secret-blocking

name	secret-blocking
description	Detects and blocks hardcoded secrets — API keys, tokens, private keys, and database connection strings — before they are written to disk, committed to git, or echoed to logs. Covers 40+ patterns across Stripe, AWS, GitHub, GitLab, OpenAI, Anthropic, Slack, Google, SendGrid, Mailgun, Square, Twilio, and generic credential formats. Apply on every file write, every diff review, and every shell command that emits configuration.
license	MIT
metadata	{"catpilot":{"id":"secret-blocking","version":"1.0.0","severity":"critical","category":"secrets","applies_to":{"languages":["any"],"frameworks":["any"],"runtimes":["claude-code","cursor","openclaw","cline","aider","copilot","codex-cli"]},"control_mappings":{"soc2":["CC6.1","CC6.6","CC7.2"],"pci_dss":["3.4","3.5","3.6","8.2.1"],"iso_27001":["A.9.4.3","A.10.1.1","A.10.1.2"],"nist_csf":["PR.AC-1","PR.DS-1","PR.DS-5"],"owasp_top_10":["A02:2021","A07:2021"]},"provenance":{"origin":"catpilot","incident_derived":false},"maintainers":[{"team":"catpilot-security"}],"references":["https://owasp.org/www-project-top-ten/A02_2021-Cryptographic_Failures/","https://docs.github.com/en/code-security/secret-scanning/about-secret-scanning","https://cheatsheetseries.owasp.org/cheatsheets/Secrets_Management_Cheat_Sheet.html"]}}

When to apply

Apply on every code generation, file write, file edit, and diff review. Apply also on shell commands the agent is about to execute that include inline credentials, environment variable assignments, or curl -H headers.

This skill is one of the always-on critical skills. It is cheap to evaluate (regex over the diff or the proposed write), and the cost of a false negative is a leaked credential that ends up in git history forever.

Why

A hardcoded secret in a public repository has, on average, been scraped within minutes of the push. Rotation is required even if the commit is deleted — git history is forever, and bots monitor force-pushes too. Detection at the agent layer, before the file write, is the cheapest place to catch this.

Rules

• [critical] Never write a literal secret into source code, config files, comments, test fixtures, or documentation.
• [critical] Never echo a secret in a shell command the agent intends to run (e.g. curl -H "Authorization: Bearer sk-ant-..."). Use environment variables.
• [critical] Never paste a secret into a commit message, PR description, or issue body.
• [high] Never write .env files containing real secrets. Generate .env.example with placeholder values instead, and ensure .env is in .gitignore.
• [high] Never include a secret in a log statement, even at DEBUG level.
• [medium] Prefer secret managers (AWS Secrets Manager, Azure Key Vault, Google Secret Manager, HashiCorp Vault, Doppler, 1Password Secrets Automation) over .env for production deployments.
• [medium] When generating example code, use clearly fake placeholders (your-api-key-here, REPLACE_ME) rather than realistic-looking strings.

[!agent] When you detect a match for any pattern in the "Detection patterns" table below, stop. Do not write the file. Surface the match to the user, name the provider, and propose the environment-variable or secret-manager remediation. Do not proceed without explicit confirmation that the value is a known-fake test fixture.

