240 lines
19 KiB
Markdown
240 lines
19 KiB
Markdown
<p align="center">
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<picture>
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<source media="(prefers-color-scheme: light)" srcset="images/banner.png" width="400">
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<img alt="Dark Banner" src="images/banner-dark.png" width="400">
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</picture>
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</p>
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<div align="center">
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[](https://stepsecurity.io/?utm_source=github&utm_medium=organic_oss&utm_campaign=harden-runner)
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[](https://api.securityscorecards.dev/projects/github.com/step-security/harden-runner)
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[](https://raw.githubusercontent.com/step-security/harden-runner/main/LICENSE)
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</div>
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## Harden Github-hosted and self-hosted runners
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Harden-Runner provides network egress filtering and runtime security for GitHub-hosted and self-hosted runners.
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Learn how Harden-Runner works through the video below, which shows how it detected a supply chain attack on a Google open-source project.
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<a href="https://youtu.be/Yz72qAOrN9s" target="_blank"><img src="images/case-study-thumbnail1.png" alt="Harden-Runner detected supply chain attack in a Google open-source project" title="This case study video shows how StepSecurity Harden-Runner detected a CI/CD supply chain attack in real-time in Google’s open-source project Flank"></a>
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## 3,000+ open source projects use Harden-Runner
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| [](https://app.stepsecurity.io/github/cisagov/skeleton-generic/actions/runs/7588528684) | [](https://app.stepsecurity.io/github/microsoft/ebpf-for-windows/actions/runs/7587031851) | [](https://app.stepsecurity.io/github/GoogleCloudPlatform/functions-framework-ruby/actions/runs/7576989995) | [](https://app.stepsecurity.io/github/DataDog/stratus-red-team/actions/runs/7446169664) | [](https://app.stepsecurity.io/github/intel/cve-bin-tool/actions/runs/7590975903) | [](https://app.stepsecurity.io/github/kubernetes-sigs/cluster-api-provider-azure/actions/runs/7591172950) | [](https://app.stepsecurity.io/github/nodejs/node/actions/runs/7591405720) | [](https://app.stepsecurity.io/github/aws/aperf/actions/runs/7631366761) |
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| --------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------- |
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| **CISA**<br>[Explore](https://app.stepsecurity.io/github/cisagov/skeleton-generic/actions/runs/7588528684) | **Microsoft**<br>[Explore](https://app.stepsecurity.io/github/microsoft/ebpf-for-windows/actions/runs/7587031851) | **Google**<br>[Explore](https://app.stepsecurity.io/github/GoogleCloudPlatform/functions-framework-ruby/actions/runs/7576989995) | **DataDog**<br>[Explore](https://app.stepsecurity.io/github/DataDog/stratus-red-team/actions/runs/7446169664) | **Intel**<br>[Explore](https://app.stepsecurity.io/github/intel/cve-bin-tool/actions/runs/7590975903) | **Kubernetes**<br>[Explore](https://app.stepsecurity.io/github/kubernetes-sigs/cluster-api-provider-azure/actions/runs/7591172950) | **Node.js**<br>[Explore](https://app.stepsecurity.io/github/nodejs/node/actions/runs/7591405720) | **AWS**<br>[Explore](https://app.stepsecurity.io/github/aws/aperf/actions/runs/7631366761) |
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## Why
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There are two main threats from compromised workflows, dependencies, and build tools in a CI/CD environment:
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1. Exfiltration of CI/CD credentials and source code
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2. Tampering of source code, dependencies, or artifacts during the build to inject a backdoor
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Harden-Runner monitors process, file, and network activity to:
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| | Countermeasure | Prevent Security Breach |
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| --- | ----------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
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| 1. | Monitor and block outbound network traffic at the DNS, HTTPS (Layer 7), and network layers (Layers 3 and 4) to prevent exfiltration of code and CI/CD credentials | To prevent the [Codecov breach](https://github.com/step-security/github-actions-goat/blob/main/docs/Vulnerabilities/ExfiltratingCICDSecrets.md) scenario |
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| 2. | Detect if source code is being tampered during the build process to inject a backdoor | To detect the [XZ Utils](https://www.stepsecurity.io/blog/analysis-of-backdoored-xz-utils-build-process-with-harden-runner) and [SolarWinds incident](https://github.com/step-security/github-actions-goat/blob/main/docs/Vulnerabilities/TamperingDuringBuild.md) scenario |
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| 3. | Detect poisoned workflows and compromised dependencies | To detect [Dependency confusion](https://github.com/step-security/github-actions-goat/blob/main/docs/Vulnerabilities/ExfiltratingCICDSecrets.md#dependency-confusion-attacks) and [Malicious dependencies](https://github.com/step-security/github-actions-goat/blob/main/docs/Vulnerabilities/ExfiltratingCICDSecrets.md#compromised-dependencies) |
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## How
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### GitHub-Hosted Runners
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1. Add the `step-security/harden-runner` GitHub Action to your GitHub Actions workflow file as the first step in each job.
