Malware: Viruses, Worms, Trojans, Spyware, Adware and Ransomware

Hello students, welcome to Kwickprep. You download a free game, and next morning all your photos are locked. What happened? Your device caught malware. Today we will see how six types of malware spread and what they do. We will also learn the signs of infection, how to remove malware and how to prevent it.

First, the word. Malware is short for malicious software, which means software made to cause harm. It can damage files, steal data or spy on you. It can also take control of your device or demand money. Malware usually needs a way in, such as a download, a link or a pen drive.

Here are the six types we will study. A virus attaches itself to a file. A worm copies itself across a network on its own. A trojan hides inside software that looks useful. Spyware secretly watches what you do. Adware floods you with advertisements. Ransomware locks your files and demands money.

Watch how a virus spreads. First, a virus attaches itself to a normal file, such as a program or document. The infected file is shared, for example on a pen drive. Nothing happens until someone opens or runs the file. When they do, the virus runs and copies itself into other files. It may also corrupt or delete data.

A worm is different, because it does not need a person to open anything. First, a worm reaches one computer on a network. It looks for other computers with a security weakness. It sends copies of itself to each of them automatically. Each new copy repeats the same steps. Soon the network slows down because of all the copies.

Exams often ask the difference between a virus and a worm. A virus needs a host file, while a worm is a complete program on its own. A virus spreads when a user opens the file, while a worm spreads by itself. A virus mainly damages files, while a worm mainly eats up network speed and storage.

A trojan is named after the wooden horse in an old Greek story, which hid soldiers inside. First, you see a free app, a cracked game or a fake update. It looks useful, so you install it yourself. The app may even work normally. Hidden inside, it opens a back door, which is a secret way for the attacker to control your device. A trojan does not copy itself like a virus.

Spyware and adware often come bundled with free software. Spyware secretly collects information, such as the websites you visit. A keylogger is a kind of spyware that records every key you press, including passwords. Adware shows unwanted advertisements and pop ups again and again. Adware can also change your browser's home page and slow down your device.

Ransomware is one of the most damaging types. First, a fake email with an attachment arrives, perhaps pretending to be a bill. The user opens the attachment. The ransomware encrypts the files, which means it scrambles them so they cannot be opened. A message then demands payment, often in cryptocurrency. Paying gives no guarantee that the files will come back.

How do you know a device may be infected? The device becomes very slow, or the battery and data drain fast. Strange pop ups and ads appear, even when no browser is open. Unknown apps appear, or your home page changes by itself. Files go missing or cannot be opened. Your friends receive messages from you that you never sent.

Pause and predict. Which malware is most likely? Your files suddenly have strange names and a payment note appears, so it is ransomware. Ads keep popping up after installing a free wallpaper app, so it is adware. A friend's bank password was stolen after she typed it, so a keylogger, which is spyware. The whole school network slows down without anyone opening files, so it is a worm.

If you think a device is infected, act calmly and in order. First, disconnect from the internet, so the malware cannot spread or send data. Run a full scan with trusted antivirus software, which finds and removes malware. Uninstall unknown apps and remove strange browser extensions. Change your passwords from a different, clean device. If nothing works, restore files from a backup or reset the device.

Ransomware needs extra care. Do not pay the ransom, because criminals may never unlock your files. Unplug any backup drives, so they are not encrypted too. Report the attack on India's national cyber crime portal, cybercrime dot gov dot in. Organisations should also report it to cert in, the national team that handles cyber security incidents.

Prevention is always better than cure. Keep your operating system and apps updated, because updates fix security weaknesses. Keep antivirus and the firewall switched on, where a firewall is a guard that blocks unwanted network traffic. Download apps only from official app stores. Do not open unknown attachments or links, and scan pen drives before use. Keep regular backups, so ransomware cannot hold your files hostage.

Let us revise what we learned today. Malware is software made to cause harm. A virus needs a host file, a worm spreads by itself, and a trojan pretends to be useful. Spyware watches you, adware floods you with ads, and ransomware locks files for money. Slowness, pop ups and missing files are signs of infection. Disconnect and scan to remove it, and prevent it with updates, antivirus and backups.