|  |  | Viruses or Trojan Horses may cause anomalies on individual PCs and throughout the entire network. Viruses can delete files, format disks, and even delete the BIOS from a PC. A Trojan Horse may look like a gift or legitimate product (hence the name), but it hides in the background and picks up logins, passwords, system names, directories, etc. Trojans like Netbus or Back Orifice 2000 may give an attacker complete access to a host or network. ActiveX or JavaScript code from an attacker can cause damage to a host by rebooting the system, taking over the Web browser, or transferring money out of an online banking account.