Malware is code built to harm a computer or its user, for example by stealing data, locking files, or spreading further.
The category includes many families, and the shared fact is hostile intent rather than any single file type or delivery path.
How it works
Some programs encrypt files and demand payment, some steal passwords and files, and some quietly enroll the computer into further abuse.
Delivery can be a trick, a tainted download, a harmful ad, or a flaw that lets remote code run, and each path still ends in software the user did not want.
Naming the family helps responders choose containment, yet this page does not describe how to write or operate such code.
Defenses stack prevention, fast patching, least privilege, and backups that cannot be rewritten by the same account that opens mail.
Concrete examples
- A clinic cannot open patient files after a program encrypts the share and leaves a payment note on every desktop.
- A browser extension that posed as a coupon tool copies session cookies and sends them to an external server.
- A warehouse PC starts scanning the office network after a tainted USB stick was used to print a shipping label.
Protective measures
- Keep trusted backups offline or otherwise out of reach of the account people use to read mail and browse.
- Patch exposed software quickly and remove administrator rights from everyday interactive logins.
- Block untrusted macros, unexpected remote administration tools, and unsigned programs where the business allows that policy.
- Investigate the first suspicious host fully so a quiet spreader is not left on the same segment overnight.