Malware (malicious software) is any program or code designed to harm a device, steal data, spy on users or give attackers unauthorized control.
Types of malware
Malware is an umbrella term. The main families differ by how they spread and what they do:
- viruses infect other files, worms spread across networks on their own;
- trojans pretend to be useful software, including remote access trojans and bankers;
- ransomware encrypts or steals data for a ransom;
- spyware, keyloggers and infostealers collect personal data and passwords;
- rootkits and backdoors hide the attacker’s presence and keep access;
- bots join a botnet, miners secretly use the CPU for cryptocurrency, adware injects ads.
Modern malware often combines several functions and is delivered in stages: a small loader first, then the main payload.
Why malware matters for security
Malware is behind most cyber incidents, from stolen bank logins to shutdowns of hospitals and factories. Security labs register hundreds of thousands of new samples every day, many of them automatically repacked variants of known families designed to evade antivirus signatures. Criminals rent malware as a service, so even unskilled actors can run campaigns.
How to protect yourself
- Install software only from official sources and avoid cracked programs and fake updates.
- Keep the operating system, browser and apps updated.
- Use reputable security software; in companies, EDR with behavioural detection.
- Be careful with email attachments, macros and links; keep offline backups.
Synonyms:
malicious software, malicious program
