Cloud security is the discipline of protecting data, applications, and infrastructure that run on cloud platforms—including SaaS, PaaS, and IaaS environments.

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Main takeaways

• The shared responsibility model defines a clear boundary: cloud providers secure the infrastructure; customers are responsible for securing their data, identities, and configurations.
• Most cloud security incidents are not caused by provider failures—they result from misconfiguration, excessive permissions, and unmanaged access on the customer side.
• SaaS security is a distinct and increasingly critical subset of cloud security, with its own visibility requirements and governance challenges.
• As cloud environments grow more complex, the gap between what organizations think they've secured and what's actually exposed continues to widen.

What is cloud security?

What distinguishes cloud security from traditional IT security isn't the objective—it's the environment. In a cloud environment, there is no fixed perimeter. Resources are distributed, dynamically provisioned, and accessed from anywhere. The controls that worked on-premises—network firewalls, endpoint management, perimeter monitoring—don't translate directly to an environment where the underlying infrastructure is owned and operated by a third party. This flexibility is also the source of cloud security's central challenge: the attack surface is always expanding, and the boundary of what any organization is responsible for securing shifts depending on the service model.

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The shared responsibility model

Cloud security operates under a shared responsibility model: the cloud provider is responsible for securing the underlying infrastructure, and the customer is responsible for securing what they put on top of it.

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In practice, this means:

• Provider responsibility—Physical data center security, network infrastructure, hypervisor security, and the availability of the platform itself.
• Customer responsibility—Data classification, access control, identity management, application configuration, and compliance with data handling requirements.

The boundary shifts depending on the service model. In IaaS, customers manage more of the stack. In SaaS, the provider manages nearly everything except data and access—which is precisely where most security incidents occur.

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Where cloud security incidents actually happen

The cloud provider's infrastructure is rarely the point of failure. The most common causes of cloud security incidents are:

• Misconfiguration—Storage buckets, databases, or APIs exposed to the public internet due to incorrect settings. A leading cause of data breaches across every major cloud platform.
• Excessive permissions—Identities granted more access than they need, often for convenience, that remain in place long after the original use case is gone.
• Unmanaged SaaS—Employees adopting cloud applications outside IT visibility, creating access pathways and data flows that security teams can't monitor or govern.
• Identity attacks—Account takeover, credential stuffing, and token theft targeting the identities that control cloud access.
• Third-party integrations—OAuth connections and API integrations between cloud services that expand the blast radius of any single compromise.

SaaS security as a cloud security challenge

SaaS deserves specific attention within cloud security because the risk profile is different from IaaS or PaaS.

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In SaaS environments, the customer has no visibility into or control over the underlying infrastructure. Security work is entirely focused on the application layer: who has access, what they can do, how configurations are set, and what data is moving through connected integrations.

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This requires a discovery-first approach—understanding the full SaaS estate, including applications IT never sanctioned, before attempting to govern it.

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Learn how Nudge Security provides comprehensive SaaS discovery and governance across your cloud environment →