What Is Ransomware? How It Works and How to Stop It

Ransomware is a type of malicious software (malware) that encrypts a victim's files or entire systems, then demands a ransom payment — usually in cryptocurrency — in exchange for the decryption key. It has become the single most disruptive and costly cyber threat facing organizations, capable of shutting down hospitals, pipelines, schools and entire city governments in hours.

Modern ransomware is no longer the work of lone hackers. It is a professionalized criminal industry with affiliates, support desks, negotiators and recurring "business models." Understanding how it works is the first step to defending against it — and it's one of the most frequently reported topics in any threat intelligence feed.

How a ransomware attack works

A typical ransomware attack unfolds in stages, much like any intrusion:

1. Initial access. Attackers get in — commonly through phishing emails, stolen or weak credentials (especially on exposed remote-access services), or by exploiting an unpatched vulnerability on an internet-facing system.
2. Establish foothold and escalate. They install tools, harvest credentials, and escalate privileges to gain administrative control.
3. Reconnaissance and lateral movement. They map the network and move from system to system, identifying the most valuable data and the backups.
4. Exfiltration. Before encrypting, most modern groups steal a copy of sensitive data to use as additional leverage.
5. Encryption (detonation). They deploy the ransomware across as many systems as possible at once, encrypting files and dropping a ransom note.
6. Extortion. The victim is told to pay by a deadline, often with the threat of leaking the stolen data or increasing the price.

Double and triple extortion

Early ransomware simply encrypted data, so organizations with good backups could often recover without paying. Criminals adapted with double extortion: they steal data before encrypting, then threaten to publish it on a leak site if the ransom isn't paid. Now even a victim with perfect backups faces a data-breach disaster.

Some groups push further into triple extortion — adding pressure such as launching denial-of-service attacks, or directly contacting the victim's customers, partners and the media. The trend has been a steady shift from "encryption" toward pure data extortion, where some groups skip encryption entirely and simply threaten to leak stolen data.

Ransomware-as-a-Service (RaaS)

The explosion in ransomware is driven by the Ransomware-as-a-Service model. Skilled developers build and maintain the ransomware and leak infrastructure, then rent it to affiliates who carry out the actual intrusions. Profits are split — affiliates often keep the majority. This lowers the barrier to entry dramatically: an attacker no longer needs to write malware, only to break into a network.

RaaS also makes the ecosystem resilient. When one brand gets disrupted by law enforcement, affiliates simply move to another. This is why tracking ransomware groups, their affiliates and their TTPs is a core threat-intelligence activity.

Notable ransomware groups

The ransomware landscape changes constantly as groups rebrand, splinter and get taken down, but families like LockBit, ALPHV/BlackCat, Cl0p, Conti (now dispersed) and others have caused billions in damage. Many specialize: some focus on healthcare, some on managed-service providers (to hit many victims at once), and some on exploiting a single widely used vulnerability across thousands of organizations simultaneously. Staying current on which groups are active and how they operate is essential, which is why ransomware reporting features so heavily in our live threat intelligence feed.

How to prevent ransomware

No single control stops ransomware, but layered defenses dramatically reduce risk:

• Patch fast. Prioritize internet-facing systems and actively exploited vulnerabilities.
• Harden identity. Enforce phishing-resistant multi-factor authentication, especially on remote-access services, and apply least-privilege access.
• Back up — properly. Maintain offline, immutable, tested backups that attackers can't reach or encrypt.
• Segment the network. Limit lateral movement so one compromised host doesn't doom the whole estate.
• Deploy EDR. Endpoint detection can catch the pre-encryption stages — credential theft, lateral movement, suspicious tooling.
• Train staff. Phishing remains a top entry point; awareness reduces the click rate.
• Use threat intelligence. Know which groups target your sector, and hunt for their TTPs proactively.

What to do if you're hit

If ransomware strikes, the priorities are containment and a measured response:

1. Isolate affected systems immediately to stop the spread.
2. Activate your incident-response plan and engage specialists and legal counsel.
3. Preserve evidence for investigation and potential law-enforcement involvement.
4. Assess scope — what was encrypted, what was stolen.
5. Restore from clean backups where possible.

Authorities generally discourage paying the ransom: it funds further crime, doesn't guarantee recovery, and may carry legal risk. Whether to pay is a difficult business and legal decision that should never be made on the fly — which is exactly why having a tested plan beforehand matters so much.

Common ransomware myths

Several persistent misconceptions leave organizations exposed. Clearing them up changes how you defend:

• "We're too small to be a target." Small and mid-sized organizations are attacked constantly, precisely because they tend to have weaker defenses. Affiliates often cast a wide net, exploiting any vulnerable organization they find rather than hand-picking victims.
• "Backups alone will save us." Backups are essential, but double extortion means attackers steal data before encrypting. Even a flawless restore doesn't undo a data breach — and attackers specifically seek out and delete backups before detonating.
• "Paying the ransom makes the problem go away." Payment doesn't guarantee a working decryptor, doesn't recover stolen data, marks you as a willing payer for future attacks, and may carry legal risk. Many victims who pay are hit again.
• "It's an IT problem." A serious ransomware incident is a business crisis touching legal, communications, finance and leadership. Treating it as purely technical leaves an organization unprepared for the decisions it will actually face.
• "Antivirus will stop it." Modern ransomware operators are hands-on-keyboard and use legitimate tools to evade signature-based defenses. Behavior-based EDR and the discipline of threat hunting catch far more than antivirus alone.

The thread connecting these myths is the belief that a single control or assumption is enough. In reality, ransomware resilience comes from layered defense, rehearsed response, and the recognition that prevention will sometimes fail — so detection, segmentation and recovery must be ready when it does.

The bottom line

Ransomware has evolved into a professionalized extortion industry built on RaaS and double extortion. Defending against it requires preparation across the whole attack chain — strong identity, fast patching, immutable backups, segmentation, endpoint detection and good intelligence. Because the landscape shifts weekly, staying informed is part of the defense: our live threat intelligence feed tracks ransomware campaigns, new groups and active exploitation from dozens of authoritative sources, ranked by priority.