A Threat is a possible security violation that might exploit the vulnerability of a system or asset. The origin of threat may be accidental, environmental (natural disaster), human negligence or human failure. There are three main types of threats:
Natural threats, such as floods, hurricanes, or tornadoes
Intentional threats, such as spyware, malware, adware companies, or the actions of a disgruntled employee.
An Attack is an deliberate unauthorized action on a system or asset. An Attack can be classified as active and passive attack. An attack will have a motive and will follow a method when opportunity arise.