Initial access to your network was purchased on the dark web. Then kerberoasting was carried out and we got passwords hashes. Then we just bruted these and got domain admin password. Spending weeks inside of your network we've managed to detect some fails we highly recommend to eliminate: 1. None of your employees should open suspicious emails, suspicious links or download any files, much less run them on their computer.
2. Use strong passwords, change them as often as possible (1-2 times per month at least). Passwords should not match or be repeated on different resources.
3. Install 2FA wherever possible.
4. Use the latest versions of operating systems, as they are less vulnerable to attacks.
5. Update all software versions.
6. Use antivirus solutions and traffic monitoring tools.
7. Create a jump host for your VPN. Use unique credentials on it that differ from domain one.
8. Use backup software with cloud storage which supports a token key.
9. Instruct your employees as often as possible about online safety precautions. The most vulnerable point is the human factor and the irresponsibility of your employees, system administrators, etc. We wish you safety, calmness and lots of benefits in the future. Thank you for working with us and your careful attitude to your security.