Countermeasures are actions taken to minimize, mitigate, or eliminate threats to and vulnerabilities of computer systems. Countermeasures can take several forms depending on the nature and characteristics of the particular threats and how susceptible the system is to vulnerabilities.
Information technology (IT) controls are a type of countermeasure that focuses on actions that can be taken to mitigate or eliminate vulnerabilities, for example, using good programming practices or restricting queries to only specific inputs.
Technical countermeasures, also known as technical surveillance countermeasures (TSCMs), focus on the ability to identify or detect unauthorized electronic emanations as well as physical security vulnerabilities that put infrastructures (physical and electronic) at risk.