Infrastructure as Code (IaC) Security: 10 Best Practices

IaC is the practice of managing infrastructure with code instead of manual steps or scripts. Rather than clicking through cloud consoles or running ad-hoc commands, you define your setup in configuration files that can be versioned, reviewed, and executed automatically.

Think of it like a recipe for your infrastructure. Clear instructions that consistently produce the same result. IaC templates let you build cloud resources like servers and networks in a repeatable, predictable way.

IaC comes in two flavors: declarative and imperative. 

• Declarative tools (like Terraform, OpenTofu, or AWS CloudFormation) describe the desired end state: You say what you want, and the tool figures out the steps. This works well in the cloud, where consistency and drift detection are key.
• Imperative tools (like Ansible, Chef, or Puppet) give you step-by-step control. They’re great for configuration tasks where order matters — installing software, changing file permissions, or restarting services, especially in hybrid or legacy setups.

In reality, teams often combine both, using Terraform to spin up a VM and Ansible to configure it, for example. IaC brings software engineering practices, like version control, testing, and pull requests, to infrastructure, reducing errors and boosting collaboration, security, and scalability.

When you manage infrastructure through code, you inherit both the benefits and challenges of software development. Just as application code can contain bugs and security vulnerabilities, infrastructure code can contain misconfigurations that create serious security risks. 

A misconfiguration in your infrastructure code can expose entire databases or create network vulnerabilities across all your environments. Obviously, we’d like to avoid that!

IaC security takes a fundamentally different approach to traditional infrastructure security. Instead of securing infrastructure after deployment, it focuses on preventing security issues during the development phase. 

This means scanning infrastructure templates for misconfigurations (IaC scanning), embedding security policies in code (policy as code), and constantly checking that infrastructure remains compliant.

It also shifts team dynamics, as security becomes a partner, not a gatekeeper. By integrating tools and policies into developers’ workflows, secure infrastructure becomes the easy, default path. 

Next, we’ll explore how IaC scanning and policy-as-code help teams catch issues early and maintain compliance automatically.

What is IaC security scanning?

Using a manual approach to reliably detect security issues in infrastructure code is nearly impossible at scale. A typical Terraform configuration might define dozens of resources with hundreds of individual settings, and modern applications often require multiple IaC files across different environments. 

Trying to review every configuration for security best practices manually would slow development to a crawl and still miss subtle vulnerabilities.

IaC security scanning is the automated process of identifying security risks, compliance issues, and misconfigurations in IaC before deployment. It helps teams catch problems early, long before they reach production environments. 

These tools parse your Terraform/OpenTofu files, CloudFormation templates, Kubernetes manifests, and other IaC definitions to identify potential vulnerabilities, compliance violations, and misconfigurations.

Modern scanners can detect hundreds of different issues, such as:

• Publicly accessible S3 buckets and other exposed storage
• Overly permissive IAM roles or security groups
• Hardcoded secrets in code
• Unencrypted resources or disabled logging
• Violations of internal security policies or external compliance standards (e.g., CIS, SOC 2, HIPAA)

They work by maintaining extensive databases of security rules and known vulnerability patterns and then applying those checks during development or as part of your CI/CD pipeline.

The key advantage of IaC security scanning is prevention rather than detection. Instead of alerting you about misconfigurations after they’ve gone live, these tools block unsafe changes before they’re deployed. This:

• Saves development and remediation time
• Reduces security and compliance risk
• Prevents costly production incidents
• Keeps your infrastructure secure by design

In short, IaC security scanning brings security closer to the code, ensuring infrastructure is safe before it ever reaches production.

What is policy as code?

Policy as code transforms static security policies and compliance rules into executable code that enforces standards automatically during infrastructure deployment. Instead of relying on developers to follow security guidelines manually, you define rules that are embedded directly into the infrastructure provisioning process.

For example, imagine your organization has a policy that all S3 buckets must be private and encrypted. Without policy as code, you’d rely on code reviews, documentation, and manual checks to enforce this rule. 

With policy as code, you write a rule that automatically scans your IaC code and blocks any attempt to create a publicly accessible or unencrypted S3 bucket. 

The deployment fails immediately with a clear message: “S3 bucket ‘my-app-data’ violates security policy: public access must be disabled, and encryption must be enabled.”

Popular policy-as-code frameworks include:

• Open Policy Agent (OPA) using the Rego language (See an example: How to Use Open Policy Agent (OPA) with Terraform)
• HashiCorp Sentinel, tailored for Terraform Enterprise
• Checkov and Terrascan, which support custom policies and IaC scanning

The power of policy as code lies in its ability to scale human expertise. A security expert can write a policy once, and it automatically applies to every infrastructure deployment across the organization. This ensures consistent security standards while reducing the manual review burden on security teams.

