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Serverless Authorization Best Practices (Gilad David Maayan)


What Is Serverless Authorization?

Authorization is a method of managing access to resources and services in a serverless computing environment. In a serverless architecture, the underlying infrastructure is abstracted away, and the user only pays for the resources consumed during the execution of their code. Serverless authorization is used to control access to these resources, defining who can perform what actions within the serverless environment. This can be done through the use of access control policies and identity management systems, which allow organizations to define fine-grained permissions for different users and systems.


By using serverless authorization, organizations can ensure that their serverless resources are secure and that only authorized users can access them, reducing the risk of unauthorized access and data breaches.


Why Is Serverless Authorization Important?

Serverless authorization is important for several reasons:

Security: Serverless authorization helps to secure the resources and services within a serverless environment, ensuring that only authorized users can access them. This helps to reduce the risk of unauthorized access, data breaches, and other security incidents.

Monitoring: By controlling access to resources and services, serverless authorization provides improved visibility into the operations of a serverless environment, allowing organizations to better understand how resources and services are being used. This information can be used for serverless monitoring purposes, to optimize the environment, identify areas of risk, and make informed decisions about resource allocation.

Compliance: In many industries, such as healthcare and finance, there are strict regulations around access to sensitive data. Serverless authorization enables organizations to meet these regulations by controlling access to resources and data in a fine-grained manner.

Resource Management: Serverless authorization also enables organizations to manage their serverless resources effectively, ensuring that they are being used efficiently and that resources are not being wasted.

Improved User Experience: Serverless authorization can improve the user experience by enabling users to access only the resources they need, reducing the risk of errors and downtime caused by unauthorized access.

Scalability: As organizations scale their serverless environments, serverless authorization helps ensure that access to resources and services remains manageable and secure. By controlling access to resources and data, serverless authorization helps organizations to maintain control as their environments grow and change over time.


Examples of Serverless Authorization

Serverless Authorization in AWS Lambda

AWS Lambda is a serverless compute service provided by Amazon Web Services (AWS) that enables you to run code in response to events without having to manage servers.


There are several ways to implement serverless authorization in AWS Lambda:

IAM Roles: AWS Identity and Access Management (IAM) roles allow you to grant permissions to AWS services and resources, including Lambda functions. You can create an IAM role that has permissions to invoke a Lambda function, and then grant the role to the users or services that are authorized to invoke the function.

API Gateway: API Gateway is a fully managed service that makes it easy to create, publish, maintain, monitor, and secure APIs at any scale. You can use API Gateway to create a REST API that is integrated with your Lambda function. API Gateway provides several options for securing your API, including API keys, OAuth2, and Lambda authorizers. Learn more about API gateways in this in-depth blog post.

Lambda authorizers: Lambda authorizers allow you to use a Lambda function to authenticate and authorize requests before they are passed on to your main Lambda function. Lambda authorizers receive the incoming request and validate the credentials of the user or service that is making the request. If the credentials are valid, the authorizer generates an IAM policy that allows or denies access to the main Lambda function.


Serverless Authorization in Azure Functions

Azure Functions is a serverless compute service provided by Microsoft Azure that enables you to run code in response to events without having to manage servers.


There are several ways to implement serverless authorization in Azure Functions:

Azure Active Directory: Azure Active Directory (AD) is a cloud-based identity and access management service that provides a secure way to manage user identities and access to resources. You can use Azure AD to authenticate users and authorize access to your Azure Functions. Azure AD provides several options for securing access to your functions, including OAuth2, OpenID Connect, and Azure AD Application Roles.

Shared Access Signature (SAS) Tokens: Shared Access Signatures (SAS) tokens allow you to grant temporary access to your Azure Functions. You can create a SAS token that has permissions to invoke a function, and then grant the token to the users or services that are authorized to invoke the function. SAS tokens are typically used in scenarios where you need to provide access to your function from outside Azure, such as from a mobile app or a third-party service.

API Management: Azure API Management is a fully managed service that makes it easy to create, publish, maintain, and secure APIs at any scale. You can use API Management to create a REST API that is integrated with your Azure Functions. API Management provides several options for securing your API, including client certificates, OAuth2, and JWT tokens.


