Essential security for everyone: Building a secure AWS foundation
In this post, I will show you how teams of all sizes can gain access to world-class security in the cloud without a dedicated security person in your organization. I look at how small teams can build securely on Amazon Web Services (AWS) in a way that’s cost effective and time efficient. I show you the key elements to create a foundation with good security controls, and how you can then use that foundation as a base to build a secure workload upon. In this post, I will also share a lab guide to get you started today. It may look like a lot of work but I ran this as a day-long workshop across Australia in 2019 reaching many start-ups and small businesses. The majority of them implemented the guide by mid-afternoon.
Many large organizations run their regulated workloads on AWS and customers of all sizes have the same security controls available to them. These large organizations have gone through a rigorous process to ensure that the right security controls are available to them. If you go to the AWS Startups Blog, you can read the story of two Australian customers and their journeys to set up a secure foundation on AWS: Tic:Toc, an Australian scaleup in the financial services industry and FYI, a start-up with their document and process management system for accounting practices.
The Well-Architected Framework has been developed to help cloud architects build secure, high performance, resilient, and efficient infrastructure for their applications. Based on five pillars—operational excellence, security, reliability, performance efficiency, and cost optimization—the Framework provides a consistent approach for customers and partners to evaluate architectures and implement designs that will scale over time. In this post, I will discuss the key areas from the security pillar to help you build a secure foundation. These areas are:
- Security foundations. You can use an AWS account as a coarse boundary for isolating resources and use cross-account roles to share common infrastructure. Protect your AWS accounts and use tools like AWS Control Tower to help you get started quickly.
- Identity and access management. Be deliberate about who has access to what.
- Detection. Start with the implementation of baseline logging and monitoring. Do this in a way that’s implemented automatically so it is scalable. When incidents occur, this will help to ensure that basic log data is in place to aid your investigations. Configure alerts for key events and define your response plan so you are prepared to take action.
- Infrastructure and data protection. Apply defense in depth, starting with the features that AWS provides you, to help build a secure application.
- Incident response. Ensure your team is prepared to respond to incidents by educating your team, creating a response plan, simulating scenarios so your team knows what to do before it happens and iterating to improve your plan.
Small teams want to move fast and deliver value. To support that, you want to build a secure foundation. This post focuses on the key initial steps to help you achieve that. To help guide you through the content in this post and implement your foundation faster, we have a Quick Steps to Security Success quest in our Well-Architected Labs.
With a strong foundation in place to support your workload, you can look at how to build securely on top of it. Security is part of every feature, not a separate feature to be implemented later. Teams need to be comfortable with the idea that a feature isn’t complete just when it’s tested and in production. Adjust your culture to think of complete as meaning tested and secure in production.
An AWS account is a boundary within which resources are deployed. You can open multiple AWS accounts for different purposes. For example, to separate different applications you operate by splitting different workloads across multiple environments in different accounts, to provide developer sandbox accounts or to isolated resources such as a security account. A workload is a collection of systems and applications to meet a specific business objective and could be a useful guide for determining what needs to be deployed into separate accounts. From a security point of view, being able to use an AWS account as a boundary helps isolate different parts of your workloads. The account boundary acts as a coarse isolation boundary and you have to be deliberate about how you allow access to resources in it. For human access, this can form a basis for providing least privilege access – an IAM best practice for ensuring that users only have permissions required to fulfil their tasks.
A best practice is to keep users away from data – least privilege could start with not providing access to the production environment. One way to achieve this is to create a separate account for your production workload and ensure that all regular operations are performed at a distance through tools such as pipelines or ticketing systems. Where human access is essential, only grant temporary human access for a fixed period of time. In addition to limited IAM policies, you can give people access only to AWS accounts containing the workload they need access to. For machine-to-machine access you can apply the same concepts and use cross-account access.
At a minimum, it’s a best practice to have a separate organizational management account that’s only used to establish controls across your set of accounts and for configuring identity and access management within your organization. The same identity configuration is then used across accounts. Also, set up a dedicated account for logging to more securely store data such as audit logs. To increase security, create an audit account that has read-only access to the logs and other accounts used by your security team. Then create different accounts for different environments and workloads.
The easiest way to get started creating and organizing accounts is to use AWS Control Tower, which will set up a separated logging and audit account, an AWS Single Sign-On (AWS SSO) directory—which supports identity federation with SAML 2.0—as well as a few basic guardrails. AWS SSO can also give users a single view of all the accounts and roles within those accounts that they have access to. AWS Control Tower also includes a basic account-creation tool—the Account Factory—that you can use to create additional accounts within your AWS account structure.
Guardrails are an important mechanism that customers can implement to help maintain security in the cloud. AWS Control Tower provides two types of guardrails: preventive and detective.
