What is Malware?

What it is

Malware is a broad category of harmful software. It includes things like ransomware, spyware, trojans, worms, and other malicious programs.

Its purpose depends on the attacker. Some malware steals data, some disrupts systems, and some opens the door for further attacks.

How it works

Malware can arrive through phishing links, unsafe downloads, infected attachments, compromised websites, or software vulnerabilities.

Once it gets onto a device or system, it may install itself, hide, spread, steal information, damage data, or wait for instructions from an attacker.

Why it matters in real life

Malware matters because it affects individuals, businesses, schools, governments, and healthcare systems. The harm can include stolen passwords, financial fraud, downtime, or data loss.

It also matters because many common cyber incidents start with malware or involve malware somewhere in the attack chain.

Common misconceptions

A common misconception is that malware only comes from obviously suspicious files. In reality, attackers often disguise malware as ordinary documents, apps, updates, or links.

Another misconception is that malware only affects old computers. Modern devices and organizations can still be affected if defenses fail or people are tricked.

Related questions

What to learn next

Sources

• CISA Malware Resources
• NIST Glossary: Malware