What is Malware?

Malware = "malicious software." It's the umbrella term for any program designed to harm you, your device, or your data. Here's what the different kinds are and how to deal with them.

The main types

Virus

Original kind. Attaches itself to legitimate programs and spreads when those programs run. Modern PCs see fewer "viruses" in the classic sense; most malware now is something else.

Ransomware

Encrypts your files and demands payment to unlock them. Devastating if you don't have backups. Common targets are businesses, but home users get hit too.

Examples: WannaCry, LockBit, Conti.

Spyware

Watches what you do and reports back. Keyloggers (records what you type, including passwords), screen capturers, banking trojans (waits until you log into your bank).

Adware

Floods you with ads, redirects browsers, injects sponsored search results. Annoying more than dangerous, but the line is blurry.

Trojan

Pretends to be useful software. The classic one is "free movie player" that's actually malware. Trojans are how a lot of other malware gets installed.

Worm

Spreads automatically across networks without needing a user to click anything. Famous historical worms: ILOVEYOU, Conficker.

Rootkit

Hides itself deep in your operating system, making it hard to detect or remove. Less common on consumer devices but very serious when present.

Cryptojacker

Uses your computer's processing power to mine cryptocurrency, slowing you down. Sometimes you find out because your laptop fan is always running.

How malware gets on your devices

Phishing

Email or text with a malicious link or attachment. You click, malware downloads. How to spot phishing.

Pirated software

Cracked versions of Adobe Photoshop, Microsoft Office, games. Often bundle malware.

"Free" programs from sketchy sites

Free PDF converter, free YouTube downloader, free screen recorder. Some are legitimate, but many bundle adware or worse.

Compromised websites

Even normal websites get hacked. Browser exploits rarer than they used to be (Chrome and Edge sandbox web content) but still happen.

USB drives

"Found" USB sticks, infected drives from a friend, USB cables in airport USB charging stations (juice jacking).

Malicious browser extensions

Chrome and Firefox extensions can spy on every website you visit. Stick to well-known extensions with thousands of users.

Signs of infection

• Computer suddenly very slow
• New toolbars or browser homepage you didn't install
• Popups when not browsing
• Programs crashing frequently
• Antivirus disabled and you don't remember disabling it
• Friends getting weird messages from your accounts
• Files with extensions like .locked, .encrypted, .cry
• Files inaccessible or renamed
• Unknown programs starting at boot
• Your battery drains way faster than normal
• Your cellular data usage spikes unexpectedly

How to clean an infection

1. Disconnect from internet to stop it from spreading or sending more data out
2. Boot into Safe Mode on Windows (hold Shift while clicking Restart, then Troubleshoot > Advanced > Startup Settings > Safe Mode with Networking)
3. Run Microsoft Defender full scan (not quick scan)
4. Run Malwarebytes free as second opinion
5. Quarantine and remove anything they find
6. Change important passwords from a different (clean) device
7. Restore files from backup if ransomware encrypted them. Don't pay the ransom; often you don't get them back anyway
8. Consider a full Windows reset if you can't be sure it's clean

How to avoid getting infected

1. Use Microsoft Defender (already installed on Windows)
2. Keep Windows, browser, and apps updated
3. Don't click suspicious links in email or texts
4. Don't install pirated software
5. Download apps from official sources (Microsoft Store, App Store, Play Store, or directly from the company's site)
6. Use a password manager and 2FA so even if one account is compromised, others stay safe
7. Back up your important files regularly (External drive + cloud)
8. Don't plug in random USB drives

Why malware exists

Almost all modern malware is financially motivated. Old viruses were sometimes pranks or research projects. Today's malware is run by criminal organizations selling stolen credentials, holding files for ransom, or stealing crypto. The economics drive the volume.