Cloud API security

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In general, 'cloud API ' here means any API which is intended to handle NZ health information and provides or exposes cloud-deployed data or functions.

The primary purpose of a cloud API may be to:

• Expose a specific commercial health information service, or
• Serve as a 'cross-platform' integration of endpoints across diverse cloud services, or
• Proxy for an application or service running in a legacy environment.

Regardless of the intended purpose, cloud APIs generally involve communication between an API provider implementation in as-a-service, shared public infrastructure, an API consumers that send API requests across a public network.

For these reasons, the measures defined below must be taken to mitigate or eliminate risks inherent in cloud API provision and consumption.

Applicability

This standard defines the requirements for all cloud APIs which:

• provide storage and access to NZ health information classified as MEDICAL IN CONFIDENCE per the HISO 10029 standard¹, and
• provide or expose application functionality or services which execute in a commercial cloud computing environment² accessed through public infrastructure.

Requirements

Cloud API designers/developers MUST ensure the implementation achieves all of the following requirements:

Requirement	Interpretation
Require robust authentication and authorisation	OAuth 2.0, SSO with OpenId Connect, request-level authorisation.
Validate all incoming requests	All content of all incoming messages MUST be validated by the API implementation and/or its supporting infrastructure💡
Throttle API requests and establish quotas	Limit request rates to all endpoints that have the potential to consume or commit substantial human, compute or data resources
Log API activity
Depend only on trusted code libraries / packages
Implement a zero-trust model	Do not allow session-based authentication eg. cookies
Filter traffic traversing public networks	WAFs and API gateways to control requests arriving on Internet routes
Specific identity and access management	Set specific policies / permissions that control access to sensitive resources like credentials, keys, configuration etc.

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Further reading

The following are resources are recommended references for those designing and implementing cloud APIs:

• New Zealand Information Security Manual (NZISM)

• Protective Security Requirements (PSR)

• Center for Internet Security (CIS)

• Cloud Security Alliance (CSA)

• CERT NZ Critical Controls.

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Footnotes

1. HISO 10029:2022 Health Information Security Framework ↩

2. e.g. Amazon Web Services, Google Cloud Platform, Microsoft Azure etc. ↩