Malicious Software

Malicious software is the general name for programs that perform malicious actions on your PC.  This can include stealing your personal information, locking your PC until you pay a ransom, using your PC to send spam, or downloading other malicious software.

Most software that we classify as malware falls into one of the following categories:

• Backdoor trojan: A type of trojan that gives a malicious hacker access to and control of your PC. This means they may be able to tell your PC what to do or monitor what you do online. A bot is a type of backdoor trojan.

• Downloader: A type of trojan that downloads other malware onto your PC. The downloader needs to connect to the Internet to download the files.

• Dropper: A type of trojan that installs other malware files onto your PC. The other malware is included within the trojan file. This is different to a downloader, which needs to connect to the Internet to download other files.

• Exploit: A piece of code that uses software vulnerabilities to access information on your PC or install malware. For more information, see our page on exploits.

• Hacktool: A type of tool that can be used to allow and maintain unauthorized access to your PC.

• Macro virus: A type of virus that spreads through infected documents such as Microsoft Word or Excel documents. The virus is run when you open an infected document.

• Obfuscator: A type of malware that hides its code and purpose to make it more difficult for security software to detect or remove it.

• Password stealer: A type of malware that is used steal your personal information, such as user names and passwords. It often works along with a keylogger that collects and sends information about what keys you press and websites you visit to a malicious hacker.

• Ransomware: A type of malware that can stop you from using your PC, or encrypt your files so you can’t use them. You may be warned that you need to pay money, complete surveys, or perform other actions before you can use your PC again. For more information, see our ransomware page.

• Rogue security software: Software that pretends to be an antivirus program but doesn't actually provide any security. This type of software usually gives you a lot of alerts about threats on your PC that don't exist. It also tries to convince you to pay for its services. Our rogue security software page has more information.

• Trojan: A type of malware. A trojan is a program that tries to look innocent, but is actually a malicious application. Unlike a virus or a worm, a trojan doesn't spread by itself. Instead they try to look innocent to convince you to download and install them. Once installed, a trojan can steal your personal information, download more malware, or give a malicious hacker access to your PC.

• Trojan clicker: A type of trojan that can use your PC to "click" on websites or applications. They are usually used to make money for a malicious hacker by clicking on online advertisements and making it look like the website gets more traffic than it does. They can also be used to skew online polls, install programs on your PC, or make unwanted software appear more popular than it is.

• TrojanSpy: A program that collects your personal information, such as your browsing history, and uses it without adequate consent.

• Virtool: A detection that is used mostly for malware components, or tools used for malware-related actions, such as rootkits.

• Worm: A type of malware that spreads to other PCs. Worms may spread using one or more of the following methods: email programs, instant messaging programs, file-sharing programs, social networking sites, network shares, removable drives with Autorun enabled, and software vulnerabilities.