Updated: February 13, 2007 11:50:01 AM
Type: Virus

Norton AntiVirus (NAV) has the ability to detect unknown viruses of various types using heuristic algorithms known as Bloodhound. This technology was developed by Symantec Security Response.

Addition information on Bloodhound.AOLPWS detections
When Norton AntiVirus detects a Bloodhound.AOLPWS Trojan horse program, it indicates the offending file by name. The file has different names depending on the version of the Trojan. Symantec Technical Support has encountered the following Trojan files to date:

Explore.exe (not Explorer.exe)
PKg5184.exe (This Trojan asks for credit card information.)
Setup.pkg (This file name is also used by some installation programs. Use caution in deleting it.)

Many of these files are named in such a way as to trick the unsuspecting user into thinking that they are Windows system files, and thus deter their removal. The Win.ini or System.ini files may also be marked read-only, making it difficult to remove the commands placed there by the Trojan.

To locate and remove Bloodhound.AOLPWS Trojans, follow these steps:

CAUTION: Because of the large number of these Trojans, these instructions are somewhat general, and by necessity, assume that you are familiar with the operating system and the use of Windows utilities such as the System Editor. If you are not, please contact a qualified computer consultant.

Locate the named Trojan program

  1. Click Start, point to Find, and click Files or Folder.
  2. Type the name of the file, and then press Enter.
  3. Right-click the file in the results pane, and click Delete.

Remove references to the Trojan from the Win.ini and System.ini files
  1. Click Start, and click Run.
  2. Type sysedit and then press Enter. The System Configuration Editor appears.
  3. Click the window titled C:\WINDOWS\WIN.INI.
  4. Beneath the [Windows] section, remove any references to the Trojan from the load= and run= lines.
  5. Click the window titled C:\WINDOWS\SYSTEM.INI.
  6. Beneath the [boot] section, the shell= line should read shell=explorer.exe

    NOTE: Some vendors, such as Compaq, may include a custom shell. In the case of a Compaq computer, this may read shell=cpqshell.exe. If in doubt, contact your vendor.
  7. Exit the System Configuration Editor, and click Yes when you are prompted to save changes.

    NOTE: If the read-only attribute is set for the Win.ini and System.ini files, then you will need to remove that attribute before you can save the files.

Remove references to the Trojan from the registry
These Trojans can load from the registry, and they need to be removed from the \Run key:

CAUTION : We strongly recommend that you back up the system registry before making any changes. Incorrect changes to the registry could result in permanent data loss or corrupted files. Please make sure you modify only the keys specified. Please see the document How to back up the Windows registry before proceeding.
  1. Click Start, and click Run. The Run dialog box appears.
  2. Type regedit and then click OK.
  3. Navigate to the following key:

  4. In the right pane, delete the value that refers to the Trojan.
  5. Close the Registry Editor. Any changes that you made are saved automatically.

Check the StartUp Folder
Some Trojans load from the Windows StartUp folder. Please follow these steps remove them:
  1. Click Start, point to Settings, and click Taskbar.
  2. Click the Start Menu Programs tab.
  3. Click Advanced, open the Programs folder, and then open the StartUp folder.
  4. In the right pane, locate the file that you want to remove (for example, System.exe), and select it. This may be the actual file, or a shortcut to it.
  5. Click the Edit menu, and click Cut.
  6. Open a folder of your choice into which you want to move the file or shortcut.
  7. Click the Edit menu, and click Paste.
  8. Close the window, click OK, and then restart the computer.

    NOTE: If you are sure that you do not need the file that is in the StartUp folder--by design, these should be shortcuts, rather than program files--you can delete them instead of moving them.

CAUTION: Because your password could have been compromised, we strongly recommend that you contact AOL customer service and change your password before you log back on.

Antivirus Protection Dates

  • Initial Rapid Release version December 19, 2000
  • Latest Rapid Release version February 17, 2018 revision 003
  • Initial Daily Certified version December 19, 2000
  • Latest Daily Certified version February 18, 2018 revision 001

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

Writeup By: Motoaki Yamamura

Updated: February 13, 2007 11:50:01 AM
Type: Virus

For more information about Bloodhound technology, please see the white paper Understanding Heuristics: Symantec's Bloodhound Technology .

When Bloodhound detects an unknown virus, Norton AntiVirus reports the virus name as one of the following:
Bloodhound.VBS.1 (probable IRC worm)
Bloodhound.VBS.2 (probable IRC worm)
Bloodhound.VBS.3 (probable Outlook worm)
Bloodhound.VBS.4 (probable VBS worm, created with worm generation tool)
Bloodhound.VBS.5 (probable VBS worm, created with worm generation tool)
Bloodhound.JS.1 (probable IRC worm)
Bloodhound.JS.2 (probable IRC worm)
Bloodhound.JS.3 (probable Outlook worm)


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: Motoaki Yamamura