BOLT:Secure GitHub Actions Runtime with 1 line of code

BOLT is an egress-filter and runtime security tool for your GitHub Actions environment.

Usage

Add this step to jobs in your GitHub workflow file(s) to secure your runner:

- name: Setup Bolt
  uses: koalalab-inc/bolt@v1

BOLT is packaged as a GitHub Action, which means you can easily add it to your workflows and start controlling the egress traffic from your pipelines.

Note

Supports both public and private repositories

Why use BOLT?

Ther aftermath of Solarwinds breach has led to an increase in software supply chain attacks.

CI/CD pipelines are the infrastructure of which the software is built, they are the keys to the cloud kingdom, and are high-leverage attack surfaces.

OWASP top 10 CI/CD and CISA+NSA's joint guidance on defending CI/CD are really great starting points to understand the threat vectors surrounding CI/CD. An adaption of the same for GitHub environment would look a little like:

and specifically focussing on the CI runtime threat vectors(and their solution):

BOLT covers both the threat vectors by

1. Transparent Egress filtering mechanism which allows traffic only to trusted domains
2. Detection of actions with Sudo permissions to prevent against file-tampering during build time.

How to use Bolt - Video Introduction

Bolt.by.KoalaLab.mp4

Usage

You can start using Bolt by adding the koalalab-inc/bolt action as the first step in the jobs you want to monitor. The action will install and start the Bolt service on the runner. Checkout the configuration options and defaults here.

- name: Setup Bolt
  uses: koalalab-inc/bolt@v1

Configure

You can configuree the Bolt action using inputs. Here is an example of how to configure the action.

- name: Setup Bolt
  uses: koalalab-inc/bolt@v1
  with:
    mode: 'audit'
    egress_rules: |
      - name: 'Allow GitHub subs'
        destination: '*.github.com'
        action: 'allow'
    disable_passwordless_sudo: 'false'
    default_policy: 'block-all'
    allow_http: 'false'
    graceful: 'true'

Option	Description
mode	Configure the mode of operation for the Bolt gateway. It can be audit or active. Default: audit
egress_rules	A list of custom egress rules to be applied. Default: [].
disable_passwordless_sudo	Whether to disable passwordless sudo or not. Default: false
allow_http	Whether to allow non-secure HTTP requests or not. Default: false
default_policy	It can be either block-all or allow-all. Default: block-all
graceful	Whether to gracefully fail in case of unsupported platforms or not. Default: true

Custom Egress Policy

You can define custom egress rules to control the egress traffic from your pipelines. Here is an example of how to define custom egress rules.

In audit mode, the Bolt gateway will log the egress traffic as per the defined rules. In active mode, the Bolt gateway will enforce the defined rules.

Egress rule options: | Option | Description | ---------------------------------|--------------------------------- | name | A name for the rule | | destination | The destination domain or IP address. * wilcard is supported in destination. | | action | The action to be taken. It can be allow or block |

It is an ordered list of rules. The first rule that matches the destination will be applied.

- name: Setup Bolt
  uses: koalalab-inc/bolt@v1
  with:
    mode: 'audit'
    default_policy: 'block-all'
    allow_http: 'false'
    egress_rules: |
      - name: 'Allow GitHub subdomains'
        destination: '*.github.com'
        action: 'allow'
      - name: 'Block api subdomain'
        destination: 'api.example.com'
        action: 'block'
      - name: 'Allow other subdomains'
        destination: '*.example.com'
        action: 'allow'

Report in workflow logs

Once the job is over, bolt will add a egress traffic report to the job summary. The report will show the egress traffic and the rules that were applied. A sample report is shown below.

---

⚡ Egress Report - powered by Bolt

🛠️ Bolt Configuration

Mode	audit
Allow HTTP	false
Default Policy	block-all

📝 Egress rules

- destination: google.com
  action: block
  name: Block Google
- destination: ifconfig.me
  action: allow
  name: Allow ifconfig.me

Egress Traffic

NOTE: Running in Audit mode. Unknown/unverified destinations will be blocked in Active mode.

🚨 Unknown Destinations

Destination	Scheme	Rule	Action
www.google.com	https	Default Policy - block-all	Unknown Destination

✅ Known Destinations

Destination	Scheme	Rule	Action
github.com	https	Reqd by Github Action	✅
pipelinesghubeus6.actions.githubusercontent.com	https	Reqd by Github Action	✅
results-receiver.actions.githubusercontent.com	https	Reqd by Github Action	✅
ifconfig.me	https	Allow ifconfig.me	✅
api.github.com	https	Reqd by Github Action	✅

View detailed analysis of this run on Koalalab!

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This report was generated using this workflow file: bolt-sample.yml

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Note

We have removed SSL inspection features from Bolt. It had some compatibility issues with certain package managers. We will soon release a new version with improved SSL inspection capabilities.

Usage and Limitations

BOLT is available to use for private as well as public repository on GitHub hosted ubuntu runners. Contact us if you want to use BOLT on self-hosted runners.