1. A method for determining a rating of a likelihood of a victim system receiving malicious traffic from an attacker system at a point in time, comprising: generating a first forecast from a time series model based on past history of attacks by the attacker system; generating a second forecast from a victim neighborhood model based on similarity between the victim system and peer victim systems; generating a third forecast from a joint attacker-victim neighborhood model based on correlation between a group of attacker systems including the attacker system and a group of victim systems including the victim system; and determining the rating of the likelihood of the victim system receiving malicious traffic from the attacker system at the point in time based on the first forecast, the second forecast, and the third forecast.