How We Stopped Brute-Force Attacks on a NAS
From Vulnerable to Fortified: How We Hardened a Client’s Synology NAS Against Brute-Force Attacks
As cyber threats continue to evolve throughout, one attack method remains surprisingly effective: brute-force attacks. While modern ransomware and phishing campaigns receive most of the attention, attackers still regularly target exposed NAS systems by attempting thousands of automated login attempts every day.
At Epis Technology, we recently worked with a client whose Synology NAS was experiencing persistent brute-force attack activity. What initially appeared to be a few failed login attempts quickly revealed a much larger security problem that could have resulted in unauthorized access, ransomware deployment, or data theft.
Fortunately, by implementing a layered security strategy, we transformed the NAS from a vulnerable target into a significantly more resilient platform.
The First Warning Signs
The client contacted us after noticing unusual alerts inside DSM and repeated notifications about failed login attempts.
Upon reviewing the logs, we found:
- Thousands of failed authentication attempts
- Repeated access attempts from multiple countries
- Continuous probing of administrator accounts
- Login activity targeting common usernames
- Suspicious traffic against exposed services
While the attacks had not yet succeeded, the volume and persistence indicated that the NAS was actively being targeted by automated attack tools.
Why NAS Devices Attract Attackers
Modern NAS systems often contain some of the most valuable data within an organization.
Typical NAS environments store:
- Financial records
- Business documents
- Client files
- Backups
- Surveillance footage
- Project archives
Attackers know that compromising a NAS can provide direct access to critical business information.
In many cases, compromised NAS devices also become entry points for broader network attacks.
Discovering the Real Vulnerabilities
The brute-force activity itself was not the biggest problem.
The larger issue was that the environment contained several security weaknesses:
- An exposed management interface
- Legacy administrator accounts
- Weak password policies
- Insufficient access restrictions
- Limited login protection settings
- Incomplete monitoring
These issues are common among NAS deployments that were configured years ago but never fully reviewed as security threats evolved.
Immediate Risk Reduction
Before implementing long-term improvements, Epis Technology focused on reducing the attack surface immediately.
We:
- Disabled unused accounts
- Renamed administrative accounts
- Restricted management access
- Reviewed exposed services
- Audited user permissions
- Updated DSM and installed packages
These initial actions significantly reduced opportunities for attackers.
Implementing Account Protection
One of the most effective defenses against brute-force attacks is limiting authentication attempts.
We configured:
- Automatic IP blocking
- Failed login thresholds
- Account lockout policies
- Enhanced password requirements
This helped prevent automated tools from repeatedly testing credentials.
Enabling Multi-Factor Authentication
Multi-factor authentication remains one of the strongest protections against unauthorized access.
We deployed MFA for:
- Administrators
- Remote users
- High-privilege accounts
Even if a password were compromised, attackers would still face an additional authentication barrier.
Leveraging Synology Security Advisor
To identify hidden weaknesses, we utilized Synology Security Advisor.
This allowed us to review:
- System configuration risks
- Weak account settings
- Service exposure
- Security recommendations
- Password policies
The assessment helped uncover several improvements that had previously been overlooked.
Restricting External Exposure
Many brute-force attacks succeed because management services are unnecessarily exposed to the internet.
To reduce risk, we:
- Limited external access paths
- Closed unused ports
- Restricted administrative services
- Improved remote access workflows
- Enhanced network segmentation
Reducing visibility significantly lowered attack opportunities.
Strengthening Backup and Recovery
Even with strong security controls, businesses must prepare for worst-case scenarios.
As part of the project, Epis Technology reviewed:
- Snapshot Replication settings
- Backup integrity
- Recovery testing procedures
- Disaster recovery workflows
This ensured the client could recover quickly if an incident ever occurred.
Monitoring for Future Threats
Security is not a one-time project.
We implemented additional monitoring for:
- Failed login spikes
- Suspicious IP activity
- Administrative changes
- Unauthorized access attempts
- Storage and backup alerts
Ongoing visibility helps detect threats before they become serious incidents.
The Results
After completing the security hardening process, the client experienced:
- Dramatically reduced attack exposure
- Better visibility into login activity
- Stronger administrative controls
- Improved recovery readiness
- Greater confidence in their Synology environment
Most importantly, the NAS remained operational and secure despite ongoing attack attempts from automated threat actors.
What Businesses Are Learning
One of the biggest cybersecurity lessons organizations continue learning is that storage systems must be treated as critical security assets.
Modern NAS deployments require:
- Multi-factor authentication
- Access controls
- Security monitoring
- Backup protection
- Network segmentation
- Regular security reviews
Organizations that rely solely on passwords are increasingly vulnerable to automated attacks.
About Epis Technology
Epis Technology helps organizations secure and optimize Synology environments through cybersecurity hardening, backup protection, disaster recovery planning, and infrastructure modernization. The company specializes in Synology consulting, Microsoft 365 and Google Workspace backups, large-scale storage solutions, fully managed PC backups, and enterprise data protection.
By combining proactive monitoring, layered security controls, and resilient backup architecture, Epis Technology helps businesses protect their most valuable data against modern cyber threats.