Use a GitHub App instead
If possible, consider using a GitHub App instead of an OAuth app. In general, GitHub Apps are preferred over OAuth apps. GitHub Apps use fine-grained permissions, give the user more control over which repositories the app can access, and use short-lived tokens. These properties can harden the security of your app by limiting the damage that could be done if your app's credentials are leaked.
Similar to OAuth apps, GitHub Apps can still use OAuth 2.0 and generate a type of OAuth token (called a user access token) and take actions on behalf of a user. However, GitHub Apps can also act independently of a user.
For more information about GitHub Apps, see "About creating GitHub Apps."
For more information about migrating an existing OAuth app to a GitHub App, see "Migrating OAuth apps to GitHub Apps."
Use minimal scopes
Your OAuth app should only request the scopes that the app needs to perform its intended functionality. If any tokens for your app become compromised, this will limit the amount of damage that can occur. For more information, see "Authorizing OAuth apps."
Authorize thoroughly and durably
After signing in a user, app developers must take additional steps to ensure that the user is meant to have access to the data in your system. Each sign in requires fresh checks around their memberships, access, and their current SSO status.
Use the durable, unique id to store the user
When a user signs in and performs actions in your application, you have to remember which user took that action in order to grant them access to the same resources the next time they sign in.
To store users in your database correctly, always use the id of the user. This value will never change for the user or be used to point to a different user, so it ensures you are providing access to the user you intend. You can find a user's id with the GET /user REST API endpoint. See "REST API endpoints for users."
If you store references to repositories, organizations, and enterprises, use their id as well to ensure your links to them remain accurate.
Never use identifiers that can change over time, including user handles, organization slugs, or email addresses.
Validate organization access for every new authentication
When you use a user access token, you should track which organizations the token is authorized for. If an organization uses SAML SSO and a user has not performed SAML SSO, the user access token will not have access to that organization. You can use the GET /user/installations REST API endpoint to verify which organizations a user access token has access to. If the user is not authorized to access an organization, you should prevent their access to organization owned data within your own application until they perform SAML SSO. For more information, see "REST API endpoints for GitHub App installations."
Store user data with organizational and enterprise contexts
Beyond tracking user identity via the id field, you should retain data for the organization or enterprise each user is operating under. This will help ensure you don't leak sensitive information if a user switches roles.
For example:
- A user is in the
Monaorganization, which requires SAML SSO, and signs into your app after performing SSO. Your app now has access to whatever the user does withinMona. - The user pulls a bunch of code out of a repository in
Monaand saves it in your app for analysis. - Later, the user switches jobs, and is removed from the
Monaorganization.
When the user accesses your app, can they still see the code and analysis from the Mona organization in their user account?
This is why it's critical to track the source of the data that your app is saving. Otherwise, your app is a data protection threat for organizations, and they're likely to ban your app if they can't trust that your app correctly protects their data.
Verify a user's access to your app
Your OAuth app can be accessed by users outside your organization or enterprise. If you intend an app to be used only by members of your organization or enterprise, you should check the user's membership status when the user signs in to your app.
To find the list of organizations a user is a member of, you can use the "List organizations for the authenticated user" endpoint. Then you can validate this list against a list of approved organizations for your app. For more information, see "REST API endpoints for organizations."
Note: On GitHub.com, even an OAuth app created by a managed user account or organization with managed users can be accessed by users outside the enterprise.
Secure your app's credentials
With a client secret, your app can authorize a user and generate user access tokens. These tokens can be used to make API requests on behalf of a user.
You must store your app's client secret and any generated tokens securely. The storage mechanism depends on your integrations architecture and the platform that it runs on. In general, you should use a storage mechanism that is intended to store sensitive data on the platform that you are using.
Client secrets
If your app is a website or web app, consider storing your client secret in a key vault, such as Azure Key Vault, or as an encrypted environment variable or secret on your server.
If your app is a native client, client-side app, or runs on a user device (as opposed to running on your servers), you cannot secure your client secret. You should use caution if you plan to gate access to your own services based on tokens generated by your app, because anyone can access the client secret to generate a token.
User access tokens
If your app is a website or web app, you should encrypt the tokens on your back end and ensure there is security around the systems that can access the tokens. Consider storing refresh tokens in a separate place from active access tokens.
If your app is a native client, client-side app, or runs on a user device (as opposed to running on your servers), you may not be able to secure tokens as well as an app that runs on your servers. You should store tokens via the mechanism recommended for your app's platform, and keep in mind that the storage mechanism may not be fully secure.
Use the appropriate token type
OAuth apps can generate user access tokens in order to make authenticated API requests. Your app should never use a personal access token or GitHub password to authenticate.
Make a plan for handling security breaches
You should have a plan in place so that you can handle any security breaches in a timely manner.
In the event that your app's client secret is compromised, you will need to generate a new secret, update your app to use the new secret, and delete your old secret.
In the event that user access tokens are compromised, you should immediately revoke these tokens. For more information, see "REST API endpoints for OAuth authorizations."
Conduct regular vulnerability scans
You should conduct regular vulnerability scans for your app. For example, you might set up code scanning and secret scanning for the repository that hosts your app's code. For more information, see "About code scanning" and "About secret scanning."
Choose an appropriate environment
If your app runs on a server, verify that your server environment is secure and that it can handle the volume of traffic that you expect for your app.
Use services in a secure manner
If your app uses third-party services, they should be used in a secure manner:
- Any services used by your app should have a unique login and password.
- Apps should not share service accounts such as email or database services to manage your SaaS service.
- Only employees with administrative duties should have admin access to the infrastructure that hosts your app.
Add logging and monitoring
Consider adding logging and monitoring capabilities for your app. A security log could include:
- Authentication and authorization events
- Service configuration changes
- Object reads and writes
- User and group permission changes
- Elevation of role to admin
Your logs should use consistent timestamping for each event and should record the users, IP addresses, or hostnames for all logged events.
Enable data deletion
If your app is available to other users, you should give users a way to delete their data. Users should not need to email or call a support person in order to delete their data.