mirror of https://github.com/MISP/misp-training
388 lines
15 KiB
TeX
388 lines
15 KiB
TeX
% DO NOT COMPILE THIS FILE DIRECTLY!
|
|
% This is included by the other .tex files.
|
|
|
|
\begin{frame}[t,plain]
|
|
\titlepage
|
|
\end{frame}
|
|
|
|
\section{Expiring IOCs: Why and How?}
|
|
\begin{frame}
|
|
\frametitle{Indicators - Problem Statement}
|
|
\begin{itemize}
|
|
\item Various users and organisations can share data via MISP, multiple parties can be involved
|
|
\begin{itemize}
|
|
\item \textbf{Trust}, \textbf{data quality} and \textbf{time-to-live} issues
|
|
\item Each user/organisation has \textbf{different use-cases} and interests
|
|
\begin{itemize}
|
|
\item Conflicting interests such as operational security, attribution,... (depends on the user)
|
|
\end{itemize}
|
|
\end{itemize}
|
|
\item[] $\rightarrow$ Can be partially solved with \textit{Taxonomies}
|
|
\pause
|
|
\vspace{0.5cm}
|
|
\item Attributes can be shared in large quantities (more than 7.3 million on \texttt{MISPPRIV})
|
|
\begin{itemize}
|
|
\item Partial info about their \textbf{freshness} (\textit{Sightings})
|
|
\item Partial info about their \textbf{validity} (last update)
|
|
\end{itemize}
|
|
\item[] $\rightarrow$ Can be partially solved with our \textit{Decaying model}
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Requirements to enjoy the decaying feature in MISP}
|
|
\begin{itemize}
|
|
\item Starting from \textbf{MISP 2.4.116}, the decaying feature is available
|
|
\item Don't forget to update the decay models and enable the ones you want
|
|
\item The decaying feature has no impact on the information in MISP, it's just an overlay to be used in the user-interface and API
|
|
\item Decay strongly relies on \textit{Taxonomies} and \textit{Sightings}, don't forget to review their configuration
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{\textit{Sightings} - Refresher}
|
|
\textit{Sightings} add temporal context to indicators.
|
|
A user, script or an IDS can extend the information related to indicators by reporting back to MISP that
|
|
an indicator has been \texttt{seen}, or that an indicator can be considered as a \texttt{false-positive}
|
|
\vspace{0.5cm}
|
|
\begin{itemize}
|
|
\item \textit{Sightings} give more credibility/visibility to indicators
|
|
\item This information can be used to {\bf prioritise and decay indicators}
|
|
\end{itemize}
|
|
\begin{center}
|
|
\includegraphics[scale=1.00]{pics/sightings.png}
|
|
\end{center}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Organisations opt-in - setting a level of confidence}
|
|
MISP is a peer-to-peer system, information passes through multiple instances.
|
|
\begin{itemize}
|
|
\item \textbf{Producers can add context} (such as tags from \textit{Taxonomies}, \textit{Galaxies}) about their asserted confidence or the reliability of the data
|
|
\item Consumers can have \textbf{different levels of trust} in the producers and/or analysts themselves
|
|
\item Users might have other contextual needs
|
|
\end{itemize}
|
|
\begin{center}
|
|
$\rightarrow$ Achieved thanks to \textit{Taxonomies}
|
|
\end{center}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Taxonomies - Refresher (1)}
|
|
\includegraphics[width=1.00\linewidth]{pics/taxonomies.png}
|
|
\begin{itemize}
|
|
\item Tagging is a simple way to attach a classification to an \textit{Event} or an \textit{Attribute}
|
|
\item Classification must be globally used to be efficient
