A threat is any circumstance or event with the potential to cause harm to a system in the form of destruction, disclosure, modification of data, and/or denial of service.
Information systems are subject to serious threats that can have adverse effects on organizational operations (including missions, functions, image, or reputation), organizational assets, individuals, other organizations, and the government by compromising the confidentiality, integrity, or availability of information being processed, stored, or transmitted by those systems.
Threats to information systems include environmental disruptions, human errors, and purposeful attacks. Attacks on information systems today are often well-organized, disciplined, aggressive, well-funded, and in a growing number of documented cases, extremely sophisticated. Successful attacks on public and private sector information systems can result in great harm to the national and economic security interests of a country.