WordPress secrets and credentials audit

A focused review for the secrets layer — what's stored, how it's generated, how it's compared, how it leaks. Narrow scope by design; run alongside wp-security-audit and wp-security-deep.

When to use this skill

Trigger when:

• Reviewing auth, registration, password reset, or 2FA flows.
• The plugin integrates a third-party API (Stripe, SendGrid, OpenAI, GitHub etc.) — look for stored credentials.
• The user asks "is my API key safe", "how should I store this token".
• Before wp.org submission (hardcoded secrets are a guaranteed reject).
• The diff contains: rand, mt_rand, uniqid, md5, sha1, password_hash, password_verify, setcookie, wp_generate_password, random_bytes, random_int, openssl_random_pseudo_bytes, update_option.*api_key, update_option.*secret, define.*KEY, define.*SECRET.

Audit checks

1. Hardcoded credentials in source

// HIGH — anyone with repo read access has prod credentials
const STRIPE_SECRET = 'sk_live_4eC39HqLyjWDarjtT1...';
$api_key = 'AIzaSy...';
define( 'MYPLUGIN_API_TOKEN', 'ghp_xxx...' );

Fix: load from wp-config.php constants (server-deployed, not in repo), an option (get_option) with admin-only write, or an env var via getenv(). Provide a settings page for the user to enter their own.

Search patterns:

• String literals matching common key prefixes: sk_, pk_live_, AKIA, ghp_, xoxb-, AIza, Bearer , eyJ (JWT), hex strings 32+ chars.
• define( '...KEY...', define( '...SECRET...', define( '...TOKEN...' with a non-empty literal.
• Long base64 strings in source ([A-Za-z0-9+/]{40,}={0,2}).

Flag any hit. Even "test" keys count — they get committed to prod.

2. Weak randomness for security tokens

// HIGH — predictable
$token = md5( uniqid() );
$reset_key = mt_rand();
$session_id = uniqid( '', true );

rand, mt_rand, uniqid are NOT cryptographically secure. They're seeded predictably and the output can be reconstructed.

Fix — use one of:

// WP-native, seeded from random_bytes internally
$token = wp_generate_password( 32, false ); // alnum
$token = wp_generate_password( 64, true, true ); // alnum + special

// PHP-native
$token = bin2hex( random_bytes( 32 ) ); // 64 hex chars
$num   = random_int( 100000, 999999 ); // 6-digit OTP

// WP nonce (for CSRF only — not a long-lived token!)
$nonce = wp_create_nonce( 'action' );

Don't confuse:

• wp_create_nonce is a 10-char CSRF token, valid 12-24h. NOT for password resets, API keys, session IDs.
• wp_generate_uuid4() is NOT cryptographically random despite the v4 UUID name. WordPress core implements it with mt_rand() (verified in wp-includes/functions.php). Use it for non-security identifiers (post UIDs, log IDs) only. For security tokens use wp_generate_password(), random_bytes(), or random_int().

3. Password storage

// HIGH — broken
$hash = md5( $password );
$hash = sha1( $password . SALT );
$hash = crypt( $password ); // weak default algo

WordPress provides wp_hash_password() / wp_check_password() — use these for WP user accounts. Since WP 6.8 the default algorithm is bcrypt (was PHPass / portable hash before). To work around bcrypt's 72-byte input limit, WP first HMAC-SHA384 pre-hashes the password, base64-encodes the result, then runs password_hash() with PASSWORD_BCRYPT, prefixing the output with $wp to distinguish it from vanilla bcrypt. wp_check_password() still verifies legacy PHPass hashes from older sites and rehashes on successful login, so the migration is transparent — don't reimplement password storage for WP users, always go through these functions.

The algorithm and options are filterable (wp_hash_password_algorithm, wp_hash_password_options) for sites that want argon2id or stronger bcrypt cost — but a plugin should not change site-wide defaults unless explicitly asked.

For non-WP-user passwords (custom auth, API client secrets):

$hash = password_hash( $password, PASSWORD_DEFAULT );
// later
if ( password_verify( $input, $hash ) ) { /* ok */ }
if ( password_needs_rehash( $hash, PASSWORD_DEFAULT ) ) {
    // rehash and update store
}

PASSWORD_DEFAULT resolves to bcrypt across all currently shipped PHP versions and may change in a future major PHP release — that's the point of the constant. Always pair it with password_needs_rehash() on verification to migrate stored hashes when the algorithm changes. Allocate at least 255 bytes for the stored hash column to leave room for future algorithm output growth. Never roll your own with hash()

• salt.

