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<title>Best Practices in Threat Intelligence</title>
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<body class="book">
<div id="header">
<h1>Best Practices in Threat Intelligence</h1>
<div class="details">
<span id="author" class="author">MISP Project</span><br>
</div>
<div id="toc" class="toc">
<div id="toctitle">Table of Contents</div>
<ul class="sectlevel1">
<li><a href="#_introduction">Introduction</a></li>
<li><a href="#_best_practices">Best Practices</a>
<ul class="sectlevel2">
<li><a href="#_improving_analysis">Improving Analysis</a></li>
<li><a href="#_what_to_share_or_what_counts_as_valuable_information">What To Share or What Counts As Valuable Information?</a></li>
<li><a href="#_intelligence_tagging">Intelligence Tagging</a></li>
<li><a href="#_expressing_confidenceestimative_probability_in_an_analysis">Expressing confidence/estimative probability in an analysis</a></li>
<li><a href="#_how_to_track_and_keep_the_state_of_an_analysis">How to track and keep the state of an analysis</a></li>
<li><a href="#_how_to_classify_label_information">How to classify (label) information</a></li>
</ul>
</li>
<li><a href="#_authors_and_contributors">Authors and Contributors</a></li>
<li><a href="#_glossary">Glossary</a></li>
</ul>
</div>
</div>
<div id="content">
<div class="sect1">
<h2 id="_introduction">Introduction</h2>
<div class="sectionbody">
<div class="paragraph">
<p>The aim of this book is to compile the best practices in threat intelligence analysis.</p>
</div>
<div class="paragraph">
<p>Whilst this book can be used as a general guide, it is based on the open source threat intelligence platform called <a href="https://www.misp-project.org/">MISP</a> to give the reader the most practical and real-world experience.</p>
</div>
<div class="paragraph">
<p>The best practices described herein are from Information Sharing communities (<a href="#ISAC">ISAC</a> or CSIRT) which are regularly using MISP to support their work and sharing practices.</p>
</div>
</div>
</div>
<div class="sect1">
<h2 id="_best_practices">Best Practices</h2>
<div class="sectionbody">
<div class="sect2">
<h3 id="_improving_analysis">Improving Analysis</h3>
<div class="admonitionblock note">
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Improvement of the analysis process can range from a simple notification of a false-positive or the correction of a typographic error, all the way up to a complete competitive or counter analysis of the original analysis.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>A common difficulty in threat intelligence is to improve existing analyses and especially how to do it efficiently.
One of the main questions to ask is:</p>
</div>
<div class="paragraph">
<p><strong>"What will be the target audience of the improved analysis and the objective thereof?</strong>"</p>
</div>
<div class="paragraph">
<p>The following three answers could come to mind.</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>Informing the original analyst/author (e.g. a security vendor or a CSIRT) about a specific mistake or error which needs to be corrected.</p>
</li>
<li>
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<p>Improving an existing analysis by performing a complementary analysis or review which will be shared to and used by another group (e.g. a specific constituent, or a team within your organisation or a member of an ISAC, etc).</p>
</li>
<li>
<p>The end-consumer will be an automaton.</p>
</li>
</ol>
</div>
<div class="paragraph">
<p>In the <strong>1st</strong> case, <a href="#MISP">MISP</a> includes a mechanism to propose changes to the original creator, a mechanism MISP refers to as proposals. By using proposals, you can propose a change to the value or the context of an attribute (such as a typographic error in an IP address, missing contextual information, type of the information, the category or the removal of an IDS flag). The proposal will be sent back to the original author who can decide to accept or discard it.</p>
</div>
<div class="paragraph">
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<p>The advantages of using the proposal system include the lack of a need to create a new event as well as the process itself being very simple and fast. However, it assumes that the party providing the improvements is willing to lose control over the proposed data. This is pretty efficient for small changes but for more comprehensive changes, especially those that include non-attribute information such as galaxy clusters or objects, the event extension is more appropriate.</p>
</div>
<div class="paragraph">
<p>Apart from being more suitable for more comprehensive changes, the <strong>2nd</strong> scenario is also a great fit for the extended event functionality, allowing users wanting to provide additional information or an alternate view-point with the opportunity of creating a self-contained event (which can have its own custom distribution rules) that references the original analysis. This information can be shared back to the original author or kept within a limited distribution scope such as a specific sector, a trust group or as internal information for the organisation providing the additional information.</p>
</div>
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For more information about the extended event functionality in MISP, the blog post <strong><a href="http://www.misp-project.org/2018/04/19/Extended-Events-Feature.html">Introducing The New Extended Events Feature in MISP</a></strong> includes a lot of details.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>In the <strong>3rd</strong> scenario your use-case might be highly automated, e.g. scripted processing of events and attributes via <a href="https://github.com/MISP/PyMISP">PyMISP</a> and the end-consumer is mainly another automated process, e.g. Intrusion Detection System, 3rd part visualization tool etc.
