In infosec jargon, the Red Team is the team playing the role of the attacker. This might be trying to crack a database, phishing passwords from employees, or physically breaking into a building. This is done so that an organization can spot weaknesses and correct them. While the red team is the attacking team, it does not refer to actual criminal activity.
The defending team may not exist as a team of people, simply being the security systems currently in place. Regardless, these current systems and people that the Red Team is working against are referred to as the Blue Team.