Useful Semgrep Links

[github-learning-lab[bot]]

This issue collects various links to useful Semgrep resources and documentation in one place so you can reference it if you ever get stuck.

• semgrep.dev - Semgrep's home page
  • @returntocorp/semgrep - Semgrep's source code on GitHub
• Semgrep Registry - Home of Semgrep's free, out-of-the-box rules (that is, security checks), written by r2c and the community.
  • These rules are grouped into "rulesets" that collect related functionality, like rules that check for secrets, target specific languages (e.g. javascript) or frameworks (e.g. django), or even entire vulnerability classes (e.g. xss or insecure transport).
  • @returntocorp/semgrep-rules - The source code of Semgrep's rules on GitHub.
  • Note that the Registry has more rules than what's just in the returntocorp/semgrep-rules repo, as the Registry includes Semgrep rules from other community repos, like NodeJSScan or Go rules by Damian Gryski.
• Semgrep Playground - Write and share Semgrep rules right from your browser, no installation required!

Rule Writing

There's a step by step rule writing tutorial here.

If you go to the Playground, you can also click the "Examples" button to view a number of illustrative built-in examples.

And of course, you can also review the over 1,000 rules in @returntocorp/semgrep-rules.

Docs

Semgrep has pretty extensive docs, which you can view here.

Of note:

• Pattern syntax - All of the ways you can match code within one pattern.
• Rule syntax - All of the ways you can combine Semgrep patterns to form more complex queries. For example, looking for code that matches this AND that, or this but NOT that, etc.

Community

Feel free to join the r2c community Slack to ask questions (we're super responsive!) or reach out to us on Twitter (@r2cdev), or send us an email at support@r2c.dev.

[jefQuery]

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[github-learning-lab[bot]]

Great! Now we're going to set up Semgrep scanning every PR via GitHub actions by creating a semgrep.yml.

Though we're going to be using GitHub Actions in this workshop, because Semgrep is nice and portable, easily runnable as a standalone binary or Docker, it's pretty easy to set up Semgrep in pretty much any CI platform under the sun.

See these docs for info about setting up Semgrep in GitLab, Buildkit, CircleCI, or other providers, and see here for more info about Semgrep in CI.

⌨️ Activity: Set up Semgrep in CI

1. On the Projects page, select the "Add CI job to GitHub project" option, and click the "Get started" button.
   1. Semgrep's GitHub App is going to ask for a few, minimal permissions so it can auto-set things up for you (create a PR adding semgrep.yml to repos you want to onboard, etc.).
   2. If you want, you can only add the Semgrep GitHub App to this intro-to-semgrep repo. If you want to add more repos, you select "All repositories" or hand select a few more. You can always update this later via your GitHub profile Installed Applications settings.
2. After you've authorized the Semgrep GitHub App, navigate back to the Projects page, click the "Refresh projects from GitHub button", and then click the "Add CI job" button next to the intro-to-semgrep repo row.
3. On the next page, click the "Commit file" button, then follow the instructions for setting up a GitHub Secret on the intro-to-semgrep repo.
   1. Note that we're adding the Secret to just this repo. If you want to run Semgrep across many of your or your org's repos, you probably want to add this Secret at your profile or org level, so you don't have to add it one repo at a time.
4. A Semgrep scan will automatically start. We'll examine the results later, for now, comment on this PR and let's get writing some rules!

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Comment on this Pull Request once you've finished onboarding Semgrep (semgrep.yml GitHub Action) to this repo.