Miro Security Basics Skill

Miro Security Basics

Overview

Security best practices for Miro OAuth 2.0 tokens, webhook signatures, and access control across the REST API v2.

Prerequisites

Miro app created at https://developers.miro.com
Understanding of OAuth 2.0 concepts
Secret management solution for production

OAuth Token Security

Never Store Tokens in Code

# .env (NEVER commit to git)
MIRO_CLIENT_ID=3458764500000001
MIRO_CLIENT_SECRET=your_client_secret_here
MIRO_ACCESS_TOKEN=eyJ...
MIRO_REFRESH_TOKEN=eyJ...

# .gitignore — MUST include these
.env
.env.local
.env.*.local
*.pem

Scope Minimization

Request only the scopes your app actually needs. Fewer scopes = smaller blast radius if a token is compromised.

| Use Case | Minimum Scopes | |----------|---------------| | Read-only dashboard | boards:read | | Board automation | boards:read, boards:write | | Team management | boards:read, team:read, team:write | | Enterprise admin | boards:read, organizations:read, auditlogs:read | | Full integration | boards:read, boards:write, identity:read |

Token Lifecycle Management

// src/miro/token-manager.ts

interface TokenInfo {
  accessToken: string;
  refreshToken: string;
  expiresAt: number;  // Unix timestamp in ms
  scopes: string[];
}

class MiroTokenManager {
  constructor(
    private storage: TokenStorage,   // DB, Redis, or Vault
    private clientId: string,
    private clientSecret: string,
  ) {}

  async getValidToken(userId: string): Promise<string> {
    const info = await this.storage.get(userId);
    if (!info) throw new Error('User not authorized');

    // Refresh 5 minutes before expiry
    if (Date.now() > info.expiresAt - 300_000) {
      return this.refreshToken(userId, info.refreshToken);
    }

    return info.accessToken;
  }

  private async refreshToken(userId: string, refreshToken: string): Promise<string> {
    const response = await fetch('https://api.miro.com/v1/oauth/token', {
      method: 'POST',
      headers: { 'Content-Type': 'application/x-www-form-urlencoded' },
      body: new URLSearchParams({
        grant_type: 'refresh_token',
        client_id: this.clientId,
        client_secret: this.clientSecret,
        refresh_token: refreshToken,
      }),
    });

    if (!response.ok) {
      // Refresh token revoked or expired — user must re-authorize
      await this.storage.delete(userId);
      throw new Error('Miro refresh token invalid. User must re-authorize.');
    }

    const data = await response.json();
    await this.storage.set(userId, {
      accessToken: data.access_token,
      refreshToken: data.refresh_token,
      expiresAt: Date.now() + data.expires_in * 1000,
      scopes: data.scope.split(' '),
    });

    return data.access_token;
  }
}

Webhook Signature Validation

Miro signs webhook payloads so you can verify they originate from Miro's servers.

import crypto from 'crypto';

function verifyMiroWebhookSignature(
  rawBody: Buffer | string,
  signature: string,
  secret: string,
): boolean {
  const expected = crypto
    .createHmac('sha256', secret)
    .update(rawBody)
    .digest('hex');

  // Timing-safe comparison to prevent timing attacks
  try {
    return crypto.timingSafeEqual(
      Buffer.from(signature, 'hex'),
      Buffer.from(expected, 'hex'),
    );
  } catch {
    return false; // Different lengths = not equal
  }
}

// Express middleware
app.post('/webhooks/miro',
  express.raw({ type: 'application/json' }),
  (req, res) => {
    const signature = req.headers['x-miro-signature'] as string;
    if (!signature || !verifyMiroWebhookSignature(req.body, signature, process.env.MIRO_WEBHOOK_SECRET!)) {
      return res.status(401).json({ error: 'Invalid signature' });
    }

    const event = JSON.parse(req.body.toString());
    // Process verified event...
    res.status(200).json({ received: true });
  }
);

Client Secret Rotation

# Step 1: Generate new secret in Miro app settings
# https://developers.miro.com > Your apps > Select app > App Credentials

# Step 2: Update secret in your environment
# For production (example with GCP Secret Manager):
gcloud secrets versions add miro-client-secret \
  --data-file=<(echo -n "new_secret_value")

# Step 3: Verify new secret works
curl -X POST https://api.miro.com/v1/oauth/token \
  -d "grant_type=refresh_token" \
  -d "client_id=$MIRO_CLIENT_ID" \
  -d "client_secret=NEW_SECRET" \
  -d "refresh_token=$MIRO_REFRESH_TOKEN"

# Step 4: Revoke old secret in Miro app settings

Request Signing for Audit Trails

interface MiroAuditEntry {
  timestamp: string;
  userId: string;
  endpoint: string;
  method: string;
  boardId?: string;
  requestId?: string;  // From X-Request-Id response header
  status: number;
}

async function auditedMiroFetch(
  userId: string,
  path: string,
  options: RequestInit = {},
): Promise<Response> {
  const response = await fetch(`https://api.miro.com${path}`, {
    ...options,
    headers: {
      'Authorization': `Bearer ${await tokenManager.getValidToken(userId)}`,
      'Content-Type': 'application/json',
      ...options.headers,
    },
  });

  const audit: MiroAuditEntry = {
    timestamp: new Date().toISOString(),
    userId,
    endpoint: path,
    method: options.method ?? 'GET',
    boardId: path.match(/boards\/([^/]+)/)?.[1],
    requestId: response.headers.get('X-Request-Id') ?? undefined,
    status: response.status,
  };

  // Log audit trail (never log token or request body)
  console.log('[MIRO_AUDIT]', JSON.stringify(audit));

  return response;
}

Security Checklist

[ ] Access tokens stored in environment variables or secret manager, never in code
[ ] .env files in .gitignore
[ ] OAuth scopes minimized per environment
[ ] Webhook signatures validated with timing-safe comparison
[ ] Token refresh handled before expiry (5-minute buffer)
[ ] Failed refresh triggers re-authorization flow
[ ] Client secret rotation procedure documented and tested
[ ] Audit logging captures endpoint, method, user, and status (never tokens)
[ ] X-Request-Id captured for support ticket correlation

Error Handling

| Security Issue | Detection | Mitigation | |----------------|-----------|------------| | Token in logs | Log audit | Redact Authorization headers in logging middleware | | Token in git | Pre-commit hook / secret scanning | Rotate immediately, revoke old token | | Webhook forgery | Signature validation fails | Return 401, alert security team | | Excessive scopes | Scope audit | Reduce to minimum needed per endpoint |

Resources

Next Steps

For production deployment, see miro-prod-checklist.

Agent Skills: Miro Security Basics

Install this agent skill to your local

Skill Files