Preventive guardrails are designed to prevent users from performing certain actions; for example, preventing a user from disabling security logging. You can implement preventative guardrails through AWS Control Tower, which provides a feature of AWS Organizations called Service Control Policies (SCP) that you can use to set the maximum boundary for what is allowed in an account. These guardrails are either enforced or disabled.
Detective guardrails look at the state of resources in an account using AWS Config rules and indicate if resources are compliant to those rules or not. For example, looking for Amazon Simple Storage Service (Amazon S3) buckets that are publicly accessible. If you need to have data publicly available, be deliberate about how you do it.
AWS Control Tower has a number of mandatory guardrails that are necessary for the operation of AWS Control Tower as well as a number of strongly recommended and elective guardrails. The strongly recommended and elective guardrails help to ensure that you’re building a strong security posture as soon as you enable them.
There is no additional charge to use AWS Control Tower. However, when you set up AWS Control Tower, you will begin to incur costs for AWS services configured to set up your landing zone and mandatory guardrails. For further details see the AWS Control Tower pricing.
Identity and access management
Identity forms the basis of validating that users are who they say they are and how you give them permission to operate in your environment.
When you sign up for an AWS account, the first login you receive is the root user credentials. The root user credentials are very powerful and allows full access to all resources in the account. It’s critical that you protect your root account from unauthorized access, starting with multi-factor authentication. Multi-factor authentication uses a password (something you know) plus something you have (such as a one-time key or a hardware token) to create a more secure login. After you set up multi-factor authentication, both factors are required to access the root account. After that, use the root account only in emergencies, not in day-to-day operations. Moving from using the root account to using centralized identities allows you to manage your identities centrally and tie every action taken in your environment back an individual. The most effective way to enable connecting all actions to individual users is through federation.
Federation lets you reuse your existing identities, such as those you have in your organization’s identity directory. When a user joins your organization, the first thing you’re likely to do is to give them an identity (so they can do things like access your email systems) and when they leave, you would remove that identity and therefore the access. By federating your AWS accounts with your existing identity directory, you can use the same mechanisms that are tied to your business processes to provide AWS access. Using tools like AWS Single Sign-On (AWS SSO) enables you to quickly federate access for your users and maintain a mapping of the AWS IAM roles (an identity with specific permissions that can be assigned to or assumed by other identities) they have access to across accounts in your organization. If you don’t have an existing identity store you can still achieve a central identity store by using the built-in provider in AWS SSO. When you are assigning permissions, be deliberate with what access you give different users. Ensure that you’re creating and assigning roles based on least privilege—giving only as much access as users need to perform their tasks.
IAM is a feature of your AWS account provided at no additional charge and AWS SSO is offered at no extra charge. Implementing SSO is a low effort way to build a strong identity foundation. If you’ve been operating for a while on AWS, you should perform an audit of your existing AWS Identity and Access Management (IAM) users with a goal to move to a centralized model. An audit of your IAM resources (and centralized identities) will help you to understand who has access to your AWS environment, clear unused credentials, and check that users are assigned permissions that are relevant for their role. IAM access advisor will allow you to see when services were last accessed. Tools such as the IAM Access Analyzer will help you identify the resources in your organization and accounts, such as Amazon S3 buckets or IAM roles, that are shared with an external entity. At the same time, make sure that your account contacts are up to date so that you don’t miss any important information from AWS. You can update these details under AWS billing and management in the console.
After some baseline controls are in place, you need to add controls to ensure that you are aware of what is happening in the environment and that actions are logged. To help you with governance, compliance and auditing your AWS environment you can configure AWS CloudTrail. A CloudTrail log shows you who attempted to take what actions against resources in your AWS account and if the action was allowed or denied. Having a secure store of these logs provides you with an audit history of who did what in your environment. AWS Control Tower configures a secure log store for you in the logging account.
Amazon GuardDuty is a security service that uses intelligent threat detection to alert you to unusual activity in your environment. GuardDuty uses CloudTrail logs to alert you to malicious activity and unauthorized behavior in addition to DNS logs and VPC Flow Logs—which are similar to network flow logs—to analyze the behavior of your workload. GuardDuty builds a baseline over time of activity in your account and alerts you when behavior that strays from the baseline is detected. For example, GuardDuty sends an alert when a user tries to escalate their privilege. These events can be configured in Amazon CloudWatch Events for alerting and triggering automatic actions—for example by triggering an AWS Lambda function to disable the user trying to escalate their privilege until you can contact them.