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Taxonomies - Refresher (2)}
|
|
\includegraphics[width=1.00\linewidth]{pics/taxonomy-admiralty-scale.png}
|
|
\begin{center}
|
|
$\rightarrow$ Cherry-pick allowed \textit{Tags}
|
|
\end{center}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Taxonomies - Refresher (3)}
|
|
\begin{itemize}
|
|
\item Some taxonomies have \texttt{numerical\_value}
|
|
\begin{itemize}
|
|
\item[$\rightarrow$] Can be used to prioritise \textit{Attributes}
|
|
\end{itemize}
|
|
\end{itemize}
|
|
\vspace{1cm}
|
|
|
|
\begin{footnotesize}
|
|
\begin{columns}[T] % align columns
|
|
\begin{column}{.40\textwidth}
|
|
\begin{tabular}{|ll|}
|
|
\hline
|
|
\textbf{Description} & \textbf{Value}\\
|
|
\hline
|
|
Completely reliable & 100\\
|
|
Usually reliable & 75\\
|
|
Fairly reliable & 50\\
|
|
Not usually reliable & 25\\
|
|
Unreliable & 0\\
|
|
Reliability cannot be judged & 50 \textbf{\color{red}?}\\
|
|
Deliberatly deceptive & 0 \textbf{\color{red}?}\\
|
|
\hline
|
|
\end{tabular}
|
|
\end{column}%
|
|
\hfill%
|
|
\begin{column}{.48\textwidth}
|
|
\begin{tabular}{|ll|}
|
|
\hline
|
|
\textbf{Description} & \textbf{Value}\\
|
|
\hline
|
|
Confirmed by other sources & 100\\
|
|
Probably true & 75\\
|
|
Possibly true & 50\\
|
|
Doubtful & 25\\
|
|
Improbable & 0\\
|
|
Truth cannot be judged & 50 \textbf{\color{red}?}\\
|
|
\hline
|
|
\end{tabular}
|
|
\end{column}%
|
|
\end{columns}
|
|
\end{footnotesize}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Scoring Indicators: Our solution}
|
|
$$ \texttt{score}(\texttt{\tiny Attribute}) = \texttt{base\_score}(\texttt{\tiny Attribute, Model}) \;\;\bullet\;\; \texttt{decay}(\texttt{\tiny Model, time}) $$
|
|
Where,\vspace{0.5cm}
|
|
\begin{itemize}
|
|
\item \texttt{score} $ \in [0, +\infty $
|
|
\item \texttt{base\_score} $ \in [0, 100] $
|
|
\item \texttt{decay} is a function defined by model's parameters controlling decay speed
|
|
\item \texttt{Attribute} Contains \textit{Attribute}'s values and metadata {\scriptsize (\textit{Taxonomies}, \textit{Galaxies}, ...)}
|
|
\item \texttt{Model} Contains the \textit{Model}'s configuration
|
|
\end{itemize}
|
|
|
|
\end{frame}
|
|
|
|
\section{Current implementation in MISP}
|
|
\begin{frame}
|
|
\frametitle{Implementation in MISP: \texttt{Event/view}}
|
|
\includegraphics[width=1.00\linewidth]{pics/decaying-event.png}
|
|
\begin{itemize}
|
|
\item \texttt{Decay score} toggle button
|
|
\begin{itemize}
|
|
\item Shows Score for each \textit{Models} associated to the \textit{Attribute} type
|
|
\end{itemize}
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\begin{frame}[fragile]
|
|
\frametitle{Implementation in MISP: API result}
|
|
\texttt{/attributes/restSearch}
|
|
\begin{lstlisting}
|
|
"Attribute": [
|
|
{
|
|
"category": "Network activity",
|
|
"type": "ip-src",
|
|
"to_ids": true,
|
|
"timestamp": "1565703507",
|
|
[...]
|
|
"value": "8.8.8.8",
|
|
"decay_score": [
|
|
{
|
|
"score": 54.475223849544456,
|
|
"decayed": false,
|
|
"DecayingModel": {
|
|
"id": "85",
|
|
"name": "NIDS Simple Decaying Model"
|
|
}
|
|
}
|
|
],
|
|
[...]
|
|
\end{lstlisting}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Implementation in MISP: Playing with Models}
|
|
\begin{itemize}
|
|
\item \textbf{Automatic scoring} based on default values
|
|
\item \textbf{User-friendly UI} to manually set \textit{Model} configuration (lifetime, decay, etc.)
