Terrascan

Introduction

Terrascan is a static code analyzer for Infrastructure as Code. Terrascan allows you to:

• Seamlessly scan infrastructure as code for misconfigurations.
• Monitor provisioned cloud infrastructure for configuration changes that introduce posture drift, and enables reverting to a secure posture.
• Detect security vulnerabilities and compliance violations.
• Mitigate risks before provisioning cloud native infrastructure.
• Offers flexibility to run locally or integrate with your CI\CD.

Resources

• To try Terrascan in your browser, see the Terrascan Sandbox https://www.tenable.com/terrascan

• To learn more about Terrascan's features and capabilities, see the documentation portal: https://runterrascan.io

Key features

• 500+ Policies for security best practices
• Scanning of Terraform (HCL2)
• Scanning of AWS CloudFormation Templates (CFT)
• • Scanning of Azure Resource Manager (ARM)
• Scanning of Kubernetes (JSON/YAML), Helm v3, and Kustomize
• Scanning of Dockerfiles
• Support for AWS, Azure, GCP, Kubernetes, Dockerfile, and GitHub
• Integrates with docker image vulnerability scanning for AWS, Azure, GCP, Harbor container registries.

Quick Start

1. Install
2. Scan
3. Integrate

Step 1: Install

Terrascan supports multiple ways to install and is also available as a Docker image.
See Terrascan's releases page for the latest version of builds in all supported platforms. Select the correct binary for your platform.

Install as a native executable

  curl -L "$(curl -s https://api.github.com/repos/tenable/terrascan/releases/latest | grep -o -E "https://.+?_Linux_x86_64.tar.gz")" > terrascan.tar.gz
  tar -xf terrascan.tar.gz terrascan && rm terrascan.tar.gz
  sudo install terrascan /usr/local/bin && rm terrascan
  terrascan

Install on ArchLinux / Manjaro via AUR

ArchLinux and Manjaro users can install by:

yay -S terrascan

Install via brew

Homebrew users can install by:

$ brew install terrascan

Docker image

Terrascan is also available as a Docker image and can be used as follows

$ docker run tenable/terrascan

Refer to documentation for information.

Step 2: Scan

To scan your code for security issues you can run the following (defaults to scanning Terraform).

$ terrascan scan

Note: Terrascan will exit with an error code if any errors or violations are found during a scan.

List of possible Exit Codes

Step 3: Integrate with CI\CD

Terrascan can be integrated into CI/CD pipelines to enforce security best practices.
Please refer to our documentation to integrate with your pipeline.

Terrascan Commands

You can use the terrascan command with the following options:

$ terrascan
Terrascan

Usage:
  terrascan [command]

Available Commands:
  help        Help about any command
  init        Initialize Terrascan
  scan        Detect compliance and security violations across Infrastructure as Code.
  server      Run Terrascan as an API server
  version     Terrascan version

Flags:
  -c, --config-path string   config file path
  -h, --help                 help for terrascan
  -l, --log-level string     log level (debug, info, warn, error, panic, fatal) (default "info")
  -x, --log-type string      log output type (console, json) (default "console")
  -o, --output string        output type (human, json, yaml, xml) (default "human")

Use "terrascan [command] --help" for more information about a command.

Policies

Terrascan policies are written using the Rego policy language. Every rego includes a JSON "rule" file which defines metadata for the policy.
By default, Terrascan downloads policies from Terrascan repositories while scanning for the first time. However, if you want to download the latest policies, you need to run the Initialization process. See Usage for information about the Initialization process.

Note: The scan command will implicitly run the initialization process if there are no policies found.

Docker Image Vulnerabilities

You can use the --find-vuln flag to collect vulnerabilities as reported in its registry as part of Terrascan's output. Currently Terrascan supports Elastic Container Registry (ECR), Azure Container Registry, Google Container Registry, and Google Artifact Registry.

The --find-vuln flag can be used when scanning IaC files as follows:

$ terrascan scan -i <IaC provider> --find-vuln

For more information and explanation of how to setup your environment to authenticate with the registry's APIs see the usage documentation.

Customizing scans

By default, Terrascan scans your entire configuration against all policies. However, Terrascan supports granular configuration of policies and resources.

Read more about in-file instrumentation and the config file on our documentation site.

For now, some quick tips:

• Exclude a particular policy for a specific resource.
• Manually configure policies to be suppressed or applied globally from a scan across all resources or, for just a particular resource.

How to exclude a policy while scanning a resource

You can configure Terrascan to skip a particular policy (rule) while scanning a resource. Follow these steps depending on your platform:

Terraform

Use Terraform scripts to configure Terrascan to skip rules by inserting a comment with the phrase "ts:skip=<RULENAME><SKIP_REASON>". The comment should be included inside the resource as shown in the example below.

Kubernetes

In Kubernetes yamls, you can configure Terrascan to skip policies by adding an annotation as seen in the snippet below.

How to include or exclude specific policies or resources from being scanned

Use the Terrascan config file to manually select the policies which should be included or excluded from the entire scan. This is suitable for edge use cases.
Use the "in-file" suppression option to specify resources that should be excluded from being tested against selected policies. This ensures that the policies are skipped only for particular resources, rather than all of the resources.

Sample scan output

Terrascan's default output is a list of violations present in the scanned IaC. A sample output:

Building Terrascan

Terrascan can be built locally. This is helpful if you want to be on the latest version or when developing Terrascan. gcc and Go 1.19 or above are required.

$ git clone git@github.com:tenable/terrascan.git
$ cd terrascan
$ make build
$ ./bin/terrascan

To build your own docker, refer to this example (Alpine Linux):

FROM golang:alpine AS build-env

RUN apk add --update git

RUN git clone https://github.com/tenable/terrascan && cd terrascan \
  && CGO_ENABLED=0 GO111MODULE=on go build -o /go/bin/terrascan cmd/terrascan/main.go

Developing Terrascan

To learn more about developing and contributing to Terrascan, refer to the contributing guide.

Code of Conduct

We believe having an open and inclusive community benefits all of us. Please note that this project is released with a Contributor Code of Conduct. By participating in this project you agree to abide by its terms.

License

Terrascan is licensed under the Apache 2.0 License.

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