Implementing manual dashboards though Amazon CloudWatch or those provided with detective tools such as Amazon GuardDuty can give you a clear idea of what’s happening in your environment, but you should also configure alerting for key events. An initial, temporary way of achieving this could be by creating an Amazon CloudWatch Rule with an Amazon SNS topic as the destination and have your team subscribe their email to the SNS topic. As part of setting up alerts, ensure that there’s a remediation process defined for each alert that includes what action to take when an alert is triggered. In the longer term, as your cloud skills mature, you can evolve this to filter out alerts appropriately and iterate your response and remediation processes.
Having a single view of what’s happening in your infrastructure across all accounts and relevant regions gives you a clear picture of the overall state of your environment. Consider using AWS Security Hub to bring together alerts from GuardDuty, other AWS services such as AWS Inspector (for network availability and common vulnerabilities and exposures analysis), and partner products. Security Hub lets you consolidate findings from multiple sources and normalize them so they are comparable. This allows you to have a single view of where you need to take action and what high priority actions are required. Security Hub also allows you to enable compliance checks on your AWS infrastructure to help you adhere to best practices. A great starting point is AWS Foundational Security Best Practices standard.
Infrastructure and data protection
Build protection in layers and be aware of what features are available in the services that you’re using. Many AWS services include a specific section on security as part of their developer documentation. Before you add an AWS service, read the security section of the documentation and understand what options are available to you. Make sure that you understand the cloud-native AWS security services that integrate with the services you use. AWS Key Management Service integrates with many AWS services to enable encryption at rest. For example, you can enable default encryption for all EBS volumes in a region. AWS Certificate Manager provides public certificates which integrate with Elastic Load Balancing and Amazon CloudFront to encrypt data in transit. Public SSL/TLS certificates provisioned through AWS Certificate Manager are free. You pay only for the AWS resources you create to run your application. You can implement AWS WAF (web application firewall) and AWS Shield to protect your HTTPS endpoints. Where implement services that manage resources, such as Amazon RDS, AWS Lambda, and Amazon ECS, to reduce your security maintenance tasks as part of the shared responsibility model.
Once you have your baseline security controls in place your team needs to be prepared to respond effectively during an incident. This includes designing your incident response goals, educating your team and preparing to respond. Simulating events helps the team to learn your processes and tools. Always iterate to improve the process for the future. As a start, consider using the GuardDuty finding types as the basis for what you should be able to respond to. Have a look through the finding types, identify which findings are most applicable and write a runbook outlining the steps on how you would respond. For each finding type, test your response process. In doing so your team will ensure they have the right tools available, the right emergency access, and know who they need to escalate to and collaborate with. By simulating your response process, your team becomes practiced in how to respond and will reduce the time to recovery if an incident should occur.
When comfortable with the process, automate it. For example, create a Lambda function to perform remediation without you having to wake up in the middle of the night to take action. This can be built up over time as you build a baseline of events. Spending some time thinking through priority events for your environment will help you develop a playbook to respond to them. When you’re comfortable with what incident responses you need, you can automate those responses so remediation is triggered when an event occurs, though you may also want a human to verify before triggering a potentially impactful response.
For example, one of the GuardDuty finding types identifies when an EC2 instance is querying an IP address that is associated with cryptocurrency-related activity. The suggested remediation is to investigate the instance, create a snapshot, consider stopping and starting a new instance and raise a support case. Your runbook could outline how to do each of those steps or you could use CloudWatch to trigger a Lambda function which will place the instance in an isolated security group with no internet access for investigation later. Further examples of automation can be found in the Getting Hands on with Amazon GuardDuty labs.
In this post, I’ve shown you some of the techniques and services that can be used to build a secure foundation. Build a strong security foundation and have a multi-account strategy that allows you to isolate different workloads within your organization. A strong identity foundation ensures that you know who is doing what in your environment. Logging and monitoring ensures that you are ready to take action. Building security in layers and using the service features available as you build ensures that you’re using the security controls available to all customers on the platform. Be prepared to respond to incidents and regularly practice your response process so your team is ready if an incident should occur.
A secure foundation is just the start. Remember that security is not a separate feature and new features are not complete until they’re tested and securely in production. Build a security culture of continuous improvement, and take action to ensure that you remain secure as you build out your workloads. Iterate to continue to reduce risk. Use the AWS Well-Architected Tool which allows you and your team to review your workload against best practices which can be paired with the Well-Architected labs for hands on learning. As mentioned above, a lab to help you implement the content in this blog post yourself can be found in the Quick Steps to Security Success lab. Don’t forget that you can also read stories from two AWS customers—Tic:Toc and FYI—on the AWS Startups Blog.
If you have feedback about this post, submit comments in the Comments section below. If you have questions about this post, start a new thread on one of the AWS Security, Identity, and Compliance forums or contact AWS Support.
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