Flo
382a35c47e
Address critical and high findings from an external security review. Critical/high fixes: - reset-signing no longer treats general-purpose keys (id_ed25519, etc.) as deletion candidates, defaults the delete prompt to No, and never deletes files in -y mode - FIDO2 retry now re-runs the same attempt (for-loop reassignment bug silently advanced to the next fallback key type) - core.hooksPath redirection installs dispatch stubs for all client-side hook types so repo-local hooks (husky, lefthook, pre-commit) keep running; pre-commit combines gitleaks with dispatch and warns loudly when gitleaks is absent - public-key validation everywhere a key path is consumed, preventing private key material in allowed_signers or user.signingkey - config backups written mode 600 (may contain tokens) - SSH config audit/apply is scope-aware (global vs host-specific), appends new directives at EOF to preserve precedence, scans Include-d files for keys - pubkey algorithm restriction guarded against RSA/DSA-only lockout and chooses the directive name by OpenSSH version Added: - audit tiers (security/hygiene/preference); --audit exit 2 reflects security-tier issues only - signing smoke test catching No-principal-matched at setup time - http.sslVerify audit distinguishes unset from insecure override Docs: correct fsmonitor precedence, log.showSignature and fsckObjects breakage, SSH scoping semantics in REASONING.md; plan for agent-backed keys (1Password/Bitwarden/forwarded agents) in docs/specs. 126/126 BATS tests pass; shellcheck clean. Closes #53 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
git-harden.sh
Audit and harden your global git configuration with security-focused defaults.
Protects against history rewriting, supply chain attacks, credential theft, and malicious repository exploitation. Runs on macOS and Linux.
Quick Start
# Clone and run
git clone https://github.com/YOUR_ORG/git-hardening.git
cd git-hardening
chmod +x git-harden.sh
# Audit your current config (no changes)
./git-harden.sh --audit
# Interactive mode — review and approve each change
./git-harden.sh
# Apply all recommended defaults without prompting
./git-harden.sh -y
On first interactive run, the script asks you to confirm you've reviewed it for safety. If you haven't, it prints instructions for piping it to Claude Code or Gemini CLI for an automated review.
What It Does
The script runs in two phases:
- Audit — scans your current
git config --globaland~/.ssh/config, prints a color-coded report:[OK]already set to the recommended value[WARN]set to a non-recommended value[MISS]not configured
- Apply — for each non-OK setting, shows what it does and prompts you to accept or skip (or auto-applies with
-y)
Settings Applied
| Category | What it does |
|---|---|
| Identity | user.useConfigOnly=true — prevents commits without explicit identity |
| Object integrity | fsckObjects on transfer/fetch/receive, transfer.bundleURI=false, fetch.prune=true |
| Protocol restrictions | Default-deny policy: only HTTPS and SSH. Blocks git:// and ext://. Forces protocol.version=2 |
| Filesystem protection | core.protectNTFS, core.protectHFS, core.fsmonitor=false, core.symlinks=false (interactive-only) |
| Hook control | Redirects core.hooksPath to ~/.config/git/hooks so repo-local hooks can't execute |
| Pre-commit hook | Installs gitleaks secret scanner as global pre-commit hook (with SKIP_GITLEAKS bypass) |
| Repository safety | safe.bareRepository=explicit, submodule.recurse=false, detects/removes safe.directory=* wildcard |
| Pull/merge hardening | pull.ff=only, merge.ff=only — refuses non-fast-forward merges |
| Transport security | Rewrites http:// to https://, enforces http.sslVerify=true |
| Credential storage | Platform-detected secure helper (osxkeychain on macOS, libsecret on Linux). Warns if using plaintext store |
| Credential hygiene | Warns about plaintext ~/.git-credentials, ~/.netrc, ~/.npmrc (tokens), ~/.pypirc (passwords) |
| Global gitignore | Creates ~/.config/git/ignore with patterns for secrets, credentials, and OS/IDE artifacts |
| Defaults | init.defaultBranch=main |
| Forensic readiness | Extended reflog retention (gc.reflogExpire=180.days, gc.reflogExpireUnreachable=90.days) |
| Commit signing | SSH-based signing with interactive key setup wizard (software or FIDO2 hardware key) |
| SSH hardening | StrictHostKeyChecking=accept-new, HashKnownHosts=yes, IdentitiesOnly=yes, modern algorithm restrictions |
| SSH key hygiene | Audits ~/.ssh/*.pub for weak key types (DSA, ECDSA, short RSA) |
| Visibility | log.showSignature=true |
A config backup is saved to ~/.config/git/pre-harden-backup-<timestamp>.txt before any changes.
Signing Setup
The script includes an interactive wizard that:
- Detects existing SSH keys (including custom-named keys from
~/.ssh/config) - Detects FIDO2 hardware (YubiKey, etc.)