What are infrastructure drift detection and continuous validation?

Even with perfect IaC templates and strong policies, infrastructure can drift from its intended configuration over time. Someone might manually change a security group rule to troubleshoot an issue, a developer might adjust database settings through the console, or automated processes might modify configurations in ways that weren’t anticipated.

Infrastructure drift detection identifies when your actual deployed infrastructure no longer matches what’s defined in your IaC templates. This matters because drift often means security controls have been bypassed or weakened. 

A manually opened firewall rule or a disabled monitoring service might solve an immediate problem but introduce long-term risks, especially if the security team isn’t aware of the change.

Continuous validation builds on this by actively monitoring your infrastructure against defined security policies and compliance baselines:

• Tools like AWS Config, Azure Security Center, and other cloud-native services continuously assess configuration and alert when resources deviate from approved standards.
• This process helps catch not just drift from IaC, but also violations of broader security or compliance expectations.

The goal isn’t to block all manual changes but to make sure any changes are surfaced, documented, and reviewed for impact. Some teams auto-remediate specific issues; others alert stakeholders to decide whether to update IaC or roll back manual edits. 

When combined, these practices create a strong feedback loop that keeps infrastructure secure, compliant, and in sync with expectations.

The traditional approach to infrastructure security, finding and fixing issues after deployment, is slow, expensive, and ineffective. By the time a misconfiguration is discovered in production, it’s often too late to fix it without coordination headaches, downtime risks, and costly workarounds. 

With IaC security, vulnerabilities are identified and resolved before they ever reach production, shifting security left and making infrastructure both safer and faster to deploy.

Benefits of IaC security include:

• Lower remediation costs – Fixing misconfigurations during code review is practically free. Catching the same issue after deployment can mean downtime, emergency fixes, or even breach costs.
• Scalable, consistent enforcement – Manual processes break at scale. IaC security tools enforce the same rules across all changes, ensuring reliable, repeatable compliance no matter how many deployments happen daily.
• Automatic developer education – Developers get real-time feedback on insecure patterns in their infrastructure code, learning better practices organically as they work.
• Continuous compliance – Instead of scrambling for audits, every infrastructure change is automatically checked against standards, producing a consistent, real-time audit trail.
• Faster, safer deployments – Security becomes part of the pipeline, not a blocker. Automated reviews reduce misconfigurations and ease the burden on operations teams.

Every team should be aware of several common security risks specific to IaC. In a previous article on AWS security risks, we highlighted ten frequent cloud misconfigurations. You’ll notice some overlap here, as many cloud security issues can originate from insecure infrastructure code.

The most common vulnerabilities found in IaC code include:

1. Hard-coded secrets in infrastructure code represent one of the most dangerous IaC security risks. When developers embed database passwords, API keys, or access tokens directly in IaC templates, these secrets can end up in version control systems, state files, or deployment logs.Even if the intention is to replace them later, hardcoded secrets can end up in production and become discoverable by anyone with access to the codebase.
2. Overly permissive IAM policies create unnecessary privilege escalation opportunities. It’s tempting to use wildcards in IAM actions or resources during development to avoid permission errors, but these broad permissions often get deployed to production.
   
   A policy that grants s3:* actions on all resources or allows AssumeRole from any principal can enable attackers to move laterally through your infrastructure once they gain initial access.
3. Publicly exposed resources are among the most frequently discovered vulnerabilities in IaC scans, with varying levels of exposure. S3 buckets configured with public read access, security groups allowing inbound traffic from 0.0.0.0/0, or databases with publicly accessible endpoints, are all common examples.
   
   These misconfigurations usually happen when developers need to test connectivity and choose the most permissive settings to solve immediate problems, but then forget to go back or don’t know they need to.
4. Insecure defaults and misconfigurations occur when infrastructure templates prioritize getting things working over implementing security controls. Resources get deployed without encryption enabled, logging disabled, or backup policies missing.
   
   This is particularly common when using quick-start guides, sample code, or third-party modules that focus on functionality rather than security hardening.
5. Configuration drift between code and deployed infrastructure undermines the entire premise of infrastructure as code.
   