4. Cookie flags

// MEDIUM/HIGH — readable by JS, sent over HTTP, sent cross-site
setcookie( 'session', $token, time() + 3600 );

Fix:

setcookie( 'myplugin_session', $token, [
    'expires'  => time() + 3600,
    'path'     => COOKIEPATH ?: '/',
    'domain'   => COOKIE_DOMAIN ?: '',
    'secure'   => is_ssl(),
    'httponly' => true,
    'samesite' => 'Lax', // or 'Strict' for sensitive flows
] );

For WP's own auth, don't roll your own — use wp_set_auth_cookie which handles all flags correctly.

Flag: any setcookie storing a token, session ID, or user identifier without secure (when is_ssl()) and httponly.

5. Secrets in logs and debug output

// MEDIUM — secrets in error_log, often shipped to log aggregators
error_log( 'API request: ' . print_r( $request, true ) ); // includes auth header
var_dump( $_SERVER ); // HTTP_AUTHORIZATION leaks
WP_CLI::log( "Token: $token" );

Flag:

• error_log, var_dump, print_r, var_export over variables named *token*, *key*, *secret*, *password*, *auth*, $_SERVER, full request bodies, or response objects with auth headers.
• WP_DEBUG_LOG enabled in production code path (not a check, but warn if define( 'WP_DEBUG_LOG', true ) appears in plugin code — shouldn't be set by a plugin).

Fix: redact before logging:

$safe = $request;
unset( $safe['headers']['Authorization'] );
$safe['body'] = '<redacted>';
error_log( wp_json_encode( $safe ) );

6. Storing API keys: option vs constant

Both are common — guidance:

• Constant in wp-config.php: best for site-owner-managed, rarely-changed secrets. Not in DB, not in repo, only readable by PHP. Document this in plugin readme.
• Option (update_option): needed when the plugin offers a settings page. Acceptable, but:
  • Mark the option autoload = false if not needed every request.
  • Restrict the setting page to manage_options.
  • Don't wp_send_json or echo the option value back to non-admins.
• User meta: only for per-user tokens (e.g. user's own GitHub PAT). Never for site-wide secrets.

Flag: site-wide secrets stored in user meta, or settings pages without a capability check.

7. Token comparison

Cross-reference with wp-security-deep check #8: any secret comparison must use hash_equals( $stored, (string) $given ). Never == or ===.

Severity guide

• HIGH: hardcoded secret in source, weak randomness for password reset / session token, password stored with md5/sha1, missing HttpOnly on session cookie.
• MEDIUM: secrets logged, cookie missing SameSite, weak randomness for non-secret IDs that gain meaning later.
• LOW: API key in option without autoload = false, no rotation story documented.

Report format

Same as wp-security-audit. If hardcoded secrets are found, the report MUST include a top-line warning recommending:

1. Revoke the leaked credential at the issuing service immediately.
2. Rotate to a new secret.
3. Rewrite git history to remove the secret (git filter-repo or BFG) — or accept that the secret is permanently compromised in the repo.
4. Move to wp-config.php constant or settings option.

State this even when the user only asked for a code review — leaked secrets need real-world action, not just a code change.

Cross-references

• wp-security-audit: basic sanitize/escape/nonce/capability.
• wp-security-deep: object injection, SSRF, CSRF on GET, mass assignment, file include, mail/zip injection, type juggling, race.

What this skill does NOT cover

• Cryptographic protocol design (key derivation, signing schemes, envelope encryption).
• Secret scanning of git history (use gitleaks, trufflehog).
• Secret rotation processes / KMS integrations.
• Hardware token / 2FA flow correctness beyond storage.

References

• PHP password hashing: https://www.php.net/manual/en/function.password-hash.php
• random_bytes: https://www.php.net/manual/en/function.random-bytes.php
• wp_generate_password: https://developer.wordpress.org/reference/functions/wp_generate_password/
• OWASP secret management: https://cheatsheetseries.owasp.org/cheatsheets/Secrets_Management_Cheat_Sheet.html