Gitea: Configuration Hardening

Published by Bobby Lin on September 25, 2022

Below are some of the configurations of Gitea that are useful for security hardening:

Config Reference: https://docs.gitea.io/en-us/config-cheat-sheet/

The more features we disable, the less attack surfaces we will face when using Gitea.

version: "3"

networks:
  gitea:
    external: false

volumes:
  gitea-data:
    driver: local
  gitea-config:
    driver: local

services:
  server:
    image: gitea/gitea@sha256:ef6279e13e223d956bc417f299a3530795afcf79f3af429a5c893262c550a648
    container_name: gitea
    environment:
      - USER_UID=1000
      - USER_GID=1000
      - GITEA__repository__DISABLE_DOWNLOAD_SOURCE_ARCHIVES=true
      - GITEA__repository__DISABLE_HTTP_GIT=true
      - GITEA__repository__repository.upload__ENABLED=false
      - GITEA__server__DISABLE_SSH=true
      - GITEA__security__DISABLE_GIT_HOOKS=true
      - GITEA__security__DISABLE_WEBHOOKS=true
      - GITEA__security__PASSWORD_COMPLEXITY=on
      - GITEA__security__MIN_PASSWORD_LENGTH=10
      - GITEA__attachment__ENABLED=false
      - GITEA__api__ENABLE_SWAGGER=false
      - GITEA__packages__ENABLED=false
      - GITEA__migrations__ALLOWED_DOMAINS=github.com,*.github.com
      - GITEA__repository__MAX_CREATION_LIMIT=0
      - GITEA__security__PASSWORD_HASH_ALGO=argon2
      - GITEA__mirror__DISABLE_NEW_PUSH=true
      - GITEA__service__DISABLE_REGISTRATION=true
      - GITEA__repository__DISABLED_REPO_UNITS=repo.issues, repo.ext_issues, repo.pulls, repo.wiki, repo.ext_wiki, repo.projects
      - GITEA__service__DEFAULT_ALLOW_CREATE_ORGANIZATION=false
      - GITEA__service__DEFAULT_USER_IS_RESTRICTED=true
      - GITEA__repository__DISABLE_MIGRATIONS=true # Set as false when there is new mirror
      - GITEA__mirror__DISABLE_NEW_PULL=true # Set as false when there is new mirror
    restart: always
    networks:
      - gitea
    volumes:
      - gitea-data:/var/lib/gitea
      - gitea-config:/etc/gitea
      - /etc/timezone:/etc/timezone:ro
      - /etc/localtime:/etc/localtime:ro
    ports:
      - "3000:3000"
      - "222:22"

How to integrate Gitea with Okta (Authentication)?

Published by Bobby Lin on September 17, 2022

Start up Gitea

Create a docker.compose.yml file with the latest Gitea rootless image:

version: "3"

networks:
  gitea:
    external: false

services:
  server:
    image: gitea/gitea@sha256:ef6279e13e223d956bc417f299a3530795afcf79f3af429a5c893262c550a648
    container_name: gitea
    environment:
      - USER_UID=1000
      - USER_GID=1000
    restart: always
    networks:
      - gitea
    volumes:
      - ./gitea:/data
      - /etc/timezone:/etc/timezone:ro
      - /etc/localtime:/etc/localtime:ro
    ports:
      - "3000:3000"
      - "222:22"

Run a command to start Gitea as a docker image in your machine:

docker-compose --project-name gitea -f docker.compose.yml up -d
docker ps -a # Check if the containers are running

Go to localhost and you can see that a local instance of Gitea is running.

Okta integration

Create a Web app in Okta:

Configure the redirect URL: http://localhost:3000/user/oauth2/okta/callback

Save the Client Id and Client secret that will be input into Gitea

You must name the authentication to be the same name under the redirect url. In this case, I have name it as okta

http://localhost:3000/user/oauth2/okta/callback

The admin should paste the Client Id and Client secrets from Okta app to the Authentication Sources tab in “Site Administration”.

Test the integration between Gitea and Okta

You will be redirected to Okta for authentication (ensure MFA is enabled preferably with FIDO2)

If this is the first time that you login with Gitea, you will need to fill in your username and email address to create an account.

GH Actions Misconfiguration – causing Command Injection

Published by Bobby Lin on September 16, 2022

Suppose you have a Github Actions script like below:

The script will be triggered when a new issue comment is added to the issue or a comment is edited.

name: GitHub Actions Demo
on:
  issue_comment:
    types: [created, edited]
jobs:
  Explore-GitHub-Actions:
    runs-on: ubuntu-latest
    steps:
      - run: echo "🎉 The job was automatically triggered by a ${{ github.event_name }} event."
      - run: echo "🐧 This job is now running on a ${{ runner.os }} server hosted by GitHub!"
      - run: echo "🔎 The name of your branch is ${{ github.ref }} and your repository is ${{ github.repository }}."
      - run: echo ${{ github.event.comment.body }}

Notice that ${{ github.event.comment.body }} is used in the run step directly? This makes the script vulnerable to Command Injection. Why?

Read this: https://securitylab.github.com/research/github-actions-untrusted-input/#remediation

In this context, someone can inject commands to the GH Action script by adding their payload to the issue comment. The GH Action script is triggered every time there is a new issue comment.

Did you notice we can run echo bye? This is just a simple example but worse scenario can be reverse-shell (if you are using self-hosted GH Runners) or secrets theft.

You can even attack in a stealth mode by deleting the comment immediately once the workflow is triggered.

How to prevent the issue?

Set the github context data in env variable before you use it in the run

[...]
      - env: # Add this
          BODY: ${{ github.event.comment.body }} # Add this
        run: echo "$BODY"

Add a new comment that contains a payload:

You can see the script is interpreting the comment body as string rather than interpolating it as a command to execute.

Month: September 2022