How to stop ransomware attacks before they start

No organisation wants to deal with a ransomware attack – but they do happen and preparation makes all the difference. If you’re wondering how to prevent ransomware attacks, it’s essential to understand how they start, why they spread, and which controls block them early. 

If you are reading this because you think you have experienced a ransomware incident and are unsure how to deal with it, contact Zensec immediately.

In 2025, we’re witnessing a common pattern among ransomware incidents: they combine data theft with file encryption. Attackers often enter through phishing emails, exposed remote services, weak credentials, and unpatched software. In this post, we’ll reveal some prevention-first practices, role-based responsibilities, network safeguards, and testing and validation. You’ll also learn which actions to take if you identify any suspicious activity. 

Why ransomware prevention is a must 

Ransomware is malicious software that encrypts files and demands payment for a decryption key. Many operations also steal data and threaten to publish it to increase pressure on victims.

Prevention costs far less than recovery. When ransomware hits, organisations can deal with weeks of downtime and have to invest in various recovery activities. These include forensic investigations, legal fees, system rebuilds, and customer notifications. 

Recovery is an intensive process that covers forensics, incident response, notifying the relevant regulatory boards, and many other vital tasks. Permanent data loss happens frequently when backups are incomplete, corrupted, encrypted by attackers, or never tested for restoration.

How ransomware attacks start and spread

Ransomware operators are opportunists, and they’ll always look for easy entry into your systems. Popular entry points include fake emails that trick employees into opening files or clicking links, public systems that haven’t been patched, and remote access with weak passwords or no multifactor authentication.

After gaining access, the attackers will explore internal networks to find valuable systems and data. Movement between machines often uses built-in tools like Remote Desktop, PowerShell, SMB, or scheduled tasks to stay hidden from security tools.

Privilege escalation gives attackers higher rights than normal users. Access at the administrator or domain administrator level allows mass deployment of ransomware, theft of sensitive data, and disruption of backup systems.

Common attack vectors include:

• Phishing emails: Malicious attachments or links that install malware when opened

• Vulnerable systems: Unpatched software and operating systems with known security flaws

• Remote access: Weak RDP and VPN credentials that attackers can guess or steal

• Supply chain: Compromised third-party software that contains hidden malware

Eight essential steps to prevent ransomware attacks

Ransomware attacks can be devastating for organisations of all sizes, but knowing how to shield your systems can significantly decrease their risks. 

Following these eight steps can limit potential damage and protect your company. 

1. Enforce multifactor authentication

Multifactor authentication (MFA) is a login process requiring two or more proofs, like a password, an app code, or a hardware token. The extra factor blocks unauthorised access if a password gets stolen or guessed through automated attacks.

Remote access portals like VPN and RDP gateways, email platforms, and privileged or administrator accounts should be your first priority when adding MFA. Coverage across cloud services and on-premises systems reduces the chance of a single weak point.

2. Patch internet-facing systems rapidly

Vulnerability management finds, ranks, and fixes software flaws based on risk levels. Prioritising risks means that you can identify issues with high severity, known exploitation, and broad exposure to the internet.

Internet-exposed systems carry the highest attack risks, so rapid patch cycles and maintenance windows are standard practice. Automation with central patch tools and vendor auto-updates reduces the gap between security updates and deployment.

3. Segment critical networks and disable unused ports

Network segmentation divides systems into separate zones so ransomware can’t move freely across an environment. Access between zones follows least privilege principles, allowing only traffic that business processes require.

Hardening hosts and network devices by turning off unused ports and services reduces potential entry points. Access control lists on switches and firewalls limit lateral movement between network segments.

4. Deploy advanced email and web filtering

Email filtering is a valuable tool, as it scans attachments and links before delivery – blocking malicious content. Techniques like sandboxing and link rewriting lower the risk from weaponised files and phishing websites.

Web filtering and protective DNS block connections to known harmful or newly registered domains. Organisations route DNS traffic through controlled resolvers and apply the same policies on and off the corporate network for consistency.

5. Harden endpoints with EDR and application control

Endpoint detection and response (EDR) monitors behaviour on laptops and servers to flag suspicious actions like mass file encryption. EDR can isolate a device, stop malicious processes, and collect evidence for investigation.

Application control allows only approved software, limiting untrusted scripts and installers. Features like controlled folder access restrict changes to key directories that ransomware typically targets.

6. Keep offline immutable backups and test restores

Immutable backups are write-once copies you can’t alter or delete within a set retention period. Offline or logically isolated storage, such as object lock, WORM media, or tape, prevents ransomware from reaching backup data.

Regular restore tests confirm that backups are complete and usable. Testing also verifies recovery time objectives and exposes gaps in configuration or documentation before an actual incident occurs.

7. Train employees to recognise phishing

One of the most effective ways to prevent phishing scams is to ensure your employees know how to spot them. 

Security awareness training explains how phishing works and how to spot warning signs in emails, messages, and calls. Short, regular sessions and simulated campaigns help reinforce pattern recognition skills.