   When teams make manual changes to resources outside of the IaC process, the actual infrastructure no longer matches what’s defined in templates. This creates blind spots (a.k.a shadow IT resources) where security teams either can’t see the resource(s) at all or believe certain controls are in place based on the code, but the deployed reality is different.
6. Excessive permissions in CI/CD pipelines create single points of failure for infrastructure security. When deployment pipelines run with overly broad permissions, administrative access across all cloud accounts, a compromised CI/CD system can lead to complete infrastructure compromise. Pipeline credentials often persist longer than individual user credentials and may have access to multiple environments.
7. Unverified or outdated third-party modules introduce unknown security risks into your infrastructure. Using community modules without a security review, failing to pin module versions, or relying on modules with known vulnerabilities can bring insecure defaults or even malicious code into your infrastructure.This risk is becoming even more common with AI “vibe coding” since third-party modules can get introduced into a project without the team realizing it.
8. Lack of policy enforcement and security guardrails allows insecure configurations to reach production without detection. Without tools like Open Policy Agent, or cloud-native policy services, there’s no automated way to prevent deployments that violate security standards. Teams rely on manual code reviews and hope that reviewers catch security issues.
9. Improper network access controls create unnecessarily broad attack surfaces. Flat network designs, overly permissive security groups, or missing subnet isolation allow attackers to pivot between resources once they gain initial access. Network misconfigurations in IaC are particularly dangerous because they often affect multiple applications and environments.
10. Unprotected Terraform state files expose sensitive infrastructure information to unauthorized access. State files contain detailed configuration data, resource identifiers, and sometimes sensitive values like passwords or private keys.
    
    When stored in unencrypted storage, shared through insecure channels, or accessible to unauthorized users, state files provide attackers with a complete map of your infrastructure and potential credentials for accessing it.

We’ve covered the risks, so now let’s look at how to prevent them. To build secure infrastructure as code, you don’t need to overhaul your entire development process tomorrow or even in the next few weeks.

The key is to start with foundational practices like version control and security scanning, then gradually introduce more as your team matures. A solid starting point is to follow these best practices:

1. Avoid hard-coded secrets – Never embed API keys, passwords, or tokens directly in IaC files. Use secrets management tools (e.g., AWS Secrets Manager, HashiCorp Vault) or environment variables. For a complete guide to Terraform secrets, refer to our guide here. Also, secure your state files, which often contain sensitive data, by encrypting them and storing them in restricted remote backends.
2. Enforce version control and peer-reviewed workflows – Store all infrastructure code in a version-controlled repository. Use pull requests and code reviews to catch misconfigurations early. Implement a branching strategy to manage changes safely across environments.
3. Scan IaC templates for misconfigurations in CI/CD – Use static analysis tools like tfsec, Checkov, or cfn-lint to detect security risks during development automatically. Integrate these scans into your CI/CD pipelines to enforce secure-by-default practices.
4. Apply the least privilege to IAM roles and policies – Avoid overly broad permissions. Define specific IAM policies using least privilege principles. Reuse secure modules or policies to ensure consistency.
5. Use policy as code to enforce security standards – Leverage tools like Open Policy Agent (OPA), Sentinel, or even services like AWS Config with rules to define and enforce security, compliance, and tagging policies as code, automatically blocking or reverting non-compliant changes.
6. Standardize and reuse secure modules – Create or use pre-approved, reusable modules that enforce secure defaults for common resources (e.g., S3 buckets with encryption and logging, VPCs, etc). This reduces room for error and speeds up secure deployments.
7. Encrypt data in transit and at rest by default – Ensure encryption is enabled for all data stores, message queues, and communication paths. Use infrastructure modules that default to encryption and validate that encryption settings remain enabled over time with automated scans
8. Keep dependencies and modules up to date – Use trusted sources for external modules, pin version numbers, and regularly update them to get the latest security patches. You can also look into SBOM tools to track and audit the components used in your infrastructure code, just like you would for application code. This helps avoid introducing vulnerabilities through stale or compromised dependencies.
9. Isolate environments and manage state separately – Use separate configurations and backends for dev, staging, and production. Isolating environments limits the blast radius and enforces cleaner permission boundaries and resource scopes.
10. Monitor for drift and continuously validate infrastructure – Use terraform plan, terraform refresh, or CloudFormation’s native drift detection to ensure your deployed infrastructure matches your IaC definitions. Spacelift can automate this process by continuously monitoring for drift, alerting you when resources diverge from the source code, and even helping you trigger remediation workflows.
    
    Lock down console access, especially in staging and production environments, to reduce unauthorized changes and minimize the risk of Shadow IT.

Choosing the right tools can go a long way in helping you scale IaC security effectively. These tools can help detect misconfigurations, enforce security policies, and automate compliance checks throughout the development lifecycle.

Below is a breakdown of categories and leading infrastructure as code security tools in each, but this is not meant to be a fully comprehensive list:

Static analysis and misconfiguration scanning

These tools analyze IaC templates for issues and/or insecure patterns before deployment.

• Checkov – Scans Terraform, CloudFormation, Kubernetes, and more. Highly customizable with policy support.
• tfsec (Trivy) – Lightweight and fast Terraform security scanner. Integrates well with CI/CD.
• TFLint – Focuses on Terraform linting, including custom rules and plugin support.
• cfn-lint – AWS CloudFormation template linter for structure and best practices.

Policy-as-code and governance

These enforce security, compliance, and operational policies as code.

