How to Harden NAS Security Against Bruteforce & Ransomware

Make NAS Security Stronger Against Ransomware and Brute-Force

More and more, automated brute-force attacks and ransomware campaigns are going after NAS platforms because they hold all of your data, backups, and shared workflows. The good news is that most successful compromises still depend on a few well-known weaknesses, such as exposed services, weak identity controls, delayed patching, and recoveries that were never tested. You can use the following practical hardening playbook in phases without stopping staff from getting to work every day. See how to protect your Synology NAS from ransomware

1) First, make your attack surface smaller

Most NAS breaches happen when the device is directly connected to the internet through an admin port, SMB, SSH, or a public web portal. Your first goal is to cut down on the number of “things the internet can talk to.”
Remove port forwards for DSM/admin portals and management services that come in. If you need to access something from a distance, use a private tunnel (VPN or Zero Trust access proxy) instead of open ports.
Turn off services you don’t use, like Telnet, old SMB modes, extra web apps you don’t need, and legacy protocols.
Disable UPnP on the edge router so that devices can’t publish themselves without your knowledge.
Separate networks: put NAS management on one VLAN, user access on another, and IoT devices and cameras on their own VLAN.

This change alone makes it much harder for attackers to use “scan, find, password-spray” methods.

2) Lock down who you are and how you log in

Brute-force and password-spraying work best on accounts that are easy to guess and can be tried an unlimited number of times.
Change the names of or turn off default admin-style accounts. Each administrator should have their own named admin account.
Require MFA for all privileged users, and then add it for all remote users.
If your identity provider supports it, set a strong password policy and block passwords that have been used before or that have been hacked.
Set up automatic blocking for repeated failed logins and combine it with allowlists (only known office/VPN IP ranges can access admin interfaces).
Lower privileges: Most users shouldn’t have admin rights, and service accounts should only have the permissions they need to do their job.

These controls follow common advice for dealing with ransomware that says multi-factor authentication (MFA) and stricter access controls are two of the most important ways to protect yourself. View Why Businesses Must Implement Multi-Factor Authentication

3) Patch like it’s part of security, because it is

Attackers often use weak passwords and known security holes in services that are open to the public.

Quickly install OS and package updates, especially those that have to do with authentication, remote access, web services, or file sharing.
Look at what is facing the internet and put those parts at the top of your list.
Add alerts so you can see when patch compliance is getting worse.

4) Set “blast-radius” limits so that one mistake doesn’t turn into a disaster

Even well-run places can have their credentials stolen or an endpoint hacked. Make sure that your NAS doesn’t lose everything if someone steals a password.
For shares that change a lot, use snapshots and keep more than one restore point.
Backup repositories should be separate from user shares, with different credentials and stricter permissions.
Don’t map backup storage to a normal drive letter or common share for regular users.
Use write-protected or unchangeable targets whenever you can. This will stop ransomware from encrypting or deleting backups after it gets there.

5) Make sure you can recover, not just make “backups.”

A lot of companies find out too late that they had backups, but they were incomplete, encrypted by hackers, or hard to restore quickly. Modern ransomware advice stresses the importance of keeping backups that are not connected to the internet or are otherwise safe and testing restores. Read a real Synology ransomware incident that exposed common security mistakes

A useful starting point for recovery:

Make sure that at least one copy can’t be accessed with normal user credentials.
Every month, we do a small file restore test and every three months, we do a “system-level” restore drill for important services.
Use the 3-2-1 method: make multiple copies on different media and keep one copy offsite. Master the 3-2-1 Backup Strategy

All about Synology: encryption and immutability

If you use Synology, you can make it more resilient by using the new features in Synology DiskStation Manager, but only if you set them up right. Synology’s immutable options use WORM-style controls, like WriteOnce shared folders and Immutable Snapshots, to keep data safe from being changed or deleted during the retention window. Learn how immutable snapshots stop ransomware attacks on NAS systems. This is especially useful for regulated retention and ransomware recovery. When you add encryption at rest (at the volume or folder level) and stricter access controls, you lower the risk of a breach and the damage that would happen if a device is stolen or an account is misused.

6) A simple way to respond to an attack if you think one is happening

Isolate the affected endpoint or NAS network segment. Don’t turn it off right away unless you have to.
Keep logs and write down the times, suspicious IPs, and accounts that were affected.
From a clean admin workstation, reset credentials, change API keys, and end sessions.
Restore from snapshots or backups that can’t be changed to clean storage, and then slowly add services back in.
After an incident, harden the system by removing vulnerabilities, requiring MFA everywhere, and checking backups again.

About Epis Technology

Epis Technology helps businesses overcome complex data protection challenges by designing secure Synology environments with reliable recovery strategies. Their team implements ransomware-resistant backup systems, including protection for Microsoft 365, Google Workspace, and fully managed PC backups. Discover solutions for modern data protection challenges with Epis Technology. Through continuous monitoring, documented recovery procedures, and regular restore testing, Epis Technology ensures that NAS infrastructures remain secure, scalable, and ready for rapid recovery during critical incidents.