Serverless Authorization Best Practices

Design and Implement Authorization Early in the Development Lifecycle

Planning and implementing authorization should be considered as an early step in the serverless development process. This helps to ensure that security and access control are integrated into the design and functionality of the application from the start, avoiding potential security weaknesses that may arise later on.


For example, you may need to consider the types of applications that will use your serverless functions downstream, what actions they will be able to perform, and what data they will be able to access. You may also need to consider the role-based access control requirements for the serverless application, as well as the need for multi-factor authentication or other security controls.


Implement Authorization Policies

Authorization policies determine who can access what resources in your serverless application. Most serverless applications are developed within serverless runtime platforms like Amazon Lambda, and authorization is typically set up using cloud provider tools, such as Amazon IAM or Amazon Cognito.


Your authorization policies should be implemented consistently throughout your application, and should be based on the attributes and characteristics of your users, such as their role, permissions, and the data they are authorized to access. For example, you may define an authorization policy that allows only administrators to access sensitive data, or that allows users to only perform read-only actions on public data.


It's also important to regularly review and update your authorization policies to ensure they remain relevant and in line with changing security and access control requirements. This can help you to address new security threats and keep your application secure over time.


Decouple Authorization From Authentication

Decoupling authorization from authentication refers to the practice of separating the processes of verifying the identity of a user or integrated system (authentication) and granting access to resources or performing actions (authorization) within your serverless application.


This separation helps to improve the security and flexibility of your application, by avoiding the potential for security weaknesses that may arise from linking the two processes. Here is how it works:

In authentication, the focus is on verifying the identity of a user or system, typically by requiring it to provide credentials such as a username and password, or a cryptographic key. The authentication process does not determine what the user is allowed to do or access within the application.

In authorization, the focus is on granting or denying access to resources and actions based on the user's permissions, roles, and other attributes. This process determines what the user is authorized to do within the application, based on the policies and rules defined by the system.


By separating authentication from authorization, you can ensure that access control decisions are made in a consistent and secure manner, independent of the mechanism used to verify the user's identity. Additionally, this separation can allow you to change the authentication mechanism used in your application without affecting the authorization logic, and vice versa.


Enforce Least Privilege

The principle of least privilege is based on the idea that users should only have access to the resources and actions that are necessary for them to perform their work, and no more. This helps to reduce the potential for abuse, reduces the risk of insider threats, and ensures that users are only able to perform authorized actions.


For example, a user who only needs to read data from a database should only be granted read access, and not be able to write to or delete data from the database. A user who needs to perform administrative tasks should only be granted the necessary permissions to perform those tasks, and not be able to perform other tasks that they are not authorized to perform.


Enforcing least privilege helps to ensure that your serverless application is secure and that sensitive data is protected from unauthorized access or manipulation. By granting users only the permissions they need, you can reduce the potential attack surface of your application and minimize the risk of security incidents.


Use Claims-Based Authorization

Claims-based authorization is a mechanism for controlling access to resources based on the claims made about a user or integrated system, such as their identity, role, or permissions. These claims are typically issued by an authority, such as an identity provider, and are then used by the resource being protected to make authorization decisions.


In this method, the user is assigned a set of claims that describe their roles, permissions, and other attributes. When the user attempts to access a resource, the authorization mechanism checks the claims contained in the token to determine whether the user has the required permissions to access the resource.


Claims-based authorization provides a flexible and scalable way to manage access control, as it decouples the issuance of claims from the resource being protected, allowing for a separation of concerns. This approach is particularly useful in serverless environments, where there is no direct access to a user's identity or authorization information and authorization needs to be performed in a decentralized manner.


Conclusion

In conclusion, implementing effective authorization in serverless applications is critical to ensure the security and accessibility of your application, while minimizing the risk of security incidents and unauthorized access to sensitive data.


To achieve this, it is recommended to follow best practices such as designing and implementing authorization early in the software development lifecycle, implementing authorization policies, keeping your authorization logic in one place, decoupling authorization from authentication, enforcing least privilege, and using claims-based authorization.



Gilad David Maayan is a technology writer who has worked with over 150 technology companies including SAP, Imperva, Samsung NEXT, NetApp and Check Point, producing technical and thought leadership content that elucidates technical solutions for developers and IT leadership. Today he heads Agile SEO, the leading marketing agency in the technology industry.

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