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```yaml
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steps:
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- uses: step-security/harden-runner@63c24ba6bd7ba022e95695ff85de572c04a18142 # v2.7.0
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with:
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egress-policy: audit
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```
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2. In the workflow logs and the job markdown summary, you will see a link to security insights and recommendations.
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<p align="left">
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<img src="images/buildlog1.png" alt="Link in build log" >
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</p>
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3. Click on the link ([example link](https://app.stepsecurity.io/github/step-security/github-actions-goat/actions/runs/7704454287)). You will see a process monitor view of network and file events correlated with each step of the job.
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<p align="left">
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<img src="images/network-events1.png" alt="Insights from harden-runner" >
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</p>
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4. In the `Recommended Policy` tab, you'll find a recommended block policy based on outbound calls aggregated from the current and past runs of the job. You can update your workflow file with this policy, or alternatively, use the [Policy Store](https://docs.stepsecurity.io/harden-runner/how-tos/block-egress-traffic#2-add-the-policy-using-the-policy-store) to apply the policy without modifying the workflow file. From now on, any outbound calls not in the allowed list will be blocked.
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<p align="left">
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<img src="images/recommended-policy1.png" alt="Policy recommended by harden-runner" >
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</p>
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## Hands-On Tutorials
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You can use [GitHub Actions Goat](https://github.com/step-security/github-actions-goat) to try Harden-Runner. You only need a GitHub Account and a web browser.
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Hands-on Tutorials for GitHub Actions Runtime Security:
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1. [Filter Egress Network Traffic](https://github.com/step-security/github-actions-goat/blob/main/docs/Solutions/RestrictOutboundTraffic.md)
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2. [Detect File Tampering](https://github.com/step-security/github-actions-goat/blob/main/docs/Solutions/MonitorSourceCode.md)
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## Support for Self-Hosted Runners and Private Repositories
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Hardening for self-hosted runners and GitHub-hosted runners used in private repositories is supported with a commercial license. Check out the [documentation](https://docs.stepsecurity.io/stepsecurity-platform/billing) for more details.
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- To use Harden-Runner in a `Private` repository, you must install the [StepSecurity Actions Security GitHub App](https://github.com/apps/stepsecurity-actions-security).
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- This is needed to access the GitHub Actions API and to authenticate users to access the insights URL for private repositories.
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- If you use Harden-Runner GitHub Action in a private repository, the generated insights URL is NOT public. Only those who have access to the repository can view it.
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Read this [case study on how Kapiche uses Harden-Runner](https://www.stepsecurity.io/case-studies/kapiche/) to improve software supply chain security in their private repositories.
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### Self-Hosted Actions Runner Controller (ARC) Runners
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> Explore demo workflows using self-hosted ARC Runner and ARC Harden-Runner [here](https://docs.stepsecurity.io/harden-runner/how-tos/enable-runtime-security-arc).
