What is ransomware and how to protect your files and servers?

Published on 2026-10-20 by frfrand

Ransomware explicado desde cero: secuestro de archivos, robo de datos, copias de seguridad, señales y qué hacer ante un incidente.

Ransomware is a type of malicious software used to block access to information or systems, frequently through encryption, with the aim of demanding money. In many modern incidents, there is also the threat of publishing stolen data.

The typical image is a screen demanding a ransom. But the real problem often starts earlier: a stolen access, an uncorrected vulnerability, or a misconfiguration that allows the attacker to enter.

An example that is easy to understand

Imagine a company with ten employees. All of them work on a shared folder where they store invoices, contracts, and customer documents. One morning those files can no longer be opened. A note appears indicating that they must pay to recover access.

Even if the company has money to pay, there is no guarantee that they will recover the files or that the stolen information will not end up published. The response needs to think first about stopping the damage and rebuilding systems securely.

How does this type of attack arrive?

There is no single path. It can begin with compromised credentials, a fraudulent message, an unprotected remote access, or vulnerable software.

Once inside, attackers can attempt to extend access to other systems, look for valuable information, or disable defenses. Not all incidents follow exactly the same sequence.

That is why it is not advisable to speak of ransomware as if it were simply "a weird file downloaded by an employee". Account and infrastructure security also matters.

What are offline backups?

A good backup should allow data to be restored even if the main machine fails. If the only backup is permanently connected to the same system and uses similar permissions, an attack could affect it as well.

CISA recommends keeping disconnected or properly protected copies and testing restoration, not just checking that files called backup exist.

It is also advisable to keep historical versions. If a malicious modification is replicated before someone detects it, the most recent copy may contain the problem.

Does an antivirus prevent everything?

No. Protection programs can detect many threats, but real defense combines updates, access control, segmentation, strong authentication, monitoring, and backups.

Having a firewall is not enough either if you expose a vulnerable application or use reused passwords.

What to do if you suspect an intrusion?

The first thing is to organize the response: identify affected systems, contain the spread, and preserve useful information for investigation.

Avoiding impulsive changes can be important, especially if deleting a file or restarting a machine destroys evidence. In business environments, it is advisable to activate the incident procedure or have specialized assistance.

Recovery usually requires verifying which systems are clean, rotating compromised credentials, and restoring from reliable backups. Restoring files without fixing the entry point leaves the possibility of another intrusion open.

Why paying is not a recovery plan?

Because the attacker may not provide a useful tool, files may remain damaged, and stolen data may continue to circulate. Additionally, there are legal, business, and regulatory implications.

An organization's priority should be to prepare beforehand: knowing which services are essential and how long they can remain offline.

What should a small administrator review?

Inventory of services, privileged accounts, authentication, updates, network permissions, and actual restoration capacity. A periodic recovery test reveals failures that a nice list of "backups performed" does not detect.

And at ArduMaker?

An application hosted on an ArduMaker VPS needs the same discipline: limit access, maintain software, protect credentials, and back up data in an environment that can be recovered if the server is compromised. The deployment platform does not replace an incident plan.

In summary: ransomware is not just about encrypting files; it is a threat to business continuity and information. The best response starts with prevention, tested backups, and clear procedures.

Sources: CISA StopRansomware Guide · What is a backup.