Infrastructure as a Service (IaaS) is a cloud model where the provider supplies the underlying compute, storage, networking, and virtualization layer, while the customer configures and secures the operating systems, applications, identity controls, and much of the data layer. Compared with SaaS or PaaS, IaaS gives teams more flexibility, but also more operational responsibility.
In cyber security, IaaS matters because many attacks succeed through customer-managed mistakes rather than provider failure. Exposed management interfaces, weak credentials, overly permissive security groups, unpatched virtual machines, and misconfigured storage are common ways IaaS environments get abused. Defenders use least privilege, hardened images, continuous configuration review, logging, and network segmentation to reduce that risk. The key idea is shared responsibility: the cloud vendor secures the platform, but the customer must secure what they build on it.