This, for automagic reasons, becomes exponentially unreliable.
What is primal in this case is to fully understand what the <a href="#IDS">IDS</a> flag in MISP does and how it impacts attributes.
Further on, it is even more important to fully understand the entire tool-chain, cradle-to-grave style.
Where does the data come from (cradle) where does it go to (grave) and what processes "touch" the data as it flows through, small diagrams can help tremendously to visualize the actual data-flow.
Those diagrams will mostly be of use once unexpected results occur, or other errors appear somewhere in the chain.</p>
</div>
<div style="page-break-after: always;"></div>
</div>
<div class="sect2">
<h3 id="_what_to_share_or_what_counts_as_valuable_information">What To Share or What Counts As Valuable Information?</h3>
<div class="admonitionblock note">
<table>
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<td class="icon">
<i class="fa icon-note" title="Note"></i>
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<td class="content">
Valuable information is a moving concept and depends highly on the goal of the users sharing and/or using the information. A valuable information can also evolve following the capabilities of an organisation.
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Contribution comes in various shapes and sizes.</p>
</div>
<div class="paragraph">
<p>Information which is often distributed within sharing communities are the following:</p>
</div>
<div class="ulist">
<ul>
<li>
<p>Analysis report of a specific threat (such as security vendor report, blog post) which can be Open Source intelligence or come as limited distribution</p>
</li>
<li>
<p>Enhanced analysis of an existing report (such as data qualification, competitive or counter analysis)</p>
</li>
<li>
<p>A post-mortem analysis of an incident</p>
</li>
<li>
<p>Additional information about existing or known threats (such as adversary techniques, new malware samples or complementary discoveries)</p>
</li>
<li>
<p>False-positive or false-negative reporting</p>
</li>
<li>
<p>Asking for contribution or support from the community (such as "have you seen this threat?" or "do you have more samples?" as described in <a href="https://www.misp-project.org/taxonomies.html#_collaborative_intelligence">collaborative intelligence</a> taxonomy)</p>
</li>
</ul>
</div>
<div class="admonitionblock tip">
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<td class="icon">
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<td class="content">
By having a look at <a href="https://www.misp-project.org/objects.html">the object templates</a> or the <a href="https://www.misp-project.org/datamodels/#misp-core-format">MISP attribute types</a>, this can help you discover what is actively shared within other communities. If a type or an object template is not matching your data model, you can easily create new ones.
</td>
</tr>
</table>
</div>
<div class="admonitionblock tip">
<table>
<tr>
<td class="icon">
<i class="fa icon-tip" title="Tip"></i>
</td>
<td class="content">
When asking for the support of the community, using a specific taxonomy such as <a href="https://www.misp-project.org/taxonomies.html#_collaborative_intelligence">collaborative intelligence</a> to express your needs, will make your request more concise improving your feedback potential and improve automation.
</td>
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</table>
</div>
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<i class="fa icon-tip" title="Tip"></i>
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<td class="content">
MISP allows to extend an existing event without touching the original event. This feature can be used to enhance analysis without affecting the original ones and creating new distribution levels.
