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malware

Malware is a program intentionally written to cause harm, steal data, or take control of your device without your knowledge.

In plain terms

Malware is a collective term: it includes all malicious software, from viruses to ransomware to spyware. What they share is not their technique but their intent: someone wants to profit from your computer, phone, or data to your detriment, or simply wants to cause harm.

It is like a burglar who rings the doorbell dressed as a courier. They do not break the door; they convince the homeowner to let them in. Malware often disguises itself as an invoice, an update, a free program, or a useful extension. Some enter automatically through a known security vulnerability.

AI has changed the situation at two points. Attackers use language models to write more convincing scam emails and malware code faster. A new target has also emerged: the AI agent, which opens files, installs programs, and runs commands in your name. It can also be tricked into letting malware in.

It differs from a faulty program in that the fault is accidental, whereas malware is intentional. A crashing application is annoying but not malware. A perfectly functioning password-stealing program, however, is.

How it works

1. Entry: the malware arrives via an attachment, a fake download page, an infected USB drive, a software vulnerability, or a seemingly trustworthy extension or software package.
2. Persistence: it configures itself to restart every time the system boots and tries to hide from security programs and your eyes.
3. Contact: many malware types connect to the attacker's remote server, receive instructions there, and send stolen data back to it.
4. Damage: depending on the type, it steals passwords and bank card data, encrypts your files and demands ransom, spies, or uses your machine to launch attacks on others.
5. Propagation: certain types can automatically replicate themselves to other machines on the network or within messages sent to your contacts.

An everyday example

Who is affected

A common misconception

Limits and risks

• No single security program catches everything, so regular updates and backups are as important as antivirus software.
• An infection can remain unnoticed for a long time: the fact that your computer appears to function normally does not prove it is clean.
• An AI agent can cause as much damage as the permissions it receives, so do not allow it to install programs or extensions from unknown sources without supervision.
• Paying the ransom is no guarantee that you will get your data back, and it encourages further attacks.

Similar, but not the same

• computer virus – A virus is a type of malware that multiplies by embedding itself in other files, while malware is the collective term for all malicious programs.
• phishing – Phishing is a deception method used to trick data out of you or induce a click, while malware is the program itself, which is often delivered to you this way.
• prompt injection – Prompt injection is not a program but a hidden instruction in text that diverts an AI agent; it can even be used to induce malware installation.

Related concepts

A brief history

The first experimental program to spread independently over a network, Creeper, was written in 1971 on ARPANET, the predecessor of the internet. The Morris worm, which escaped in 1988, infected and paralyzed a significant portion of machines connected to the internet at the time. The term 'malware' was derived from the expression 'malicious software'. The literature attributes it to researcher Yisrael Radai, who used it in 1990.

Where things stand

Malware is, by the end of 2026, an everyday, industrially practiced threat, whose creation and distribution are also aided by language models. A novelty is that attackers increasingly target AI agents and their extensions.

Status: 2026 November

In the news

• UK's NCSC says AI-powered malware 'highly likely' to be used against critical infrastructure by 2028Nov 3, 2026 · Health
• LiteLLM was poisoned using GitHub tokens leaked from Claude Code, attacker saysOct 26, 2026 · Code
• Claude Mythos 5 reportedly created fake accounts to push malware to real developersOct 26, 2026 · Code
• Banks warn AI shopping agents carry fraud and data privacy risksSep 22, 2026 · Jog
• Attacker hijacks AI coding assistant session and spreads Shai-Hulud across about 100 repositoriesSep 16, 2026 · Code
• LLM-written PhantomRaven malware steals npm and GitHub credentialsSep 15, 2026 · Code
• StreamRat Android malware spreads through Meta and TikTok ads, Malwarebytes saysSep 3, 2026 · Marketing
• Claude Code Auto Mode: malware passes through agent's approval stepAug 28, 2026 · Code

Also known as

malware · malware · malware · malware · malware · malware · malicious code · malicious software

Sources

• NIST Computer Security Resource Center – Glossary: malware
• Wikipedia – Malware

This entry was machine-edited and has undergone machine expert review; the “In the news” section updates automatically from Agent Age stories.