Like some terms in information security and incident response, threat intelligence is a bit nebulous. Various organizations such as the government and academics produce information and data that is often touted as threat intelligence. Various commercial providers also have information available, either through free or paid subscriptions, that is touted as threat intelligence. This often results in difficulty when determining what threat intelligence is and what, simply, data or information is.

A good starting point to determine what comprises threat intelligence is to utilize a definition. Here is the Gartner research company's definition of threat intelligence:

When examining this definition, there are several key elements that need to be present for data or information to be considered threat intelligence:

• Evidence-based: This chapter will examine how evidence obtained through other processes, such as malware analysis, produces threat intelligence. For any intelligence product to be useful, it must first be obtained through proper evidence collection methods. In this way, analysts that rely on it can be sure of its validity.
• Utility: For threat intelligence to have a positive impact on a security incident's outcome or an organization's security posture, it has to have some utility. The intelligence must provide clarity, in terms of context and data, about specific behaviors or methods to determine whether an analyst is evaluating an incident against other incidents of a similar nature.
• Actionable: The key element that separates data or information from threat intelligence is action. Intelligence should drive action, whether that is a specific sequence of events or a specific focus area of an incident, or whether or not a specific security control is implemented in the face of intelligence about what cyber threats the organization is most likely to face.

To see how this plays together, imagine a scenario where an incident response team at a healthcare institution is attempting to ascertain what types of attacks are most likely to occur against their infrastructure. Vague data about cybercriminals wanting to steal data is not useful. There is no specific context or information in that dataset and the end result is that the organization cannot put that information into action.

On the other hand, say that the incident response team leverages a third-party threat intelligence provider. This third party outlines a specific criminal group by name. The provider also indicates that these groups are currently utilizing PDF files sent via email to hospital employees. The PDF files contain a remote access Trojan that is controlled from C2 servers, which are spread out in Europe. The third party also provides the team with MD5 file hashes of malware, the IP and domain addresses of the C2 servers, and, finally, the filenames most associated with the PDF document.

With this information, the incident response team can align their security controls to prevent PDF attachments from opening in emails. They can also utilize tools to search their infrastructure to determine whether an infection has already occurred. Finally, they may be able to configure their event management solution in order to alert the team if any host within the network attempts to communicate with the C2 server.

The major difference between these two scenarios is that the latter scenario drives actions within the organization. In the first scenario, the information was so vague and useless that the organization was left no better off. In the second scenario, the team could execute specific actions to either prevent an adverse condition or be better prepared to respond to one.

Threat intelligence is a response to the increased complexity and technical skill of cyber threat actors. The focus of threat intelligence is on the following threat actor groups:

• Cybercriminals: Organized and technically skilled, cybercriminals have been responsible for a variety of financial crimes against banking, retail, and other organizations. The motive for these groups is purely mercenary and their ultimate goal is to acquire data that can be monetized. For example, attacks against retailers such as Home Depot and Target involved the theft of credit card data with the intent of selling numbers on the dark web or other black markets.
• Hacktivism: Groups such as Anonymous and the Idlib Martyrs' Brigade are hacker groups that take on large businesses, governments, and even religious institutions to further a political cause. Penetrating networks to obtain confidential data for disclosure or conducting denial-of-service attacks is done as part of an overall political versus monetary objective.
• Cyber espionage: Nation states such as the United States, Russia, China, Iran, and North Korea continually engage in espionage activities involving penetrating networks and obtaining intelligence. One of the most well-known cyberattacks, the Stuxnet virus, was reportedly perpetrated by the United States and Israel.

Another key element to understanding threat intelligence is the concept of Advanced Persistent Threat (APT). The term APT has been around for approximately a decade, and it is used to describe a cyber threat actor whose capability and motivation go far beyond that of a cybercriminal or cyber vandal. APT groups often target organizations for an intended purpose with a clear objective in mind and over a long period of time. As the term APT describes, these groups have the following characteristics:

• Advanced: APT threat actors have advanced skills. These skills often involve intelligence gathering skills that exceed what can be obtained through open source methods. This includes such sources as Imagery Intelligence (IMINT), which includes pictures available through sites such as Google Earth. Signals Intelligence (SIGINT) is intelligence gathered through the compromise of voice and data communications that use telephone infrastructure, cellular data, or radio signals. Finally, APT groups have the ability to leverage Human Intelligence (HUMINT) or gather intelligence from interacting with human sources. Further, these groups can not only utilize advanced network penetration tools, but they are also adept at finding zero-day vulnerabilities and crafting custom malware and exploits that specifically target these vulnerabilities.
• Persistent: APT threat actors are focused on a clearly defined objective and will often forgo other opportunities to get closer to achieving their objective. APT threat actors will often go months or even years to achieve an objective through the intelligent leveraging of vulnerabilities and continuing a pace that allows them to bypass detection mechanisms. One of the key differentiators between APT threat actors and others is the intention to stay within the target network for a long period of time. Whereas a cybercriminal group will stay long enough to download a database full of credit card numbers, an APT group will maintain access within a network for as long as possible.
• Threat: To organizations that face APT groups, they are most definitely a threat. APT threat actors conduct their attacks with a specific objective and have the necessary infrastructure and skillset to attack targets such as large corporations, the military, and government organizations.

Threat intelligence is a wide field of study with many elements that are tied together. In the end, threat intelligence should drive action within an organization. What that action may be is often decided after careful evaluation of the threat intelligence. This involves understanding the type of threat intelligence being reviewed and what advantage each of those types provides the organization.