no-password-in-url

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Prevents passwords in URL query parameters or fragments

This rule detects when URLs contain password-related query parameters or URL fragments

Severity: 🔴 CRITICAL
CWE: CWE-521: Weak Password Requirements
OWASP Mobile: M1: Improper Credential Usage

Rule Details

This rule detects when URLs contain password-related query parameters or URL fragments. Passwords in URLs are logged in browser history, server logs, proxy logs, and referrer headers, creating permanent credential leaks.

Why This Matters

URLs with passwords are fundamentally insecure:

Browser history: Passwords saved in autocomplete and history
Server logs: All web servers log full URLs including query params
Referrer headers: Passwords leaked to third-party sites via Referer header
Proxy logs: Corporate/ISP proxies log all URLs
Compliance: Violates PCI-DSS, HIPAA, and security best practices

❌ Incorrect

// Password in query parameter
window.location.href = 'https://example.com/login?password=secret123'; // ❌ Logged everywhere

// Password in URLSearchParams
const params = new URLSearchParams({
  username: 'user',
  password: userPassword, // ❌ Will appear in URL
});
fetch(`https://api.example.com/auth?${params}`);

// Password in hash fragment
window.location.hash = `#password=${pwd}`; // ❌ Visible in browser history

// Mailto with password
window.open(`mailto:support@example.com?subject=Reset&body=password:${pwd}`); // ❌ Email leak

✅ Correct

// POST passwords in request body (never URL)
fetch('https://api.example.com/login', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    username: 'user',
    password: userPassword, // ✅ In POST body, not URL
  }),
});

// Use Authorization header for credentials
fetch('https://api.example.com/data', {
  headers: {
    Authorization: `Basic ${btoa(`${username}:${password}`)}`, // ✅ Header, not URL
  },
});

// OAuth flow with authorization code (no password in URL)
const authUrl = new URL('https://oauth.example.com/authorize');
authUrl.searchParams.set('client_id', clientId);
authUrl.searchParams.set('redirect_uri', redirectUri);
authUrl.searchParams.set('response_type', 'code'); // ✅ No password, just auth code
window.location.href = authUrl.toString();

// Never pass credentials in URLs - use secure cookies/tokens
document.cookie = `session=${sessionToken}; Secure; HttpOnly; SameSite=Strict`; // ✅ Cookie, not URL

⚙️ Configuration

This rule has no configuration options.

Known False Negatives

Passwords in Dynamically Constructed URLs

Why: We only detect literal URL strings with password params. Dynamic URL construction is not traced.

// ❌ NOT DETECTED - Dynamic construction
const baseUrl = 'https://example.com/auth';
const fullUrl = `${baseUrl}?password=${pwd}`; // Dynamic template
window.location.href = fullUrl;

Mitigation: Never construct URLs with password parameters. Always use POST body or headers.

Password in URL Objects

Why: We detect string literals, not URL object manipulation.

// ❌ NOT DETECTED - URL object
const url = new URL('https://example.com/login');
url.searchParams.set('password', pwd); // Object method, not literal
fetch(url.toString());

Mitigation: Code review for all URL parameter assignments. Ban password in query params.

Third-Party Library URL Building

Why: Libraries that internally construct URLs are not analyzed.

// ❌ NOT DETECTED - Library handles URL
await httpClient.get('/auth', { params: { password: pwd } }); // axios/similar

Mitigation: Configure HTTP libraries to never allow credentials in URLs. Review library docs.

[no-hardcoded-credentials](./no-hardcoded-credentials. md) - Detect hardcoded passwords
no-credentials-in-query-params - General credential leak prevention