Prioritization

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Time
4 hours 42 minutes
Difficulty
Intermediate
CEU/CPE
5
Video Transcription
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>> Welcome to Lesson 1.4 of Threat Hunting Fundamentals.
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In the last lesson, we dove into
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David Bianco's Pyramid of Pain and our take on it.
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We laid out reasons why
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our approach to detection is focused
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on knowledge of adversarial behaviors
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as described in attacks,
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tactics, techniques, and procedures.
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In this lesson, we'll talk about how to
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prioritize your hunting development efforts to
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focus your limited resources on things that have the
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most potential to provide
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lasting benefit for your situation.
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To start, it's wise to ensure that you and
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your organization have a clear understanding
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of purpose for your hunting activities.
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Having a clear and shared purpose helps to align
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your team and your stakeholders to strategic priorities.
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It enables you to optimize your limited resources,
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identify the parts of
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your environment and malicious behaviors to focus on,
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and also helps you measure your progress as you go.
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We're all dealing with limited resources,
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time, money, bandwidth, storage, processing.
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Given those limited resources,
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it makes sense to think through the technologies you're
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using and the scenarios you're concerned about.
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Let's prioritize the techniques that are relevant
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to our business and the technologies we use.
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In time, things will change and we should periodically
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check back in on our filtering decisions
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and update them if needed.
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Adversaries are constantly seeking
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new ways to accomplish their goals and evade detection.
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We need to be sure we're keeping up.
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Our own systems are also changing frequently.
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As functionality, software,
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and devices are added and updated,
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we need to make sure we're including
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the associated analytics and data collection plans.
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Keep in mind that community knowledge, best practices,
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and ideas are also
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frequently being updated in response to
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adversary evolution in technology change
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and new discoveries of
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existing adversaries and technology.
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We need to stay aware of
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those changes and keep our filtering
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up-to-date to ensure we
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continue to include relevant analytics and monitoring.
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In many cases, it will be appropriate to
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filter based on technology.
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Which technologies are in your environment?
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For example, if you don't use industrial control systems,
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then the techniques associated with
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ICS are not likely to be relevant for you,
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and you can filter them out along with
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their hypotheses and analytics
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and data collection requirements.
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Just keep in mind that you might have
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more technologies in your environment
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than you first think.
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For example, even if you have
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a relatively small network with Windows hosts,
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the routers, switches, servers,
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and firewalls might be running Linux or Cisco.
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Your team might bring in their own mobile devices or
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laptops which might not run windows.
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Are there IoT devices in your environment?
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Do you have capabilities hosted in the Cloud?
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Be sure to think it through.
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Note the versions and
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configurations of your software as well,
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since those can influence
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which techniques or sub techniques apply.
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As you progress through this process,
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you might uncover technologies in
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your environment that you hadn't realized were there.
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Which means you'll want to revisit
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this prioritization to ensure those are included.
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In addition to considering
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the technologies your business uses,
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think about what it takes for your business to succeed.
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What kinds of failure scenarios could disrupt it?
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With a clear understanding of business objectives and
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how those map to cyber systems and functions,
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you can further prioritize your hunt.
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Analyze which systems store or process
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sensitive information and which
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accounts have access to it.
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Those could be likely targets of an adversary seeking to
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steal intellectual property or
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holds your information for ransom.
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What would the impact be if an adversary
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modified that information without
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your knowledge or shared it with a competitor?
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Are there any single points of failure for your business?
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Which systems or functions would have
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a negative impact on
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your business if they were disrupted?
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How would an adversary cause
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those failure scenarios to occur through cyber actions?
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Which systems would they need access to?
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Which account accesses would be useful
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or necessary for the adversary to have?
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What are the paths from the Internet or from
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an insider through your environment
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that would enable an adversary to achieve those goals?
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Which attack techniques would an adversary be
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most likely to employ along those attack paths?
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Finally, what does
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the cyber threat intelligence indicate are
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the top threats to your business or business sector?
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Are there certain techniques more commonly used against
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your type of business or by
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adversaries known to be interested in your business?
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Answering these questions can
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help you prioritize techniques.
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Finally, consider how you
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might filter based on malicious behavior.
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Conduct a SOK assessment.
