A group that performs the role of a threat actor in order to provide security feedback.
What is a Red Team?
A red team is made up of professionals who are asked to act as an adversarial group in order to identify vulnerabilities and security gaps in a system, product, or organization's security infrastructures.
What is a Typical Red Team Process/Methodology?
A basic red team exercise involves having one team member pretend to be another person while the rest of the team plays as defenders of a security program. This approach allows for the testing of defensive measures and response capabilities against attacks from different angles. (Note, the attacker must have access to all information available to the defender. If the attacker does not know anything about the tested defenses, the results will likely be inconclusive.) In this scenario, it would not matter if the defender was aware of the attack, because they could still defend themselves effectively. However, if the defender were unaware of the attack, there might be some confusion over who attacked whom.
There is no set number of participants required for a successful red team. It depends entirely upon the size of your environment and the type of tests you want to perform. For example, if you're trying to find ways to break through firewalls, you'll need more than two people. On the other hand, if you're looking at social engineering techniques, you only really need three people: the attacker, the defender, and the observer.
Red teams are used to identify potential threats before they can cause damage. They also provide valuable information to improve security and help organizations understand how well they're protecting themselves against attacks, creating a good understanding of cybersecurity risks to help develop better defenses.