What Is Ransomware? Definition, Attack Stages, and Prevention Tips

Ransomware attacks have more than doubled in 2025, making it a top threat for 92% of industries. The number of active ransomware gangs has also spiked in the last year, with 65 groups currently operating – the busiest of them increasing their victims by more than 200% year-over-year.  

As the threat of ransomware grows increasingly urgent, understanding and addressing this risk has never been more important. To provide a foundational overview of ransomware, we’ll dive into what ransomware is, how it rose to prominence, and share strategies for preventing ransomware attacks.

What Is Ransomware in Cybersecurity?  

Ransomware is a type of malicious code that encrypts files or systems, rendering them inaccessible until a ransom is paid. Attackers often demand payment in cryptocurrencies to make tracing more difficult. 

Ransomware’s double-extortion model makes it particularly dangerous: in addition to locking files, many ransomware strains exfiltrate data, threatening to release or sell it if the ransom isn’t paid.   

Ransomware vs. Ransomware Attack

Though often used interchangeably, it’s important to distinguish between ransomware as malicious code and a ransomware attack, which is the event where it’s deployed. 

• Ransomware is the software itself  
• A ransomware attack is a coordinated campaign by threat actors to infiltrate a network, deploy ransomware, and extort victims 

Ransomware History: How Crypto Fueled Ransomware’s Rise 

Today, more than three-quarters of cybersecurity leaders say ransomware is their top concern, and it’s easy to see why – ransomware attacks were linked to 75% of system-intrusion breaches in 2024, and 44% of breaches overall. But these threats haven’t always been so pervasive.  

Ransomware’s roots stretch back to the late 1980s, but it wasn’t until the rise of crypto-ransomware in the 2010s that ransomware attacks exploded into a global epidemic. 

For decades, turning a security breach into a profit was complex and cumbersome – but the rise of cryptocurrency suddenly gave attackers an easy way to collect payments from victims while remaining anonymous and beyond authorities’ reach.  

The first modern ransomware attack was CryptoLocker, which grossed more than $27M in Bitcoin from 2013 to 2014. A decade later, ransomware victims paid a whopping $459.8M to cyber attackers in the first half of 2024 alone.  

Why Are Ransomware Attacks So Hard to Stop?  

Because the ransomware business is so profitable, cybercriminal groups can hire top talent to find zero days, create customized tools (which are harder to detect), and research advanced evasion techniques, like Hypervisor Jackpotting and bypassing EDRs.  

In other words, ransomware gangs have resources and skills that were once reserved for nation-states, meaning their victims need military-grade defenses to adequately defend themselves. Ransomware attacks are typically highly sophisticated; they often exploit legitimate network functions, making it incredibly difficult to detect ransomware before it’s too late.  

How Does Ransomware Work?  

While there are various types of ransomware, it most commonly works by encrypting files or systems after a period of clandestine movement through the network.  

Though ransomware attacks take many forms, they generally follow the same overall flow.

Stages of a Ransomware Attack  

Ransomware attacks typically occur in six stages:  

1. Reconnaissance: Attackers study the network, identify high-value assets, and search for vulnerabilities. 
2. Infection: They gain initial access – often through phishing emails, exploit kits, or compromised credentials. 
3. Escalation: Attackers move laterally through the network, escalating privileges to reach sensitive systems. 
4. Scanning: The malware enumerates files and systems to identify targets for encryption. 
5. Encryption: After identifying targets, attackers deploy ransomware to encrypt files or systems, often accompanied by the deletion of backups or shadow copies. 
6. Ransom: Attackers demand payment to provide the decryption key; many times, these demands are joined by threats of data exposure. 

Types of Ransomware  

Attackers use different techniques and monetization strategies during ransomware attacks, including: 

1. Encrypting Ransomware: The most common category of ransomware, this type does exactly what the name suggests – encrypts files, allowing attackers to demand ransom for decryption.  
2. Scareware: By displaying fake warnings or pop-ups, scareware tricks users into believing their system is infected to extort money. 
3. Screen Lockers: Aptly named screen lockers prevent users’ access to their screens until a ransom is paid.  
4. DDoS Extortion: Distributed denial-of-service (DDoS) attacks are threatened or executed unless payment is made. 
5. Ransomware-as-a-Service (RaaS): In this increasingly popular business model, developers sell or lease ransomware kits to other criminals. 

