These individuals or groups commit cybercrimes mostly for financial gain. Common crimes that are committed by cybercriminals include ransomware attacks and phishing scams that trick people into making money transfers or divulging credit card information, login credentials, intellectual property or other private or sensitive information. 

Nation states and governments frequently fund threat actors with the goal of stealing sensitive data, gathering confidential information or disrupting another government’s critical infrastructure. These malicious activities often include espionage or cyberwarfare and tend to be highly funded, making the threats complex and challenging to detect. 

These threat actors use hacking techniques to promote political or social agendas, such as spreading free speech or uncovering human rights violations. Hacktivists believe that they are affecting positive social change and feel justified in targeting individuals, organizations or government agencies to expose secrets or other sensitive information. A well-known example of a hacktivist group is Anonymous, an international hacking collective that claims to advocate for freedom of speech on the internet.

Thrill seekers are just what they sound like: they attack computer and information systems primarily for fun. Some want to see how much sensitive information or data they can steal; others want to use hacking to better understand how networks and computer systems work. One class of thrill seekers, called script kiddies, lack advanced technical skills, but use pre-existing tools and techniques to attack vulnerable systems, primarily for amusement or personal satisfaction. Though they don't always seek to cause harm, thrill seekers can still cause unintended damage by interfering with a network's cybersecurity and opening the door to future cyberattacks. 

Unlike most other actor types, insider threat actors do not always have malicious intent. Some hurt their companies through human error, such as by unwittingly installing malware or losing a company-issued device that a cybercriminal finds and uses to access the network. But malicious insiders do exist. For example, the disgruntled employee who abuses access privileges to steal data for monetary gain or inflicts damage to data or applications in retaliation for being passed over for promotion.

Cyberterrorists start politically or ideologically motivated cyberattacks that threaten or result in violence. Some cyberterrorists are nation-state actors; others are actors on their own or on behalf of a nongovernment group. 

Malware is malicious software that damages or disables computers. Malware is often spread through email attachments, infected websites or compromised software and can help threat actors steal data, take over computer systems and attack other computers. Types of malware include viruses, worms and Trojan horse viruses, which download onto computers disguised as legitimate programs. 

Ransomware is a type of malware that locks up the victim's data or device and threatens to keep it locked up—or worse—unless the victim pays a ransom to the attacker. Today most ransomware attacks are double-extortion attacks that also threaten to steal the victim's data and sell it or leak it online. According to the IBM X-Force® Threat Intelligence Index, ransomware attacks represent 20 percent of all malware attacks.

Big game hunting (BGH) attacks are massive and coordinated ransomware campaigns that target large organizations, including governments, major enterprises, and critical infrastructure providers that have lots to lose from an outage and will be more likely to pay a large ransom.

Phishing attacks use email, text messages, voice messages or fake websites to deceive users into sharing sensitive data, downloading malware or exposing themselves to cybercrime. Types of phishing include:

• Spear phishing, a phishing attack that targets a specific individual or group of individuals with messages that appear to come from legitimate senders who have a relationship to the target.

• Business email compromise, a spear phishing attack that sends the victim a fraudulent email from a co-workers or colleague's impersonated or hijacked email account.
  
  
• Whale phishing, a spear phishing attack aimed specifically at high-level executives or corporate officers.

Phishing is one form of social engineering, a class of attacks and tactics that exploit feelings of fear or urgency to manipulate people into making other mistakes that compromise their personal or organizational assets or security. Social engineering can be as simple as leaving a malware-infected USB drive where someone will find it (because "hey, free USB drive!"), or as complex as spending months cultivating a long-distance romantic relationship with the victim in order to bilk them out of plane fare so they can "finally meet".

Because social engineering exploits human weakness rather than technical vulnerabilities, it is sometimes called "human hacking".

This type of cyberattack works by flooding a network or server with traffic, making it unavailable to users. A distributed denial-of-service (DDoS) attack marshalls a distributed network of computers to send the malicious traffic, creating an attack that can overwhelm the target faster and be more difficult to detect, prevent or mitigate.

Advanced persistent threats (APTs) are sophisticated cyberattacks that span months or years rather than hours or days. APTs enable threat actors to operate undetected in the victim's network, infiltrating computer systems, conducting espionage and reconnaissance, escalating privileges and permissions (called lateral movement) and stealing sensitive data. Because they can be incredibly difficult to detect and relatively expensive to run, APTs are typically started by nation-state actors or other well-funded threat actors.

A backdoor attack exploits an opening in an operating system, application or computer system that is not protected by an organization's cybersecurity measures. Sometimes, the backdoor is created by the software developer or hardware manufacturer to enable upgrades, bug fixes or (ironically) security patches; other times, threat actors create backdoors of their own using malware or by hacking the system. Backdoors allow threat actors to enter and exit computer systems undetected.