Skip to content

Instantly share code, notes, and snippets.

Created October 11, 2018 18:27
Show Gist options
  • Save jvehent/9746da895459d9c1eb449a15cb51298e to your computer and use it in GitHub Desktop.
Save jvehent/9746da895459d9c1eb449a15cb51298e to your computer and use it in GitHub Desktop.

Risk Management

  • The service must have performed a Rapid Risk Assessment and have a Risk Record bug
  • The service must be registered via a New Service issue


  • Access and application logs must be archived for a minimum of 90 days
  • Use Modern or Intermediate TLS
  • Set HSTS to 31536000 (1 year)
    • strict-transport-security: max-age=31536000
    • If the service is not hosted under, it must be manually added to Firefox's preloaded pins. This only applies to production services, not short-lived experiments.
  • If service has an admin panels, it must:
    • only be available behind Mozilla VPN (which provides MFA)
    • require Auth0 authentication


  • Ensure your code repository is configured and located appropriately:
    • Application built internally should be hosted in trusted GitHub organizations (mozilla, mozilla-services, mozilla-bteam, mozilla-conduit, mozilla-mobile, taskcluster). Sometimes we build and deploy applications we don't fully control. In those cases, the Dockerfile that builds the application container should be hosted in its own repository in a trusted organization.
    • Secure your repository by implementing Mozilla's GitHub security standard.
  • Sign all release tags, and ideally commits as well
    • Developers should configure git to sign all tags and upload their PGP fingerprint to
    • The signature verification will eventually become a requirement to shipping a release to staging & prod: the tag being deployed in the pipeline must have a matching tag in git signed by a project owner. This control is designed to reduce the risk of a 3rd party GitHub integration from compromising our source code.
  • enable security scanning of 3rd-party libraries and dependencies
  • Keep 3rd-party libraries up to date (in addition to the security updates)
  • Integrate static code analysis in CI, and avoid merging code with issues
    • Javascript applications should use ESLint with the Mozilla ruleset
    • Python applications should use Bandit
    • Go applications should use the Go Meta Linter
    • Use whitelisting mechanisms in these tools to deal with false positives

Dual Sign Off

  • Services that push data to Firefox clients must require a dual sign off on every change, implemented in their admin panels
    • This mechanism must be reviewed and approved by the Firefox Operations Security team before being enabled in production


  • Publish detailed logs in mozlog format (APP-MOZLOG)
    • Business logic must be logged with app specific codes (see FxA)
    • Access control failures must be logged at WARN level

Web Applications

  • Must have a CSP with
    • a report-uri pointing to the service's own /__cspreport__ endpoint
    • web API responses should return default-src 'none'; frame-ancestors 'none'; base-uri 'none'; report-uri /__cspreport__ to disallowing all content rendering, framing, and report violations
    • if default-src is not none, frame-src, and object-src should be none or only allow specific origins
    • no use of unsafe-inline or unsafe-eval in script-src, style-src, and img-src
  • Third-party javascript must be pinned to specific versions using Subresource Integrity (SRI)
  • Web APIs must set a non-HTML content-type on all responses, including 300s, 400s and 500s
  • Set the Secure and HTTPOnly flags on Cookies, and use sensible Expiration
  • Make sure your application gets an A+ on the Mozilla Observatory
  • Verify your application doesn't have any failures on the Security Baseline.
    • Contact secops@ or ping 'psiinon' on github to document exceptions to the baseline, mark csrf exempt forms, etc.
  • Web APIs should export an OpenAPI (Swagger) to facilitate automated vulnerability tests

Security Features

  • Authentication of end-users should be via FxA. Authentication of Mozillians should be via Auth0/SSO. Any exceptions must be approved by the security team.
  • Session Management should be via existing and well regarded frameworks. In all cases you should contact the security team for a design and implementation review
    • Store session keys server side (typically in a db) so that they can be revoked immediately.
    • Session keys must be changed on login to prevent session fixation attacks.
    • Session cookies must have HttpOnly and Secure flags set and the SameSite attribute set to 'strict' or 'lax' (which allows external regular links to login).
    • For more information about potential pitfalls see the OWASP Session Management Cheat Sheet
  • Form that change state should use anti CSRF tokens. Anti CSRF tokens can be dropped for internal sites using SameSite session cookies where we are sure all users will be on Firefox 60+. Forms that do not change state (e.g. search forms) should use the 'data-no-csrf' form attribute.
  • Access Control should be via existing and well regarded frameworks. If you really do need to roll your own then contact the security team for a design and implementation review.
  • If you are building a core Firefox service, consider adding it to the list of restricted domains in the preference extensions.webextensions.restrictedDomains. This will prevent a malicious extension from being able to steal sensitive information from it, see bug 1415644.


  • All SQL queries must be parameterized, not concatenated
  • Applications must use accounts with limited GRANTS when connecting to databases
    • In particular, applications must not use admin or owner accounts, to decrease the impact of a sql injection vulnerability.

Common issues

  • User data must be escaped for the right context prior to reflecting it
    • When inserting user generated html into an html context:
      • Python applications should use Bleach
      • Javascript applications should use DOMPurify
  • Apply sensible limits to user inputs, see input validation
    • POST body size should be small (<500kB) unless explicitly needed
  • When managing permissions, make sure access controls are enforced server-side
  • If caching is used then make sure that any data cached does not incorrectly allow allow access to data protected by access control
  • If handling cryptographic keys, must have a mechanism to handle quarterly key rotations
    • Keys used to sign sessions don't need a rotation mechanism if destroying all sessions is acceptable in case of emergency.
  • Do not proxy requests from users without strong limitations and filtering (see Pocket UserData vulnerability). Don't proxy requests to link local, loopback, or private networks or DNS that resolves to addresses in those ranges (i.e.,,,,,,
  • Do not use target="_blank" in external links unless you also use rel="noopener noreferrer" (to prevent Reverse Tabnabbing)
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment