# Security Guide A hook configuration is executable project code. Installing a Git shim or running `prek run` authorizes the selected hooks, their installation steps, and their dependencies to execute with the current user's permissions. ## Review configurations before running them Treat an unfamiliar `prek.toml` or `.pre-commit-config.yaml` like an unfamiliar build script: - Review remote repository URLs, revisions, hook entries, and additional dependencies. - Review local hooks and checked-in scripts, especially entries that explicitly invoke a shell. - Inspect configuration changes in pull requests before running them locally. - Use tighter credentials and isolation for untrusted repositories. This is especially important for a global Git hook that discovers and runs each repository's config automatically. Such a hook can execute project-controlled code during an ordinary Git operation. ## Pin remote hooks A full commit SHA is the strongest Git pin because it names immutable content. A version tag is easier to read and is commonly used for releases, but Git tags can be moved by a repository maintainer. Branch names are mutable and should not be treated as repeatable pins. Use `prek update --freeze` to write commit SHAs when immutable pins are required. Review the resulting revision changes before committing them. ## Downloads and checksums For managed download paths that support checksum sidecars, prek verifies the download when the upstream source provides that metadata. The [download checksum policy]() controls what happens when metadata is missing; it cannot create authenticity information that an upstream source did not publish. Release artifacts for prek itself include GitHub attestations. See [Artifact Verification](). ## Credentials and logs Use a credential helper or short-lived CI token for private hook repositories. Avoid embedding credentials in repository URLs or configuration files. Verbose hook output and `prek.log` can contain repository paths, command arguments, and tool output, so review and redact logs before sharing them publicly.