows 95, 98, or Me, the worm adds the value:

    NetBIOS Worm            <path.to.the.worm>

    to the registry key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices

    NOTE: By default, the worm does not work on Windows 95, 98, or Me, because the worm imports API NetShareEnum from Netapi32.dll. Although API NetShareEnum is available in Windows 95, 98, and Me, the declaration it uses on these operating systems is different than the declaration used on NT-based systems.


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: Robert X Wang

Discovered: March 12, 2003
Updated: February 13, 2007 11:44:18 AM
Also Known As: Worm.Win32.Deborm.e[Kaspersky
Type: Worm
Systems Affected: Windows


The following instructions pertain to 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 record the names of any files detected as W32.HLLW.Deborms.B. Then, delete them if possible.
  3. Do one of the following:
    • Windows 95/98/Me: Restart the computer in Safe mode.
    • Windows NT/2000/XP: End the Trojan process.
  4. Run a full system scan and delete all the files detected as W32.HLLW.Deborms.B.
  5. Reverse the changes that the Trojan made to the registry.
For details on each of these steps, read the following instructions.

1. 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 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).
  • 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).

    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.

2. 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.HLLW.Deborms.B, first write down the filename, and then click Delete. (In many cases, you will not be able to delete the file, because Windows is using it.)
    • If you are able to delete all the detected files, skip to section 5.
    • If you are not able to delete all the detected files, go to section 3.

3. Restarting the computer in Safe mode or ending the worm process
    Windows 95/98/Me
    Restart the computer in Safe mode. All the Windows 32-bit operating systems, except for 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."

    Windows NT/2000/XP
    To end the worm process:
    1. Press Ctrl+Alt+Delete once.
    2. Click Task Manager.
    3. Click the Processes tab.
    4. Double-click the Image Name column header to alphabetically sort the processes.
    5. Scroll through the list and look for the process that has the same name as the file that was detected as infected with W32.HLLW.Deborms.B
    6. If the process is listed, click it, and then click End Process.
    7. Exit the Task Manager.
4. 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.HLLW.Deborms.B, click Delete.

5. Reversing the changes made to 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, and then click Run. (The Run dialog box appears.)
  2. Type regedit and then click OK. (The Registry Editor opens.)
  3. Navigate to the key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\Run
  4. In the right pane, find the value pointing to W32.HLLW.Deborms.B, and delete it.
  5. Navigate to the key:

    HKEY_LOCAL_MACHINE\Software\Microsoft\Windows\CurrentVersion\RunServices
  6. In the right pane, delete the following value, if it exists:

    NetBIOS Worm
  7. Exit the Registry Editor.


Writeup By: Robert X Wang