Bugbear.B is dangerous worm that spreads via e-mail and across shared network drives.

It is very easy to become infected by this worm, as it is automatically activated when the message is viewed through Outlook's Preview Pane. It does this by exploiting a vulnerability in Internet Explorer (versions 5.01 and 5.5), which allows e-mail attachments to be automatically run. This vulnerability exploit is known as Exploit/iFrame. However, Bugbear.B does not always exploit this vulnerability in order to affect the computer.

Bugbear.B carries out the following actions in affected computers:

• It sends out a file containing a copy of the cached passwords of the dial-up connection to networks to a certain list of e-mail addresses. It does this if the default e-mail address of the victim computer, which it obtains from the Windows Registry, belongs to one of the domains in its list. This list mainly includes domains belonging to financial entities. The addresses it sends the cached passwords to are the following:
  ifrbr@canada.com, sdorad@juno.com, fbnfgh@email.ro, eruir@hotpop.com, ersdes@truthmail.com, eofb2@blazemail.com, ioter5@yook.de, iuery@myrealbox.com, jkfhw@wildemail.com and ds2iahf@kukamail.com.
• It infects a large number of files.
• It disables security programs.
• It opens port 1080, which allows hackers to gain remote access to the affected computer.
• It logs the keystrokes in a file. By doing this, hackers that accessed this file would be able to obtain confidential data such as passwords for accessing certain Internet services, bank accounts, etc. The logged information is sent when the data saved exceeds 25,000 bytes or every two hours.

Bugbear.B is a polymorphic worm, which makes it difficult for antivirus programs to detect.

Bugbear.B is difficult to recognize, as it does not display any warnings or messages that indicate that it has infected a computer.

When spreading across shared network drives, Bugbear.B does not check if the directories it is copying itself to are shared printers. Therefore, if it copies itself to one of these directories, the printer will start printing junk characters.