Clear reporting paths, like a dedicated mailbox or report button, make it easy to raise concerns quickly. Just-in-time prompts at risky moments, such as external email banners, support good security decisions.

8. Exercise your incident response and backup plans

Exercises and tabletop drills walk through realistic ransomware scenarios with IT, security, legal, communications, and leadership teams. Practice builds familiarity with roles, contacts, and technical steps before a real incident.

Organisations track time to detect, contain, and restore during each exercise. Findings feed updates to playbooks, escalation paths, backup procedures, and security tool configurations.

How to protect your network against ransomware

Network-level defences and careful architecture reduce blast radius and limit attacker movement. Controls at the perimeter, between internal zones, and around backups create multiple barriers to ransomware.

Control remote access and RDP exposure

Remote Desktop Protocol exposed directly to the internet is a frequent entry point for intrusions. RDP is commonly placed behind a VPN that enforces multifactor authentication and device posture checks to restrict access to trusted users and devices.

Access to high-value systems often flows through jump hosts or bastion services instead of direct connections. IP allow lists restrict who can reach those gateways in the first place.

Monitor east-west traffic for anomalies

East-west traffic is communications that move inside the network between internal systems. Ransomware operators rely on this path for lateral movement after gaining initial access.

Network detection and response tools, intrusion detection systems, and NetFlow analytics help spot unusual patterns. Common warning signs include sustained SMB authentication failures, sudden spikes in remote management protocols, and command-and-control beacons to external hosts.

Block malicious domains with protective DNS

Protective DNS uses filtering to stop lookups and connections to domains linked to malware, phishing, and command-and-control infrastructure. Filters also cover newly registered domains that frequently appear in ransomware campaigns.

DNS traffic is commonly routed through controlled resolvers only, with other DNS paths blocked at network boundaries. This approach standardises policy and prevents endpoints from bypassing protections.

Testing and validating your ransomware defences

Testing confirms that controls continue to work correctly and remain effective in the long term. A balanced program covers vulnerability scanning, configuration audits, and penetration testing.

Vulnerability scanning uses automated tools to look for known weaknesses in operating systems, applications, devices, and cloud services. Risk-based reporting ranks findings by severity, exploitability, and exposure to prioritise remediation efforts.

Configuration audits compare systems to hardened baselines. Examples include verifying MFA enforcement, disabling exposed RDP, confirming EDR and application control are active, and checking patch and logging policy settings.

Backup validation confirms both data integrity and the practicality of recovery steps. Tests cover file-level restores, application-aware restores for databases and email, full system rebuilds, and bare-metal recovery scenarios.

Immediate actions to take if you detect ransomware activity

Ransomware detection triggers an emergency response, with the priorities being speed, containment, and preservation of evidence for investigation and recovery.

Organisations should always isolate affected systems from the network to stop further spread. Segmentation at switches and firewalls limits traffic from suspect hosts to only what containment requires. Disabling suspected accounts, resetting passwords, and rotating authentication keys are essential. 

It’s a good idea to review privileged accounts for recent changes, unusual group memberships, and new delegations that attackers may have created. Wherever possible, you should preserve forensic evidence while isolation occurs. 

Memory dumps, disk images, and logs are captured before reimaging or powering off to retain details of the intrusion path and attacker actions.

Strengthen your ransomware defence with expert support

Zensec specialises in ransomware prevention and incident response, operating 24/7 across the UK and beyond. As an NCSC Assured Service Provider and ISO27001-accredited company, Zensec builds, validates, and maintains the controls and processes outlined in this guide.

When an incident occurs, our experts deploy quickly, offering remote containment and on-site support. 

Our first-hour actions follow procedures insurers and law enforcement set for triage, evidence preservation, and containment.

Contact us immediately for urgent ransomware recovery support.

FAQs about preventing ransomware attacks

What is the most effective way to prevent ransomware attacks?

Ransomware attacks are complex, and no single control will prevent them. Instead, you should adopt a multi-pronged defence, incorporating multiple controls. 

These include multifactor authentication, regular patching, network segmentation, email filtering, endpoint protection, offline backups, employee training, and incident response planning.

How often do organisations experience ransomware attacks?

Ransomware attacks occur frequently across organisations of all sizes, with many incidents going unreported. The actual frequency varies significantly by industry, security maturity, and threat exposure.

Can ransomware spread through network backups?

Yes, ransomware can reach network-attached backup systems if not properly isolated. Offline backups, immutable storage, and one-way replication help protect backup data from encryption or deletion.

Do small businesses need the same ransomware protections as large enterprises?

Small businesses face similar ransomware threats but can implement scaled-down versions of the same core controls. 

As a small business, your priorities should include MFA, patching, backups, email filtering, and basic employee training rather than enterprise-grade security operations centres.

How long does it typically take to recover from a ransomware attack?

Recovery time varies widely based on preparation, backup quality, and attack scope. Organisations with tested backups and response plans may recover in days, while those without proper preparation often face weeks or months of downtime.

Ransomware may be evolving, but you don’t have to face it alone. Get in touch with Zensec and start building resilience, validate your defences, and respond with confidence.