- Offers two tiers:
- Software SSH key — use existing
ed25519or generate one - FIDO2 hardware key — generate
ed25519-skwith touch-to-sign (if hardware detected)
- Software SSH key — use existing
- Configures
user.signingkey,commit.gpgsign,tag.gpgsign - Sets up
~/.config/git/allowed_signersfor local signature verification
With -y, the script auto-detects the best available key. If no key exists, signing config is prepared but not enabled (to avoid breaking commits).
Privacy note: The signing wizard warns that reusing the same signing key across personal and work accounts enables cross-platform identity correlation (OSINT risk). For identity separation, generate dedicated keys per context and use git's includeIf for per-org config.
Usage
git-harden.sh [OPTIONS]
Options:
--audit Audit only, no changes (exit code 2 if issues found)
-y, --yes Auto-apply all recommended defaults
--help, -h Show help
--version Show version
Exit Codes
| Code | Meaning |
|---|---|
| 0 | All OK, or changes applied successfully |
| 1 | Error (missing dependencies, etc.) |
| 2 | Audit found issues (--audit mode) |
Requirements
git>= 2.34.0 (required for SSH signing)ssh-keygen- Bash 3.2+ (compatible with macOS default bash)
Optional:
gitleaksfor pre-commit secret scanning (hook is installed regardless; scans run only if gitleaks is on$PATH)ykmanorfido2-tokenfor FIDO2 hardware key detection
Threat Model
What this protects against
- History rewriting —
pull.ff=onlyandmerge.ff=onlyrefuse non-fast-forward operations, making force-pushed changes visible - Object injection —
fsckObjectsvalidates every object transferred, catching corruption or malicious payloads - Protocol downgrade — blocks plaintext
git://and dangerousext://protocol - Hook-based RCE — redirects hook execution away from repo-local
.git/hooks/ - Submodule attacks — disables auto-recursion; submodules must be explicitly initialized
- Credential theft — ensures secure credential storage, warns about plaintext
store, detects leaked credentials in~/.git-credentials,~/.netrc,~/.npmrc,~/.pypirc - Secret leakage — gitleaks pre-commit hook blocks commits containing secrets before they enter git history
- Commit impersonation — SSH signing proves key possession (anyone can fake
user.name/user.email) - Filesystem tricks — blocks NTFS/HFS+/symlink path manipulation attacks
- Weak SSH keys — audits and warns about DSA, ECDSA, and short RSA keys
What this does NOT protect against
- A compromised machine (malware can use cached keys)
- Malicious code from an authorized signer
- Historical unsigned commits (signing is not retroactive)
- Server-side misconfigurations (see admin recommendations printed by the script)
Admin Recommendations
The script prints (but does not apply) server/org-level recommendations:
- Enable "require signed commits" on protected branches
- Enable GitHub/GitLab vigilant mode
- Restrict force-pushes server-side
- Use fine-grained, short-lived tokens in CI/CD
- Maintain an allowed signers file in repos
- Clone untrusted repos with
--no-recurse-submodules - Use separate signing keys per org to prevent cross-platform identity correlation (OSINT)
Signing with FIDO2 hardware keys
The script includes an interactive wizard that:
- Detects existing SSH keys (including custom-named keys from
~/.ssh/config) - Detects FIDO2 hardware (YubiKey, etc.)
- Offers two tiers:
- Software SSH key — use existing
ed25519or generate one - FIDO2 hardware key — generate
ed25519-skwith touch-to-sign (if hardware detected)
- Software SSH key — use existing
- Configures
user.signingkey,commit.gpgsign,tag.gpgsign - Sets up
~/.config/git/allowed_signersfor local signature verification
These combinations of hardware and OS have been tested:
Running Tests
# Init test framework submodules (first time only)
git submodule update --init --recursive
# Unit tests (BATS) — runs in isolated $HOME, never touches real config
./test/run.sh
# Interactive tests (tmux) — tests the full interactive flow on macOS/Linux
./test/run-interactive.sh
# Full e2e matrix — containers + interactive tests across distros
# Requires docker or podman
./test/e2e.sh # All distros + host
./test/e2e.sh --skip-host ubuntu # Single distro, skip host
./test/e2e.sh --runtime podman --skip-host # All distros via podman
./test/e2e.sh --rebuild alpine # Force image rebuild
| Test tier | What it covers | Requirements |
|---|---|---|
test/run.sh |
92 BATS unit tests — config audit, apply, signing, key detection | bats-core submodule |
test/run-interactive.sh |
4 tmux-driven tests — full accept, safety gate, signing wizard | tmux |
test/e2e.sh |
Container matrix (Ubuntu, Debian, Fedora, Alpine, Arch) + host interactive | docker or podman |
All tests run in isolated environments and never modify your real git or SSH configuration.
License
MIT