The key theme for protecting IT systems from unauthorised access is to offer multiple layers of protection in terms of people, technology and physical environment. This is known as defence-in-depth when referring to technology, separation-of-concerns when referring to people and compartmentalization when referring to the physical environment. Ultimately all these techniques resemble lamination as applied to bulletproof glass or car windshields where multiple layers of different materials are used each with different physical characteristics of strength, hardness and brittleness which are stronger in a composite form.
Defence in depth is the use of different technologies to offer layers of protection which protect some aspect of the system such as vulnerable protocols, incorrect content, hard to resolve bugs or enabling a single person to compromise the entire system. Such technologies are firewalls (web, layer-7 or network), DMZs (network zones between two firewalls), content inspecting proxies (anti-malware and data loss prevention) and Virtual Private Networks. They work with IDAM (Identity and Access Management) solutions which also include authorisation, authentication, auditing and logging.
Separation of concerns for people involves the dividing roles between developers, administrators (including DevOps) and security operations staff. The developers design and write code which is turn deployed and managed by administrations and the previous two roles are monitoring by security operations staff. The logging and monitoring provided by the IDAM solutions needs de-duplication, correlation and analysis for behavioural changes to avoid intrusion and infiltration by new techniques (zero day threats) which emerge or are deliberately engineered to overcome the defence in depth solutions. The people aspects of security need a strong security policy, good background checks on candidates, regular training against social engineering and a culture of continuous improvement.
Physical security is still very important aspect of the overall security defence regime and technologies such as strong encryption only mitigates the risks and does not end them. Strongrooms, multiple doors, biometric security, multiple physical sites, CCTV, intrusion detection alarms and in some cases TEMPEST/SCIF techniques are the foundation of good information management. Managing and monitoring physical security in the same way as digital security is paramount to achieving the right level of control. Cloud environments enable the shift some of this responsibility to third parties for Storage, Compute, Network and Backup who are constantly improving through achieving ISO27001, PCI-DSS, HIPAA and FedRAMP certification which benefits all their customers.
Technology security lamination using different technologies/techniques/people at each layer provides the best approach to meet the challenge of continual improvement in the arms race that is Cyber-Security.