</td>
</tr>
</table>
</div>
<div style="page-break-after: always;"></div>
</div>
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<div class="sect2">
<h3 id="_intelligence_tagging">Intelligence Tagging</h3>
<div class="paragraph">
<p>There are several factors to successful and efficient intelligence sharing. Certainly, one major aspect is the quality of the indicators (or <a href="#observables">observable</a> depending on the definition you use),
stored as attributes within a MISP event itself.
However, it does not stop there. Even the most viable information gained by a shared event can render itself complete useless if not classified and tagged accordingly.
One feature which enables a uniformed classification is implemented in MISP as tags. Currently, there are two types of tags, which differ in the respective place they are set.</p>
</div>
<div class="olist arabic">
<ol class="arabic">
<li>
<p>You can add tags to an <strong>entire event</strong>. These <strong>tags should be valid for any individual attribute</strong>, thus indicator associated to this specific event.</p>
</li>
<li>
<p>For a more fine-grained specification all of these tags can also be placed at attribute level. This allows the user to put a more detailed and selective view on each attribute.</p>
</li>
</ol>
</div>
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Currently there is no programmatic way that prevents you from not following the 1st rule. Thus human garbage tagging in automation output potentially useless.
</td>
</tr>
</table>
</div>
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<table>
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In future releases there will also be tagging for MISP Objects. Which is, somehow, an intermediate solution for the two prior mentioned options.
</td>
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</table>
</div>
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<a href="#MISPObjects">MISP Objects</a> in its plain concept is a grouping of indicators within one event. These grouped indicators are somehow logically linked together. The specific relationship is described by the individual object type.
A simple <strong>file object</strong>, links for example a filename to its observed hash values (md5, sha1, sha256 and many more). This can further be enriched via misp-modules or other plug-ins.
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</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>A frequent use-case for placing additional tags on <a href="#Attribute">attribute</a> level would be to lower the confidence in certain attributes. If the event is classified with a high confidence tag, some indicators e.g. legit-but-compromised domains or popular filenames should be labeled with a lowered confidence class. There are several real world examples where this or similar attribute specific tagging has proven to be worthwhile.</p>
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</div>
<div class="paragraph">
<p>Most of the tags are organised in dedicated MISP Taxonomies. Those schema dictate how tags should look like and how they are to be applied in certain conditions.
There are many general details on this topic which can be read up on in the main <a href="https://github.com/MISP/misp-taxonomies">MISP Taxonomy GitHub repository</a>.
Currently, there are more than 60 different taxonomies available, each of them containing a number of different tags, which are steadily increasing and evolving.
There are a lot of advantages in having such a vast variety of tags, e.g. there is one tag for each known associated malware type.</p>
</div>
<div class="paragraph">
<p>However, this sheer amount of tags can lead to two main concerns, <strong>over-tagging</strong> and <strong>miss-tagging</strong>. Beginners can be overwhelmed with the large number of available tags, and might miss exactly the required taxonomy to properly label the to be shared data.
As a site administrator it is thus important to enable the taxonomies that are known to the users on the MISP instance, (or to remote organizations you might sync with).</p>
</div>
<div class="admonitionblock note">
<table>
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</td>
<td class="content">
In MISP making a Taxonomy available is a 2-step process. First you make the taxonomy available and then you can either decide to enable all the individual tags in the taxonomy or cherry-pick only the relevant ones for your use-case. (The Vocabulary for Event Recording and Incident Sharing (VERIS) has well over 1990 tags, and perhaps you are only interested in the sub-set <code>veris:action:error:variety</code>).
</td>
</tr>
</table>
</div>
<div class="paragraph">
<p>Over-tagging in most cases only leads to an overwhelming visual appearance. Miss-tagging, however, is a critical step into mis-usage of shared data.
The best and most devastating example would be the miss classification of an event. In dedicated and private sharing groups it is quite usual to share intelligence labeled as „for your company only“.
This data must not leave the boundaries of this virtual border of the recipients firm.</p>
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<p>To prevent this kind of mistake, the traffic light protocol (aka TLP) and its respective taxonomy can be used and thus complementing the mitigation in the note below.</p>
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One mitigation the scenario of mis-classified data, would be to use the <a href="#MISPwarninglists">MISP warninglists</a> (or <a href="#MISPnoticelists">MISP noticelists</a>) as a canary. Whilst not ideal and far from a defacto solution to catch all issues, it would be a good-enough-yet-coarse way of detection.
