These are the top 10 tips to improve Magento 2 Security:
1. Magento Security Scan Tool
Configure Magento Security Scan Tool.
2. Unique Admin Panel Route
Never use "/admin/" or any other common path as a route (front name) to your Magento 2 admin panel. This increases your chances of becoming a brute force victim. You can easily change the admin route (backend frontend name) following this link.
3. Enable ReCaptcha
Save your store from bots. In order to enable ReCaptcha in Magento 2.0.x - 2.2.x you need to install MSP ReCaptcha module (Magento 2.3 and greater already has it). ReCaptcha configurations can be found in Magento 2 Admin Panel > Stores > Configuration > Security > Google ReCaptcha. We recommend to use ReCaptcha for both Storefront and Admin Panel.
4. Disable Admin Account Sharing
Make sure the Admin Account Sharing option is disabled. In order to do that navigate to Stores > Configuration > Advanced > Admin and find the Security section. Once disabled, the login and password are used by only one admin so that every time someone else tries to log in another will be unlogged. That allows notifying any unauthorized admin account entries. Best of all is for each admin to have their own account.
5. Enable the Add Secret Key to URLs and Login is Case Sensitive.
6. Forced Password Change
Enforce the Password Change together with the Password Lifetime where you set the number of days you want your password to be changed in.
7. Access Control List
Use SSL (https://) on your website. Ask your server administrator or hosting provider to configure this and change the URLs by going to Stores > Configuration > Web.
9. Admin Activity Module
Install the Magento 2 Admin Activity Module. It allows you to track login activity including time, IP address and admin user name as well as all the performed changes in the admin panel.