Resilience, backup and recovery

Plan to withstand and recover, not only to prevent

Prevention will sometimes fail, so resilience is the ability to keep essential services running, or restore them quickly, when it does. For critical infrastructure, availability and safety are often the priority. Build continuity and recovery into your design, not as an afterthought.

Protect and test your backups

• Back up critical systems and data on a schedule matched to how much you could afford to lose.

• Keep at least one backup copy offline or otherwise isolated, so ransomware cannot reach it.

• Protect backups with strong access control and encryption, and monitor that they complete.

• Test restores regularly. A backup you have never restored is a hope, not a plan.

Prepare for ransomware and destructive attacks

Assume an attacker may try to encrypt or destroy systems and backups at the same time. Segment networks to limit spread, restrict administrative access, and keep offline recovery media and documented rebuild procedures. Decide in advance who authorises major recovery decisions, and never rely on paying a ransom as a recovery strategy.

Define and exercise your recovery

Set recovery time and recovery point objectives for each essential service, and document the order in which systems must be restored to bring a service back safely. Exercise the plan, including worst-case scenarios where primary systems and staff are unavailable, and refine it after every test and real event.

Useful references

• NCSC: Mitigating malware and ransomware attacks

• CISA: Secure Our World