Detecting Secrets

Secret Patterns

Look for these categories of hardcoded secrets in code:

High-Confidence Patterns

Lower-Confidence Patterns (Require Context)

• Base64-encoded strings in configuration (may be encrypted or may be cleartext secrets)
• JWT tokens (may be test tokens or production tokens)
• Hex strings of 32+ characters (may be encryption keys or hashes)
• URLs with embedded credentials (https://user:pass@host)

Context-Aware Detection

Distinguish real secrets from false positives. Not every pattern match indicates an actual secret — consider context:

Test Fixtures and Mock Data

csharpCopy code
// NOT a real secret — test fixture with obvious fake value
var testApiKey = "test-api-key-not-real-12345";
var mockPassword = "P@ssword123"; // Used only in unit tests

// REAL secret — production-looking value in non-test code
var apiKey = "sk-proj-abc123def456ghi789jkl012mno345pqr678stu901vwx";

Decision criteria:

• Is it in a test directory (**/test/**, **/tests/**, **/*.Test/**)?
• Does the value contain obvious placeholder text ("test", "fake", "mock", "example", "placeholder")?
• Is the value used in assertions or mock setups?

Example and Placeholder Values

jsonCopy code
// NOT a real secret — documented example
{
  "apiKey": "YOUR_API_KEY_HERE"
}

// REAL secret — actual value in config
{
  "apiKey": "sk-proj-abc123def456ghi789jkl012mno345pqr678stu901vwx"
}

Encrypted or Hashed Values

• Hashed passwords (bcrypt $2b$, argon2 $argon2id$) are NOT secrets — they're properly stored
• Encrypted values with proper key management are NOT secrets in the same way
• But the encryption KEY itself, if hardcoded, IS a secret

Common Hiding Spots

Search these locations when auditing for secrets:

GitHub Secret Scanning Integration

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# List all secret scanning alerts
gh api /repos/{owner}/{repo}/secret-scanning/alerts --jq '.[] | {number, state, secret_type, secret_type_display_name, created_at, push_protection_bypassed}'

# Get details for a specific alert
gh api /repos/{owner}/{repo}/secret-scanning/alerts/{alert_number}

# List alerts that bypassed push protection
gh api "/repos/{owner}/{repo}/secret-scanning/alerts?state=open" --jq '.[] | select(.push_protection_bypassed == true)'

Push protection prevents commits containing detected secrets from being pushed. When someone bypasses push protection, the alert is flagged — review these with extra scrutiny.

Remediation Workflow

When a secret is found in code, follow this sequence:

1. Rotate Immediately

Assume any committed secret is compromised. Even if the repo is private, the secret may have been cached, logged, or accessed by CI/CD systems.

• Revoke the existing credential
• Generate a new credential
• Update the credential wherever it's used (services, deployments)

2. Remove from Code

Replace the hardcoded secret with a secure reference:

csharpCopy code
// WRONG — hardcoded secret
var connectionString = "Server=prod.db;Password=s3cr3t!";

// CORRECT — environment variable
var connectionString = Environment.GetEnvironmentVariable("DB_CONNECTION_STRING");

// CORRECT — Azure Key Vault (Bitwarden's approach)
var connectionString = await keyVaultClient.GetSecretAsync("db-connection-string");

3. Remove from Git History (If Needed)

If the secret was committed to a public repo or a repo that will become public:

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# Using git filter-repo (preferred over filter-branch)
git filter-repo --path-glob '*.json' --replace-text expressions.txt

# expressions.txt format:
# literal:the-secret-value==>REDACTED

Warning: Rewriting git history is destructive and affects all collaborators. Only do this when the secret was exposed in a public or soon-to-be-public repository.

4. Prevent Recurrence

• Add patterns to .gitignore for files that should never be committed (.env, *.pfx, appsettings.Development.json)
• Enable GitHub push protection for the repository
• Use secret scanning custom patterns for organization-specific secret formats

Secure Alternatives

Bitwarden uses Azure Key Vault for secrets management, provisioned by the BRE team:

For local development, use user-secrets or .env files that are .gitignored — never commit them.

Critical Rules

• Assume any committed secret is compromised. Always rotate, even if the repo is private. No exceptions.
• Never suppress secret scanning alerts without rotation. Dismissing an alert doesn't make the exposure go away.
• Validation, not just detection. When a potential secret is found, verify it's real before raising an alarm. Check if it's a test value, placeholder, or encrypted content.
• Check the full commit history. A secret removed in the latest commit may still exist in git history. Use git log -p -S "secret-pattern" to search history.
• Bitwarden uses Azure Key Vault for secrets management. If a new secret needs to be stored, work with BRE to provision vault access for the repository.