How To Prevent Ransomware Attacks

As we’ve established, ransomware attacks are not “one thing” – they’re sophisticated, complex, and well-orchestrated. This means you need to set up strong protection against any form of attack, accepting that breaches will occur.  

The best ransomware prevention strategies treat ransomware like an inevitability – and then rob it of its power to spread. A comprehensive ransomware defense should include proactive security controls and measures to streamline recovery.  

Proactive Security Controls  

Since ransomware attacks so often evade detection, preemptive controls provide the best protection:  

• Microsegmentation: Ransomware attacks need network access to propagate. From the very early stages of an attack, when they scan the internal network, to the latter ones, where they exploit a vulnerable exposed service or utilize compromised credentials to propagate. A segmented network leaves attackers stranded, so there is almost nothing they can do to spread. 
• MFA: Credentials are some of the most utilized “weapons” by attackers, who often find them all too easy to steal or crack. By protecting privileged access with MFA, defenders can significantly limit risk exposure.  
• Disabling unnecessary ports and services: Shutting down unused remote access protocols (like RDP and SMB) and enforcing strict access controls limits pathways and reduces ransomware’s attack surface. 
• Robust perimeter defenses: Solutions like next-generation firewalls (NGFW) and granular access controls minimize threats by strengthening North-South traffic protection.  

Measures to Streamline Recovery  

While preventing ransomware entirely is ideal, preparing for recovery is equally important. Best practices for streamlining recovery are: 

• Backup systems: Keeping regular, encrypted backups in an isolated environment disconnected from the main network simplifies recovery in case ransomware encrypts critical data. 
• Continuous monitoring and response: Watch for and respond to any suspicious activity in your network to detect emerging threats early. Note: Endpoint detection and response (EDR) systems alone won’t block lateral movement and protect against ransomware.  

Ransomware Recovery and Removal Best Practices  

Once ransomware is distributed, removal and recovery are critical. Speed matters – but so does caution. Acting too fast without a clear strategy can risk reinfection or damage recovery efforts. 

Here’s what to prioritize: 

Isolate Impacted Systems  

The first step in containing ransomware is cutting off the infection’s reach. Disconnect affected systems from the network to prevent the malware from scanning, encrypting, or jumping to other assets.  

If network segmentation is already in place, you’ll be able to quarantine infected zones more surgically, reducing the impact on the broader organization. 

Reinstall a “Clean” Operating System 

Even if you decrypt files or restore them from a backup, you can’t trust a compromised system. The safest approach is typically the same operation as one of the best methods for recovering a host: reinstall a clean OS. 

Don’t assume that removing ransomware software eliminates the threat. Many strains leave behind backdoors or secondary payloads designed to maintain persistence. 

Regenerate Credentials  

Data is not the only thing that needs to be “recovered” after ransomware is deployed – all credentials, secrets, API keys, and private keys may have been compromised, so they should also be regenerated to ensure the ransomware attack won’t hit again. 

Block Ransomware Instantly with Zero Networks  

Speed, stealth, and sophistication are ransomware’s greatest weapons. Because it spreads so quickly (and often without detection) once inside a network, traditional security solutions simply can’t keep up with ransomware attacks. That’s why Zero Networks built a solution that makes lateral movement impossible. 

By combining microsegmentation and granular identity-based access controls, Zero Networks stops ransomware attacks before they spread, ensuring attackers never escalate privileges or reach critical systems. Even if credentials are compromised, Zero’s just-in-time network-layer MFA ensures that those credentials cannot be utilized.  

In other words, if ransomware breaches the perimeter, it stays stuck, blocked from moving beyond its initial entry point. 

Take a self-guided product tour and see for yourself why the best ransomware protection isn’t reactive – it’s built-in.