# What is malware?

Malware is any software written to do harm on a computer or network: steal data, encrypt files for ransom, spy on users, or give an attacker remote control. Viruses, worms, trojans, ransomware and spyware are all kinds of malware. Most malware arrives through an email attachment, a malicious link, a fake download or an unpatched service exposed to the internet. Antivirus and EDR tools look for it on each computer. Once malware is running, it usually has to talk over the network, to its operator or to other machines, and that traffic is what a network sensor such as NetSenX watches for.

FAQ: [What is…? Network and security terms](https://netsenx.com/en/faq/glossary) · https://netsenx.com/en/faq/what-is-malware

## Read next

- https://netsenx.com/en/what-is-ndr
- https://netsenx.com/en/problems-we-solve

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