• Open Policy Agent (OPA) – Policy engine that works with Terraform, Kubernetes, and others
• Sentinel (HashiCorp) – Terraform-specific policy-as-code framework used in Terraform Cloud/Enterprise
• AWS Config Rules – Native AWS rules engine for compliance and drift detection. This works directly against the AWS environment and not so much at the infrastructure code level, but it will help catch issues in production environments.

Secrets management

Tools to securely manage credentials, API keys, and other secrets in IaC workflows.

• AWS Secrets Manager, Azure Key Vault, Google Secret Manager – Managed cloud-native solutions
• HashiCorp Vault – Open-source and enterprise-grade solution for centralized secret storage and dynamic secrets

Drift detection and continuous validation

These IaC tools help ensure that the actual infrastructure matches the IaC definitions over time.

• Terraform (plan, refresh)
• Terraform Cloud / CloudFormation Drift Detection
• AWS Config
• Pulumi (preview)

CI/CD integration

Tools that integrate into pipelines to automate scanning and validation:

• GitHub Actions, GitLab CI, CircleCI, Jenkins – Common CI platforms with IaC scanning integrations
• Atlantis – GitOps tool for Terraform pull request automation
• Spacelift – IaC management platforms with built-in policy enforcement and drift detection

A platform like Spacelift can help you and your organization fully manage cloud resources within minutes. Spacelift is an infrastructure management platform that supports tools like OpenTofu, Terraform, Ansible, Pulumi, Kubernetes, and more. 

Security is one of Spacelift’s biggest priorities, so state-of-the-art security solutions, such as policy as code, encryption, Single Sign-On (SSO), MFA, and private worker pools, are embedded inside the product.

The power of Spacelift lies in its fully automated hands-on approach. Once you’ve created a Spacelift stack for your project, changes to the IaC files in your repository will be applied automatically to your infrastructure. 

Spacelift’s pull request integrations keep everyone informed of what will change by displaying which resources will be affected by new merges. Spacelift also allows you to enforce policies and automated compliance checks that prevent dangerous oversights from occurring.

Spacelift includes drift detection capabilities that periodically check your infrastructure for discrepancies compared to your repository’s state. It can then launch reconciliation jobs to restore the correct state, ensuring your infrastructure operates predictably and reliably.

With Spacelift, you get:

• Policies to control what kind of resources engineers can create, what parameters they can have, how many approvals you need for a run, what kind of task you execute, what happens when a pull request is open, and where to send your notifications
• Stack dependencies to build multi-infrastructure automation workflows with dependencies, having the ability to build a workflow that, for example, generates your EC2 instances using Terraform and combines it with Ansible to configure them
• Self-service infrastructure via Blueprints enabling your developers to do what matters – developing application code while not sacrificing control
• Creature comforts such as contexts (reusable containers for your environment variables, files, and hooks), and the ability to run arbitrary code
• Drift detection and optional remediation

If you want to learn more about Spacelift, create a free account today or book a demo with one of our engineers.

Infrastructure as code enables fast, scalable cloud deployments, but with great power comes great risk. A single misconfiguration in code can expose sensitive data, escalate access, or open doors to attackers.

That’s why IaC security matters from day one. Whether you use Terraform, OpenTofu, Pulumi, or CloudFormation, integrating security early helps catch issues before they scale. It’s about more than avoiding mistakes. It’s about building a secure, reliable foundation for everything that follows.

Effective IaC security includes scanning code, enforcing policies as code, and detecting drift. These measures allow you to catch misconfigurations early, maintain compliance, and automatically enforce best practices.

Common IaC security risks like hard-coded secrets and overly permissive IAM roles often stem from small oversights. 

The takeaway is simple: IaC security is not about slowing down development. With the right practices and tools, teams can ship faster, safer, and with greater confidence.

Frequently asked questions

What are the most common vulnerabilities found in IaC code?

The three most common vulnerabilities in Infrastructure as Code (IaC) are:

1. Hardcoded secrets like API keys in code.
2. Overly permissive IAM roles, often using wildcards.
3. Open security groups, exposing ports to all IPs (0.0.0.0/0).

What is the difference between IaC security and traditional infrastructure security?

IaC security secures infrastructure through code before deployment, enabling automated checks for misconfigurations and policy violations. Traditional infrastructure security protects live systems after setup using runtime tools like firewalls and manual audits. IaC shifts security earlier, making it more scalable and consistent.

What is the biggest benefit of IaC security?

The biggest benefit of IaC security is that it enables early detection and prevention of misconfigurations before infrastructure is deployed. By integrating security checks into CI/CD pipelines, teams can enforce policies, reduce attack surfaces, and maintain compliance automatically, avoiding risks that would otherwise go unnoticed in manual provisioning.