Ransomware: What It Is, How It Works, and How to Prevent It
Imagine arriving at work to find every file encrypted and a message demanding bitcoin for the key. This nightmare scenario happens to thousands of organizations every day. Ransomware is one of the most devastating cyber threats, but understanding it is the first step to preventing it.
What is ransomware?
Ransomware is malware that encrypts your files and demands payment for the decryption key. Without that key, your data is effectively gone — locked behind military-grade encryption.
The name says it all: your data is held for ransom. Pay up or lose everything. And even if you pay, there’s no guarantee you’ll get your files back.
Modern ransomware has become a massive criminal industry. Organized groups operate like businesses, with customer support for victims, affiliate programs, and continuous development.
How ransomware infects systems
Phishing emails
The most common entry point. An innocent-looking email with an attachment — an invoice, a resume, a shipping notification. Open it, and malware installs silently.
Sophisticated phishing is hard to spot. The email might appear to come from a colleague, referencing real projects. The attachment looks like a normal document.
Exploiting vulnerabilities
Unpatched software is an open door. Attackers scan for known vulnerabilities in internet-facing systems. One unpatched server can be the entry point for an entire network compromise.
Remote Desktop Protocol (RDP) exposed to the internet is particularly dangerous. Many ransomware attacks begin with brute-forcing weak RDP credentials.
Drive-by downloads
Visiting a compromised website can trigger malware download without you clicking anything. Exploit kits detect vulnerable browsers or plugins and deliver payloads automatically.
Malvertising — malicious ads on legitimate websites — can trigger these attacks even on reputable sites.
Supply chain attacks
Attackers compromise software you trust. A legitimate update from a trusted vendor delivers ransomware because the vendor’s systems were hacked.
These attacks are particularly insidious because victims did nothing wrong except trust their software suppliers.
What happens during an attack
Initial access
The malware establishes a foothold, often silently. It might wait days or weeks while attackers explore the network and identify valuable targets.
Lateral movement
From the initial infected system, attackers spread through the network. They gather credentials, identify file servers and backup systems, and position themselves for maximum impact.
Privilege escalation
Attackers seek administrator access. With domain admin credentials, they can deploy ransomware everywhere simultaneously.
Exfiltration
Increasingly, attackers steal data before encrypting it. This enables “double extortion” — pay to decrypt your files AND to prevent data from being leaked publicly.
Encryption
Finally, the encryption deploys. All accessible files are locked. A ransom note appears explaining how to pay, usually in cryptocurrency.
Should you pay the ransom?
The FBI and security experts generally recommend against paying. Payment encourages more attacks and funds criminal enterprises. There’s no guarantee you’ll get working decryption keys.
But the decision isn’t always simple. For organizations facing existential threats — hospitals unable to access patient records, manufacturers with production halted — paying might seem like the only option.
Before deciding: – Report to law enforcement; they may have decryptors available – Check if researchers have cracked that specific ransomware – Consider whether your backups can recover the business – Evaluate whether decryption actually works for that ransomware strain
How to prevent ransomware
Backup, backup, backup
This is your insurance policy. Regular backups, stored offline or in immutable storage, let you recover without paying.
Follow the 3-2-1 rule: three copies, two different media types, one offsite. Test your backups regularly — you need to know they actually work.
Critical: keep at least one backup disconnected from your network. Ransomware specifically targets backup systems.
Patch religiously
Most successful ransomware attacks exploit known vulnerabilities. Patches exist; they just weren’t applied.
Prioritize internet-facing systems and known actively-exploited vulnerabilities. Automated patch management helps keep everything current.
Limit access
Apply the principle of least privilege. Users shouldn’t have admin rights they don’t need. Network segments should be isolated where possible.
If ransomware can’t reach your critical systems, it can’t encrypt them.
Train your users
Phishing remains the top entry point. Regular training helps employees recognize suspicious emails, attachments, and links.
Simulated phishing tests identify who needs additional training and keep awareness high.
Deploy endpoint protection
Modern endpoint security detects ransomware behavior even from unknown variants. Look for solutions with ransomware-specific protections like monitoring for mass file encryption.
Secure RDP
If you need remote access, don’t expose RDP directly to the internet. Use VPN or a secure gateway. Require strong passwords and multi-factor authentication.
Better yet, use modern alternatives like Zero Trust Network Access (ZTNA) that verify every connection.
Responding to ransomware
If ransomware hits despite your defenses:
- Isolate immediately: Disconnect infected systems from the network to stop spread
- Don’t turn systems off: Evidence may exist in memory that helps investigation
- Assess scope: Determine what’s affected and what’s clean
- Notify stakeholders: Legal, executives, possibly customers and regulators
- Engage experts: Incident response professionals can help contain and recover
- Report to law enforcement: They track ransomware groups and may have resources to help
- Restore from backups: Once the threat is contained, begin recovery
The bottom line
Ransomware is a business for criminals, and business is booming. Any organization can be a target.
Prevention isn’t about any single control — it’s layers. Backups protect against the worst outcomes. Patching closes entry points. Training reduces human error. Endpoint protection catches what slips through.
Prepare as if an attack is inevitable. With proper preparation, ransomware becomes an expensive inconvenience rather than an existential crisis.