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Do some purple teaming,
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conduct evaluations of your current defensive posture
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relative to attack techniques,
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and get an understanding of your gaps.
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If you have defensive gaps for some of the techniques
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identified based on your technologies
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and business needs,
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those are great candidates for prioritization.
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Within those techniques, which are
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good candidates for detection in your environment?
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Are the techniques likely to be detectable?
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Will you be able to distinguish malicious use of
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those techniques relative to
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the benign background activity
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that's going on in your environment?
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Keep in mind that some analytics are excellent
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for getting the initial detection of malicious activity.
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But you might need others to flush out the context of
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that activity and help distinguish
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malicious from benign actions,
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or to one cover the full scope
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of the adversaries campaign.
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What other mitigations or detections in
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your current defensive posture could help to
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complement your efforts to
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fill the gaps you've identified?
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Are there any techniques for
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which the broader community has
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already developed good mitigation or detection solutions?
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Be sure to leverage those as much as possible.
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In addition to using
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CTI about your business specifically,
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take note of commonly used techniques across the board.
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They could be relevant to your environment as well.
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After answering the questions in the previous slides,
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you'll be able to develop
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a clear and shared purpose
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for your current hunting activities.
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For example, you might have
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decided to focus on hunting for evidence of
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lateral movement in your engineering department
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or spearfishing indicative of APT3.
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These example purpose statements illustrate how you might
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narrow your current focus down to a subset of behaviors,
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threat actors, and parts of your environment.
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Let's dive a little deeper on the example of hunting for
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persistence consistent with APT3.
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Let's say the cyber threat intelligence indicates
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that APT3 is targeting our business sector.
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We could break that down into
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smaller areas of focus by filtering
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the APT3 persistence techniques documented in attack to
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those applicable to Windows
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since that's the platform our company uses.
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Now we're looking at eight techniques or sub-techniques.
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When we consider our business needs,
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we might decide that our top priority for
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this hunt will be
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the systems used by our product developers,
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which contains sensitive information that could
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give our competitors a head-start
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if they had access to it.
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We can then assess our current defensive posture
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relative to those eight techniques across those systems.
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Checking which mitigations are already in place,
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the data we're currently collecting,
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and how that's being analyzed already.
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We might find that the biggest defensive gap is
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currently in detecting the scheduled task sub-technique.
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By starting with a strategic purpose
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and applying our knowledge of our CTI,
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the technologies in our environment, our business needs,
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and our current defensive posture,
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we've narrowed down our focus to one sub-technique.
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Of the hundreds of techniques and
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sub-techniques documented in attack matrices,
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how do you prioritize your resources?
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The first step we recommend is to
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identify the technologies present in
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your environment so you can narrow down the set of
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attack matrices and platforms
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that are relevant to your situation.
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Second, we found that is very
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valuable to think clearly about your business,
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the failure scenarios or
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disruptions you're concerned about,
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and how those are dependent on cyber.
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That mapping of impacts to cyber can help identify
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the cyber systems and functions that
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represent your crown jewels.
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Once identified, you can determine
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attack paths through your environment that
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could create this negative impacts and discover
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the attack techniques and adversary is likely to
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implement to navigate those paths.
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You might find that there are
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certain techniques associated with a lot of risk to
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your business and are worth
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spending resources defending against.
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Third, you likely already have mitigations and
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detections in place that are
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effective against some of these techniques.
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A SOK assessment can help you understand
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your current defensive posture and identify gaps to fill.
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Attack evals can provide information on
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how different products map to attack techniques.
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Adversary emulation and purple teaming can test
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your current defenses and
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further illuminate the gaps that need filling.
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Once you've narrowed down the list of
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techniques to those that
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are relevant to your environment,
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impactful to your business,
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and are currently poorly defended,
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you might find that you have
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a more manageable list of techniques to focus on.
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However, as noted in previous med courses,
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not all attack techniques are
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equally amenable to detection.
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Look for techniques that are
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detectable in your environment,
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those that are likely to have few false alarms,
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and for which you might be able to
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collect the right data to detect.
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Finally, you might want to prioritize
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techniques that are used by multiple groups of interest.
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If you can effectively
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defend against a commonly used technique,
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you're more likely to get
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a better return on your investment of resources.
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