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<p>There are multiple solutions to solve the issue of missing additional information about the shared content.
One of them is the following list of tags which are deemed to be the minimal subset at the start of any event or the individual attributes.
sharing platform. The list below is in order of importance.</p>
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<p><strong><a href="https://github.com/MISP/misp-taxonomies/blob/master/tlp/machinetag.json">TLP-Tags</a></strong>: <a href="https://www.us-cert.gov/tlp">TLP</a> utilizes a simple four color schema for indicating how intelligence can be shared.</p>
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<p><strong><a href="https://github.com/MISP/misp-taxonomies/blob/master/veris/machinetag.json">Confidence-Tags</a></strong>/<strong><a href="https://github.com/MISP/misp-taxonomies/blob/master/cssa/machinetag.json">Vetting State</a></strong>: There are huge differences in the quality of data, whether it was vetted upon sharing. As this means that the author was confident that the shared data is or at least was a good indicator of compromise.</p>
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<p><strong><a href="https://github.com/MISP/misp-taxonomies/blob/master/cssa/machinetag.json">Origin-Tags</a></strong>: Describes where the information came from, whether it was in an automated fashion or in a manual investigation. This should give an impression how value this intelligence is, as manual investigation should supersede any automatic generation of data.</p>
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<p><strong><a href="https://github.com/MISP/misp-taxonomies/blob/master/PAP/machinetag.json">PAP-Tags</a></strong>: An even more advanced approach of data classification is using the Permissible Actions Protocol. It indicates how the received data can be used to search for compromises within the individual company or constituency.</p>
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The full list of available taxonomies can be found <strong><a href="https://github.com/MISP/misp-taxonomies">misp-taxonomies</a></strong>.
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<h3 id="_expressing_confidenceestimative_probability_in_an_analysis">Expressing confidence/estimative probability in an analysis</h3>
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Expressing the confidence or the lack of it in an analysis is a critical step to help a partner or a third-party to check your hypotheses and conclusions.
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<p>Analysis or reports are often shared together with technical details, but often lack the associated overall confidence level.</p>
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<p>To ascertain this confidence level you can use for example the MISP <a href="#MISPTaxonomies">MISP Taxonomies</a> called <a href="https://www.misp-project.org/taxonomies.html#_admiralty_scale">admiralty-scale</a> and/or <a href="https://www.misp-project.org/taxonomies.html#_estimative_language">estimative-language</a>.</p>
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<p>This is a very human way to describe either globally an event or individual indicators of an event, with a set of easy to read human tags. (e.g: <code>admiralty-scale:source-reliability="a/b/c&#8230;&#8203;"</code>, <code>estimative-language:likelihood-probability="almost-no-chance"</code>, <code>estimative-language:confidence-in-analytic-judgment="moderate"</code>).</p>
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<p>Generally it is good practice to do this globally for the event as this will enrich the trust/value if set. If it&#8217;s a specific attribute, then the confidence can be described at more granular levels.</p>
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<p>Thus, adding confidence or estimative probability has multiple advantages such as:</p>
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<p>Allow receiving organisations to filter, classify and score the information in an automated way based on related tags</p>
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<p>Information with low-confidence can still be shared and reach communities or organisations interested in such information without impacting organisations filtering out by increased confidence level</p>
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<p>Support counter analyses and competitive analyses to validate hypotheses expressed in original reporting</p>
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<p>Expressing confidence allows the use of in the <a href="https://www.misp-project.org/2019/09/12/Decaying-Of-Indicators.html/">decaying indicators feature</a> in MISP to lower or increase the lifetime of an information</p>
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<p>Complement analysis with contrary evidences is also very welcome to ensure the original analysis and the hypotheses are properly evaluated.</p>
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<a href="#MISPTaxonomies">MISP Taxonomies</a> contain an exhaustive list of confidence levels including words of <a href="https://www.misp-project.org/taxonomies.html#_estimative_language">estimative probability</a> or confidence in analytic judgment.
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