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Actions Runner Controller (ARC) is a Kubernetes operator that orchestrates self-hosted runners for GitHub Actions.
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- Instead of adding the Harden-Runner GitHub Action in each job, you'll need to install the ARC Harden-Runner daemonset on your Kubernetes cluster.
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- Upon installation, the ARC Harden-Runner daemonset monitors all jobs run on the cluster; you do NOT need to add the Harden-Runner GitHub Action to each job for `audit` mode. You do need to add the Harden-Runner GitHub Action to jobs where you want to enable `block` mode.
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- Please email support@stepsecurity.io for instructions on how to install the ARC-Harden-Runner daemonset on your Kubernetes cluster.
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### Self-Hosted VM Runners (e.g. on EC2)
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> Explore demo workflows using self-hosted VM Runners and Harden-Runner [here](https://docs.stepsecurity.io/harden-runner/how-tos/enable-runtime-security-vm).
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- Instead of adding the Harden-Runner GitHub Action in each job, you'll need to install the Harden-Runner agent on your runner image (e.g. AMI). This is typically done using packer or as a post-install step when using the https://github.com/philips-labs/terraform-aws-github-runner project to setup runners.
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- The Harden-Runner agent monitors all jobs run on the VM, both ephemeral and persistent runners are supported; you do NOT need to add the Harden-Runner GitHub Action to each job for `audit` mode. You do need to add the Harden-Runner GitHub Action to jobs where you want to enable `block` mode.
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- Please email support@stepsecurity.io for instructions on how to install the Harden-Runner agent on your self-hosted VM runners. This agent is different than the one used for GitHub-hosted runners.
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## Features at a glance
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For details, check out the documentation at https://docs.stepsecurity.io
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### 📶 View outbound network traffic
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> Applies to both GitHub-hosted and self-hosted runners
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Harden-Runner monitors all outbound traffic from each job at the DNS and network layers
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- After the workflow completes, each outbound call is correlated with each step of the job, and shown in the insights page
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- For self-hosted runners, no changes are needed to workflow files to monitor egress traffic
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- A filtering (block) egress policy is suggested in the insights page based on the current and past job runs
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### 🌐 View outbound HTTPS traffic
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> Applies to GitHub-hosted and self-hosted VM runners
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Harden-Runner can monitor outbound HTTPS requests. This feature is supported with a commercial license.
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- HTTPS events are monitored using eBPF (no MITM proxy is used)
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- If a HTTP PUT/ POST/ PATCH call is made to `github.com` or `api.github.com` hosts to a HTTP Path with a different organization than where the workflow is running, the call is marked as anomalous
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- As of now, only HTTPS calls to `github.com` and `api.github.com` hosts are monitoried.
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<p align="left">
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<img src="images/https-events.png" alt="Policy recommended by harden-runner" >
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</p>
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### ⚠️ Detect anomalous outbound network traffic
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> Applies to both GitHub-hosted and self-hosted runners
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Harden-Runner creates a baseline of outbound traffic for each job during the first few runs that it monitors
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- After the baseline is created, any new outbound destinations are marked as anomalous in the insights page
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- You can view the list of all anomalous outbound network traffic in the `Runtime detections` page on the dashboard
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### 🚦 Filter outbound network traffic to allowed endpoints
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> Applies to both GitHub-hosted and self-hosted runners
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Once allowed endpoints are set in the policy in the workflow file, or in the [Policy Store](https://docs.stepsecurity.io/harden-runner/how-tos/block-egress-traffic#2-add-the-policy-using-the-policy-store)
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- Harden-Runner blocks egress traffic at the DNS (Layer 7) and network layers (Layers 3 and 4)
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- It blocks DNS exfiltration, where attacker tries to send data out using DNS resolution
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- Wildcard domains are supported, e.g. you can add `*.data.mcr.microsoft.com:443` to the allowed list, and egress traffic will be allowed to `eastus.data.mcr.microsoft.com:443` and `westus.data.mcr.microsoft.com:443`
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<p align="left">
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<img src="images/blocked-outbound-call-3.png" alt="Policy recommended by harden-runner" >
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</p>
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### 📁 Detect tampering of source code during build
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> Applies to both GitHub-hosted and self-hosted runners
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Harden-Runner monitors file writes and can detect if a file is overwritten.
