1. A method of determining a likelihood of an attack on a first computer system of a first business, the method comprising the steps of: a computer determining characteristics of the first business, the characteristics including an industry, a size, and a geographical location of the first business, a type of sensitive data managed by the first computer system, a security vulnerability in the first computer system, and an address of a source or a destination of data traffic through a security device in the first computer system; the computer determining characteristics of a second business which has a second computer system currently or recently under attack, the characteristics of the second business including an industry, a size, and a geographical location of the second business, a type of sensitive data managed by the second computer system, a security vulnerability in the second computer system, and an address of an entity responsible for the current or recent attack on the second computer system; the computer determining a similarity between the characteristics of the first and second businesses; and based on the similarity, the computer determining a likelihood that the entity responsible for the current or recent attack on the second computer system will attack the first computer system of the first business.