Detection patterns

Pattern (regex, case-sensitive)	Provider / Type	Example
\bsk_live_[A-Za-z0-9]{20,}\b	Stripe live secret key	sk_live_51H...
\bsk_test_[A-Za-z0-9]{20,}\b	Stripe test secret key	sk_test_4eC39...
\bpk_live_[A-Za-z0-9]{20,}\b	Stripe live publishable	pk_live_51H...
\bpk_test_[A-Za-z0-9]{20,}\b	Stripe test publishable	pk_test_TYoo...
\brk_live_[A-Za-z0-9]{20,}\b	Stripe restricted key	rk_live_...
\bAKIA[0-9A-Z]{16}\b	AWS Access Key ID	AKIAIOSFODNN7EXAMPLE
\bASIA[0-9A-Z]{16}\b	AWS temp Access Key ID	ASIAIOSFODNN7EXAMPLE
aws_secret_access_key\s*=\s*["']?[A-Za-z0-9/+=]{40}["']?	AWS secret access key	40-char base64
\bghp_[A-Za-z0-9]{36}\b	GitHub personal token	ghp_xxxxxxxx...
\bgho_[A-Za-z0-9]{36}\b	GitHub OAuth token	gho_xxxxxxxx...
\bghu_[A-Za-z0-9]{36}\b	GitHub user-to-server	ghu_xxxxxxxx...
\bghs_[A-Za-z0-9]{36}\b	GitHub server-to-server	ghs_xxxxxxxx...
\bghr_[A-Za-z0-9]{36}\b	GitHub refresh token	ghr_xxxxxxxx...
\bglpat-[A-Za-z0-9_\-]{20,}\b	GitLab personal token	glpat-xxxx...
\bsk-ant-(?:api|admin)\d+-[A-Za-z0-9_\-]{80,}\b	Anthropic API key	sk-ant-api03-...
\bsk-(?:proj-)?[A-Za-z0-9_\-]{40,}\b	OpenAI API key	sk-proj-... (56+ chars)
\bxox[abprs]-[A-Za-z0-9-]{10,}\b	Slack token	xoxb-123-456-abc
\bAIza[0-9A-Za-z_\-]{35}\b	Google API key	AIzaSyD...
\bya29\.[A-Za-z0-9_\-]+\b	Google OAuth access token	ya29.a0AfH...
\bsq0[a-z]{3}-[A-Za-z0-9_\-]{20,}\b	Square token	sq0atp-..., sq0csp-...
\bSG\.[A-Za-z0-9_\-]{22}\.[A-Za-z0-9_\-]{43}\b	SendGrid API key	SG.xxx.yyy
\bkey-[a-f0-9]{32}\b	Mailgun API key	key-xxxx...
\bSK[a-f0-9]{32}\b	Twilio API SID	SKxxxx...
\bAC[a-f0-9]{32}\b	Twilio Account SID	ACxxxx...
\bDOCKER_AUTH_CONFIG\s*=\s*	Docker registry creds	env-style
npm_[A-Za-z0-9]{36}	npm access token	npm_xxxx...
\beyJ[A-Za-z0-9_\-]{20,}\.[A-Za-z0-9_\-]{20,}\.[A-Za-z0-9_\-]{20,}\b	JWT with payload	three-part eyJ...
`-----BEGIN (?:RSA	EC	DSA
-----BEGIN CERTIFICATE-----	TLS / x509 cert	Cert in source
mongodb(?:\+srv)?://[^:\s]+:[^@\s]+@	MongoDB URI w/ password	mongodb+srv://u:p@host
postgres(?:ql)?://[^:\s]+:[^@\s]+@	Postgres URI w/ password	postgres://u:p@host
mysql://[^:\s]+:[^@\s]+@	MySQL URI w/ password	mysql://u:p@host
redis://[^:\s]*:[^@\s]+@	Redis URI w/ password	redis://:pw@host
amqp(?:s)?://[^:\s]+:[^@\s]+@	RabbitMQ URI w/ password	amqps://u:p@host
(?i)\b(?:api[_-]?key|apikey)\s*[:=]\s*["'][A-Za-z0-9_\-]{16,}["']	Generic API key literal	api_key="..."
(?i)\b(?:password|passwd|pwd)\s*[:=]\s*["'][^"']{6,}["']	Hardcoded password	password="..."
(?i)\b(?:secret|client_secret)\s*[:=]\s*["'][A-Za-z0-9_\-]{16,}["']	OAuth client secret	client_secret="..."
(?i)\b(?:token|auth_token|access_token)\s*[:=]\s*["'][A-Za-z0-9_\-\.]{16,}["']	Auth tokens	token="..."
(?i)\bbearer\s+[A-Za-z0-9_\-\.=]{16,}\b	Bearer in headers	Authorization: Bearer ...
(?i)\baz(?:ure)?[_-]?(?:client[_-]?secret|tenant[_-]?id)\s*[:=]\s*	Azure credentials	inline assignments
(?i)\bDATABASE_URL\s*=\s*[^$\s][^"'\s]+	DB URL set to literal (not ${...})	DATABASE_URL=postgres://...

Patterns are intentionally conservative on length/charset to minimize false positives in test fixtures. When in doubt, ask the user.

