Preventative controls are utilized in order to avoid facing a certain threat event or at least to reduce its probability. One of the main preventive countermeasures is the regular change of accounts and passwords in the system in order to prevent possible unauthorized access on the part of third parties. Another control is the deployment of email filtering to decrease the inflow of phishing emails.
Detective controls are used to identify existing vulnerabilities, and conducting antivirus scanning is one of the main examples of such countermeasures. Another detective control is the deployment of an intrusion detection system, which is particularly important since it enables the sysadmin to easily establish and prevent possible attacks on the systems.
Responsive controls focus on solving the existing problems, and the most important one is the disconnecting of an infected system. When a computer or other device gets a virus, it is vital for the sysadmin to disconnect it from the network to prevent other devices from being infected with malware. Additionally, quarantining malicious files is another responsive control that helps to remove an infected file and make it unable to infect other ones.