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- Source code overwrite is not expected in a release build
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- All source code files are monitored, which means even changes to IaC files (Kubernetes manifest, Terraform) are detected
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- You can enable notifications to get one-time alert when source code is overwritten
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- For self-hosted runners, no changes are needed to workflow files for file monitoring
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<p align="left">
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<img src="images/file-events.png" alt="Policy recommended by harden-runner" >
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</p>
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### 🚫 Run your job without sudo access
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> Applies to GitHub-hosted runners
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GitHub-hosted runner uses passwordless sudo for running jobs.
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- This means compromised build tools or dependencies can install attack tools
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- If your job does not need sudo access, you see a policy
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recommendation to disable sudo in the insights page
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- When you set `disable-sudo` to `true`, the job steps run without sudo access to the GitHub-hosted Ubuntu VM
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### 🔔 Get security alerts
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> Applies to both GitHub-hosted and self-hosted runners
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Install the [StepSecurity Actions Security GitHub App](https://github.com/apps/stepsecurity-actions-security) to get security alerts.
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- Email and Slack notifications are supported
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- Notifications are sent when outbound traffic is blocked or source code is overwritten
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- Notifications are not repeated for the same alert for a given workflow
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## Discussions
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- If you have questions or ideas, please use [discussions](https://github.com/step-security/harden-runner/discussions).
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- For support for self-hosted runners and private repositories, email support@stepsecurity.io.
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- If you use a different CI/CD Provider (e.g. Jenkins, Gitlab CI, etc), and would like to use Harden Runner in your environment, please email interest@stepsecurity.io
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## How does it work?
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### GitHub-Hosted Runners
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For GitHub-hosted runners, Harden-Runner GitHub Action downloads and installs the StepSecurity Agent.
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- The code to monitor file, process, and network activity is in the Agent.
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- The agent is written in Go and is open source at https://github.com/step-security/agent
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- The agent's build is reproducible. You can view the steps to reproduce the build [here](http://app.stepsecurity.io/github/step-security/agent/releases/latest)
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### Self-Hosted Actions Runner Controller (ARC) Runners
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- ARC Harden Runner daemonset uses eBPF
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- You can find more details in this blog post: https://www.stepsecurity.io/blog/introducing-harden-runner-for-kubernetes-based-self-hosted-actions-runners
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- ARC Harden Runner is NOT open source.
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### Self-Hosted VM Runners (e.g. on EC2)
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- For self-hosted VMs, you add the Harden-Runner agent into your runner image (e.g. AMI).
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- Agent for self-hosted VMs is NOT open source.
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## Limitations
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### GitHub-Hosted Runners
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1. Only Ubuntu VM is supported. Windows and MacOS GitHub-hosted runners are not supported. There is a discussion about that [here](https://github.com/step-security/harden-runner/discussions/121).
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2. Harden-Runner is not supported when [job is run in a container](https://docs.github.com/en/actions/using-jobs/running-jobs-in-a-container) as it needs sudo access on the Ubuntu VM to run. It can be used to monitor jobs that use containers to run steps. The limitation is if the entire job is run in a container. That is not common for GitHub Actions workflows, as most of them run directly on `ubuntu-latest`. Note: This is not a limitation for Self-Hosted runners.
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### Self-Hosted Actions Runner Controller (ARC) Runners
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1. Since ARC Harden Runner uses eBPF, only Linux jobs are supported. Windows and MacOS jobs are not supported.
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### Self-Hosted VM Runners (e.g. on EC2)
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1. Only Ubuntu VM is supported. Windows and MacOS jobs are not supported.
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