Internet, Networking, & Security Antivirus The 4 Scariest Types of Malware Share Pin Email Print ribkhan/iStock Antivirus Browsers Cloud Services Error Messages Home Networking 5G Antivirus VPN Web Development Around the Web View More By Andy O'Donnell Writer Andy O'Donnell, MA, is a former freelance contributor to Lifewire and a senior security engineer who is active in internet and network security. our editorial process Andy O'Donnell Updated July 13, 2019 Malware, even the term itself sounds kind of scary, doesn't it? Malware is defined as software that is intended to damage or disable computers and computer systems. There are many flavors of malware, from run-of-the-mill computer viruses to sophisticated state-sponsored cyberweapons designed to carry out a very specific goal. Some types of malware can be more destructive and insidious than other forms. Rootkit Malware A Rootkit is a kind of software that is both stealthy and malicious. The goal of a rootkit is to establish administrator-level access (hence the "root" designation) for the hacker/operator, allowing for complete control over the compromised system. The other goal of the rootkit is to evade detection by antimalware so that control of the system can be maintained. Rootkits typically have the ability to hide their very existence and can be hard to detect. Detection and removal can be somewhat difficult to practically impossible, depending on the type of rootkit installed. Recovery can sometimes require the entire operating system to be wiped from the computer and reloaded from trusted media. Ransomware Ransomware is exactly what it sounds like, malware that infects a computer system, often encrypting the user's data, and then demanding money (via wire transfer or other means) for the key to unlocking (decrypt) the victim's data. If the money is not paid within the time frame established by the person running the ransomware scam, the criminals threaten to keep the key a secret forever, rendering the data on the computer useless. One of the most famous Ransomware programs is known as CryptoLocker. It is believed to have been used to extort as much as 3 million dollars ($US) from victims all over the world. Ransomware is an offshoot of Scareware which is another form of malware that attempts to extort money from victims through threats and deception. Some Ransomware is removable without resorting to paying the demands of the attackers. You may also want to read our article on Ransomware for much more details on this form of malware. Persistent Malware (Advanced Persistent Threat Malware) Some malware can be very difficult to get rid of, Just when you think your antivirus software has gotten rid of it, it seems to return. This type of malware is called Persistent Malware or Advanced Persistent Threat Malware. It typically infects a system with multiple malware programs and leaves pieces of itself behind that are not easily cleaned by virus scanners. Even after this malware is removed from a system, the configuration changes it makes to the web browser may redirect users back to malware sites where they may be reinfected, causing a vicious cycle of reinfection, even after removal had been seemingly successful. Other forms of persistent malware embed themselves in hard drive firmware which can't usually be seen by virus scanners and are also very difficult (and sometimes impossible) to remove. Firmware-Based Malware Probably the scariest of all forms of malware is the kind that is installed into hardware components such as hard drives, system bios, and other peripherals. Sometimes the only way to fix this kind of infection is to completely replace the infected hardware, an extremely costly endeavor, especially if the infection is widespread across multiple computers. Firmware-resident malware is also extremely difficult to detect because traditional virus scanners can't scan firmware for threats.