Cyber threat intelligence
It is not the goal of this book to deep dive into complex issues surrounding the different definitions of intelligence and the multiple aspects of intelligence theory. This chapter is meant to be an introduction to the intelligence process so that you understand what cyber threat intelligence (CTI) is and how it is done, before we cover CTI-driven and data-driven threat hunting. If you think you are well-versed in this matter, you can proceed straight to the next chapter.
If we want to discuss the roots of intelligence discipline, we could probably go back as far as the 19th century, when the first military intelligence departments were founded. We could even argue that the practice of intelligence is as old as warfare itself, and that the history of humanity is full of espionage stories as a result of needing to have the upper hand over the enemy.
It has been stated over and over that in order to have a military advantage, we must be capable not only of understanding ourselves, but also the enemy: how do they think? How many resources do they have? What forces do they have? What is their ultimate goal?
This military need, especially during the two World Wars, led to the growth and evolution of the intelligence field as we know it. Several books and papers have been written about the craft of intelligence, and I sincerely encourage anyone interested in the matter to visit the Intelligence Literature section of the CIA Library (https://www.cia.gov/library/intelligence-literature) where you can find several interesting lectures on the subject.
The definition of intelligence has been under academic discussion among people better-versed in the matter than me for more than two decades. Unfortunately, there is no consensus over the definition of the intelligence practice. In fact, there are those who defend the craft of intelligence as something that can be described, but not defined. In this book, we are going to detach ourselves from such pessimistic views and offer the definition proposed by Alan Breakspear in his paper A New Definition of Intelligence (2012) as a reference:
Based on this, we are going to define CTI as a cybersecurity discipline that attempts to be a proactive measure of computer and network security, which nourishes itself from the traditional intelligence theory.
CTI focuses on data collection and information analysis so that we can gain a better understanding of the threats facing an organization. This helps us protect its assets. The objective of any CTI analyst is to produce and deliver relevant, accurate, and timely curated information – that is, intelligence – so that the recipient organization can learn how to protect itself from a potential threat.
The sum of related data generates information that, through analysis, is transformed into intelligence. However, as we stated previously, intelligence only has value if it is relevant, accurate, and, most importantly, if it is delivered on time. The purpose of intelligence is to serve those responsible for making decisions so they can do so in an informed way. There is no use for this if it is not delivered before the decision must be made.
This means that when we talk about intelligence, we are not only referring to the product itself, but also to all the processes that make the product possible. We will cover this in great detail in this chapter.
Finally, we can classify intelligence according to the time that's been dedicated to studying a specific subject, either by distinguishing between long-term and short-term intelligence, or according to its form; that is, strategic, tactical, or operational intelligence. In this case, the intelligence that's delivered will vary, depending on which recipients are going to receive it.
Strategic level
Strategic intelligence informs the top decision makers – usually called the C-suite: CEO, CFO, COO, CIO, CSO, CISO – and any other chief executive to whom the information could be relevant. The intelligence that's delivered at this level must help the decision makers understand the threat they are up against. The decision makers should get a proper sense of what the main threat capabilities and motivations are (disruption, theft of proprietary information, financial gain, and so on), their probability of being a target, and the possible consequences of this.
Operational level
Operational intelligence is given to those making day-to-day decisions; that is, those who are in charge of defining priorities and allocating resources. To complete these tasks more efficiently, the intelligence team should provide them with information regarding which groups may target the organization and which ones have been the most recently active.
The deliverable might include CVEs and information regarding the tactic used by, as well as the techniques of, the possible threat. For example, this could be used to assess the urgency to patch certain systems or to add new security layers that will hinder access to them, among other things.
Tactical level
Tactical intelligence should be delivered to those in need of instantaneous information. The recipients should have a complete understanding of what adversary behaviors they should be paying attention to in order to identify the threats that could target the organization.
In this case, the deliverable may include IP addresses, domains and URLs, hashes, registry keys, email artifacts, and more. For example, these could be used to provide context to an alert and evaluate if it is worth involving the incident response (IR) team.
So far, we have defined the concepts surrounding intelligence, CTI, and intelligence levels, but what do we understand by the term threat in the cyber realm?
We define a threat as any circumstance or event that has the potential to exploit vulnerabilities and negatively impact operations, assets (including information and information systems), individuals, and other organizations or societies of an entity.
We could say that the main areas of interest for cyber threat intelligence are cybercrime, cyberterrorism, hacktivism, and cyberespionage. All of these can be roughly defined as organized groups that use technology to infiltrate public and private organizations and governments to steal proprietary information or cause damage to their assets. However, this doesn't mean that other types of threats, such as criminals or insiders, are outside the scope of interest.
Sometimes, the terms threat actor and advanced persistent threat (APT) are used interchangeably, but the truth is that although we can say that every APT is a threat actor, not every threat actor is advanced or persistent. What distinguishes an APT from a threat actor is their high level of operational security (OPSEC), combined with a low detection rate and a high level of success. Keep in mind that this might not apply perfectly to all APT groups. For example, there are some groups that feed on the propaganda from the attack, so they put less effort into not being identified.
In order to generate valuable intelligence, it is important to work with clear and defined concepts so that you can structure the data and generate information. It is not mandatory to choose an existing terminology, but the MITRE Corporation has developed the Structured Threat Information Expression (STIX) (https://oasis-open.github.io/cti-documentation/) in order to facilitate the standardization and sharing of threat intelligence.
So, if we follow the STIX definition (https://stixproject.github.io/data-model/), threat actors are "actual individuals, groups, or organizations believed to be operating with malicious intent." Any threat actor can be defined by any of the following:
- Its type (https://stixproject.github.io/data-model/1.1/stixVocabs/ThreatActorTypeVocab-1.0/)
- Its motivations (https://stixproject.github.io/data-model/1.1/stixVocabs/MotivationVocab-1.1/)
- Its sophistication level (https://stixproject.github.io/data-model/1.1/stixVocabs/ThreatActorSophisticationVocab-1.0/)
- Its intended effect (https://stixproject.github.io/data-model/1.1/stixVocabs/IntendedEffectVocab-1.0/)
- The campaigns it was involved in
- Its Tactics, Techniques, and Procedures (TTPs): https://stixproject.github.io/data-model/1.2/ttp/TTPType/)
In summary, cyber threat intelligence is a tool that should be used to gain better insight into a threat actor's interests and capabilities. It should be used to inform all the teams involved in securing and directing the organization.
To generate good intelligence, it is necessary to define the right set of requirements for understanding the needs of the organization. Once this first step has been accomplished, we can prioritize the threats the team should be focusing on and start monitoring those threat actors that might have the organization among its desired targets. Avoiding the collection of unnecessary data will help us allocate more time and resources, as well as set our primary focus on the threats that are more imminent to the organization.
As Katie Nickels stated in her talk The Cycle of Cyber Threat Intelligence (2019, https://www.youtube.com/watch?v=J7e74QLVxCk), the CTI team is going to be influenced by where they've been placed, so having them at a central position in the structure of the organization will help the team actually support different functions. This can be visualized as follows:
Figure 1.1 – CTI team center role
We will now have a look at the intelligence cycle.