Negative examples

# ❌ Stripe live key in source — leaks the moment this is pushed
import stripe
stripe.api_key = "sk_live_<REDACTED_FAKE_EXAMPLE_DO_NOT_SCAN>"

// ❌ OpenAI key in a Next.js client component — also ships to the browser
const client = new OpenAI({
  apiKey: "sk-proj-AbCdEf123456789..."
});

# ❌ AWS keys in a docker-compose.yml committed to the repo
services:
  api:
    environment:
      AWS_ACCESS_KEY_ID: AKIAIOSFODNN7EXAMPLE
      AWS_SECRET_ACCESS_KEY: wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY

# ❌ Connection string with embedded password
DATABASE_URL = "postgres://app:[e-mail]:5432/prod"

# ❌ Bearer token inlined into a curl invocation in a script
curl -H "Authorization: Bearer ghp_xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" \
  https://api.github.com/user

# ❌ Secret baked into an image layer — visible to anyone with `docker history`
ENV STRIPE_API_KEY=sk_live_<REDACTED_FAKE_EXAMPLE_DO_NOT_SCAN>

# ❌ Private key committed alongside test fixtures
PRIVATE_KEY = """-----BEGIN RSA PRIVATE KEY-----
MIIEowIBAAKCAQEA1...
-----END RSA PRIVATE KEY-----"""

Remediation

Pattern 1: read from environment

# ✅ Python
import os
import stripe
stripe.api_key = os.environ["STRIPE_API_KEY"]

// ✅ Node / TypeScript
const apiKey = process.env.STRIPE_API_KEY;
if (!apiKey) {
  throw new Error("STRIPE_API_KEY is not set");
}

// ✅ Go
apiKey := os.Getenv("STRIPE_API_KEY")
if apiKey == "" {
    log.Fatal("STRIPE_API_KEY is not set")
}

Pattern 2: .env for local dev, never committed

# .env  (must be in .gitignore — always check)
STRIPE_API_KEY=sk_live_...
DATABASE_URL=postgres://app:...@localhost:5432/dev

# .gitignore
.env
.env.*
!.env.example

# .env.example  (committed; placeholders only)
STRIPE_API_KEY=sk_live_REPLACE_ME
DATABASE_URL=postgres://app:REPLACE_ME@localhost:5432/dev

Pattern 3: secret manager in production

# ✅ AWS Secrets Manager
import boto3, json
sm = boto3.client("secretsmanager")
secret = json.loads(sm.get_secret_value(SecretId="prod/stripe")["SecretString"])
stripe.api_key = secret["api_key"]

// ✅ Azure Key Vault
import { DefaultAzureCredential } from "@azure/identity";
import { SecretClient } from "@azure/keyvault-secrets";

const credential = new DefaultAzureCredential();
const client = new SecretClient(process.env.KEY_VAULT_URL!, credential);
const secret = await client.getSecret("stripe-api-key");
stripe.apiKey = secret.value!;

Pattern 4: Docker build secrets (BuildKit)

# syntax=docker/dockerfile:1.4
FROM node:20@sha256:abc123...
# ✅ Mounted at build time, never persisted in any layer
RUN --mount=type=secret,id=npmrc,target=/root/.npmrc \
    npm install

docker build --secret id=npmrc,src=$HOME/.npmrc -t myapp .

Pattern 5: CI/CD — never echo, always mask

# ✅ GitHub Actions
- name: Deploy
  env:
    STRIPE_API_KEY: ${{ secrets.STRIPE_API_KEY }}
  run: ./deploy.sh   # script reads from env, does not echo

# ❌ Never:
# run: echo "Deploying with key ${{ secrets.STRIPE_API_KEY }}"

If a secret has already been committed

This is an incident. Run, in order:

1. Rotate the credential immediately at the provider. Assume it is already compromised.
2. Audit usage logs at the provider for unauthorized calls.
3. Purge git history with git filter-repo or BFG Repo-Cleaner. A new commit deleting the file does not remove the value from history.
4. Force-push the rewritten history (coordinate with the team — this rewrites everyone's clones).
5. Invalidate cached copies: GitHub forks, mirrors, CI caches, container registries that pulled the affected commit.

The full incident-response playbook is in the incident-response skill.

References

• OWASP A02:2021 — Cryptographic Failures: https://owasp.org/www-project-top-ten/A02_2021-Cryptographic_Failures/
• OWASP A07:2021 — Identification and Authentication Failures: https://owasp.org/www-project-top-ten/A07_2021-Identification_and_Authentication_Failures/
• OWASP Secrets Management Cheat Sheet: https://cheatsheetseries.owasp.org/cheatsheets/Secrets_Management_Cheat_Sheet.html
• GitHub Secret Scanning patterns: https://docs.github.com/en/code-security/secret-scanning/secret-scanning-patterns
• AWS Secrets Manager: https://docs.aws.amazon.com/secretsmanager/
• Azure Key Vault: https://learn.microsoft.com/en-us/azure/key-vault/
• Google Secret Manager: https://cloud.google.com/secret-manager/docs
• HashiCorp Vault: https://developer.hashicorp.com/vault/docs