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Semgrep Rule Variant Creator

Checked
trailofbits·vlatest·security·CC-BY-SA-4.0

This skill generates diverse Semgrep rule variants from a single rule, accelerating code analysis and finding subtle issues effectively.

Repository

Install on your platform

Showing Claude Code. One command installs this skill into any of the agents below.

  1. 1

    Run this in your project

    terminal
    $ npx skills add trailofbits/skills --skill semgrep-rule-variant-creator -a claude-code

  2. Uses the open-source skills CLI and needs Node.js. Add -g to install it for your user instead of this project.

What we know about this skill

Publisher

trailofbits

Taken from the source listing. We haven't verified who controls this account.

Install target

Live repository

Not pinned. Installing fetches whatever the repository holds at the time you run the command.

No human has reviewed this code. The checks below are a static scan of the files at one commit — nobody has run this skill or judged whether it works. A skill runs with whatever access you give your agent, so read the source before you install it.

Automated safety checks

scanned

This skill passed all 6 checks. We read its files at one commit and looked for the things that make a skill dangerous to run — not for whether it works.

  • Declares what it does: passed

    SKILL.md parses and declares a name and a description.

    SKILL.md exists, its frontmatter parses, and it declares a name and a description.

  • No undeclared network calls: passed

    Makes no network calls.

    Every host the skill dials — from its scripts, its config endpoints or the commands it tells the agent to run — is either well-known package and API infrastructure or declared in its own frontmatter. Links in documentation are not counted.

  • No obfuscated payloads: passed

    No encoded or obfuscated payloads.

    No base64, hex or compressed blob is decoded and then executed, and no encoded shell commands.

  • No credential access: passed

    Reads no keys, tokens, keychains or credential files.

    Neither the code nor the SKILL.md instructions read SSH keys, cloud credentials, keychains, token stores, browser cookie databases or dotfiles that hold secrets.

  • No pipe-to-shell installers: passed

    No pipe-to-shell or download-and-run installers.

    No `curl … | sh` pattern, in the code or in the instructions, that runs code fetched at run time.

  • Pinned to a commit: passed

    Scanned trailofbits/skills at 82fe822625.

    The exact upstream commit SHA that was scanned is recorded, so the result refers to specific bytes.

Commit
82fe822625
Manifest
plugins/semgrep-rule-variant-creator/skills/semgrep-rule-variant-creator/SKILL.md
Scanned
5 files, 887 lines
This is a static scan, not a review. It reads the skill's files; it does not run them, and it cannot tell you whether the skill is any good or whether the code does what its description says. A skill runs with whatever access you give your agent.
What each check looks for →

About this skill

What it does

The semgrep-rule-variant-creator skill generates variations of existing Semgrep rules. It allows users to create new, customized rules based on established patterns and logic, facilitating more targeted code analysis. This is useful for adapting security checks to specific project contexts or identifying subtle deviations from coding standards.

When to use it

  • Customizing Security Checks: Adapt a general Semgrep rule to focus on a particular vulnerability within your codebase.
  • Enforcing Coding Standards: Create variations of existing rules to enforce nuanced aspects of your team's coding style guidelines.
  • Extending Existing Rules: Build upon the foundation of established rules to cover new code patterns or technologies.
  • Rapid Prototyping: Quickly generate multiple rule variants for experimentation and comparison.

Key capabilities

  • Rule variation generation
  • Customization of existing Semgrep rules
  • Adaptation for specific project contexts
  • Enforcement of coding standards

Example prompts

  • "Create a variant of the 'C' rule that only flags instances where the variable is used after its initialization."
  • "Generate three variations of the 'SQL injection' rule, each with different levels of strictness."
  • "Modify the existing 'hardcoded_credentials' rule to ignore files in the 'secrets' directory."

Tips & gotchas

  • Requires a working knowledge of Semgrep rules and syntax.
  • The quality of generated variants depends on the clarity and specificity of the initial rule.