|
|
\item \textbf{Simulation} tool
|
|
\item Interaction through the \textbf{API}
|
|
\item Opportunity to create your \textbf{own} formula or algorythm
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\section{Decaying Models in Depth}
|
|
\begin{frame}
|
|
\frametitle{Scoring Indicators: \texttt{base\_score} (1)}
|
|
$$ \texttt{score}(\texttt{\tiny Attribute}) = \texttt{base\_score}(\texttt{\tiny Attribute, Model}) \;\;\bullet\;\; {\color{gray}\texttt{decay}(\texttt{\tiny Model, time})} $$
|
|
When scoring indicators\footnote{Paper available: \url{https://arxiv.org/pdf/1803.11052}}, multiple parameters\footnote{at a variable extent as required} can be taken into account. The {\bf base score} is calculated with the following in mind:
|
|
\begin{itemize}
|
|
\item {\color{purple}Data reliability, credibility, analyst skills, custom prioritisation tags (economical-impact), etc.}
|
|
\item {\color{orange}Trust in the source}
|
|
\end{itemize}
|
|
\vspace{0.3cm}
|
|
$$\texttt{base\_score} = \omega_{tg} \cdot {\color{purple}tags} + \omega_{sc} \cdot {\color{orange}source\_confidence}$$
|
|
Where,
|
|
\begin{itemize}
|
|
\item[] $\omega_{sc} + \omega_{tg} = 1$
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Scoring Indicators: \texttt{base\_score} (2)}
|
|
Current implentation ignores \texttt{source\_confidence}:
|
|
$$\rightarrow \texttt{base\_score} = tags$$
|
|
\includegraphics[width=1.0\linewidth]{pics/bs-computation-steps.png}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Scoring Indicators: decay speed (1)}
|
|
$$ \texttt{score}(\texttt{\tiny Attribute}) = {\color{gray}\texttt{base\_score}(\texttt{\tiny Attribute, Model})} \;\;\bullet\;\; \texttt{decay}(\texttt{\tiny Model, time}) $$
|
|
The \texttt{decay} is calculated using:
|
|
\begin{itemize}
|
|
\item The \texttt{lifetime} of the indicator
|
|
\begin{itemize}
|
|
\item May vary depending on the indicator type
|
|
\item short for an IP, long for an hash
|
|
\end{itemize}
|
|
\item The \texttt{decay rate}, or speed at which an attribute loses score over time
|
|
\item The \texttt{time} elapsed since the latest update or sighting
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Scoring Indicators: putting it all toghether}
|
|
$\rightarrow$ \texttt{decay rate} is \textbf{re-initialized upon sighting} addition, or said differently, the \texttt{score} is reset to its base score as new \textit{sightings} are applied.
|
|
$$score = base\_score \cdot \left( 1 - \left( \frac{t}{\tau} \right)^{\frac{1}{\delta}} \right) $$
|
|
\begin{itemize}
|
|
\item $\tau = $ \texttt{lifetime}
|
|
\item $\delta = $ \texttt{decay speed}
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Implementation in MISP: Models definition}
|
|
\hspace{190pt}
|
|
\raisebox{-1.0ex}{\Large $\Rsh$} {\tiny $score = base\_score \cdot \left( 1 - \left( \frac{t}{\tau} \right)^{\frac{1}{\delta}} \right) $}
|
|
\textit{Models} are an instanciation of the formula where elements can be defined:
|
|
\begin{itemize}
|
|
\item Parameters: \texttt{lifetime, decay\_rate, threshold}
|
|
\item \texttt{base\_score}
|
|
\item \texttt{default base\_score}
|
|
\item formula
|
|
\item associate \textit{Attribute} types
|
|
\item creator organisation
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Implementation in MISP: Models Types}
|
|
Multiple model types are available
|
|
\begin{itemize}
|
|
\item \textbf{Default Models}: Models created and shared by the community. Available from \texttt{misp-decaying-models} repository\footnote{\url{https://github.com/MISP/misp-decaying-models.git}}.
|
|
\begin{itemize}
|
|
\item $\rightarrow$ Not editable
|
|
\end{itemize}
|
|
\item \textbf{Organisation Models}: Models created by a user belonging to an organisation
|
|
\begin{itemize}
|
|
\item These models can be hidden or shared to other organisation
|
|
\item $\rightarrow$ Editable
|
|
\end{itemize}
|
|
\end{itemize}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Implementation in MISP: Index}
|
|
\includegraphics[width=1.00\linewidth]{pics/decaying-index.png}
|
|
View, update, add, create, delete, enable, export, import
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Implementation in MISP: Fine tuning tool}
|
|
\includegraphics[width=1.00\linewidth]{pics/decaying-tool.png}
|
|
Create, modify, visualise, perform mapping
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Implementation in MISP: \texttt{base\_score} tool}
|
|
\includegraphics[width=1.00\linewidth]{pics/decaying-basescore.png}
|
|
Adjust Taxonomies relative weights
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Implementation in MISP: simulation tool}
|
|
\includegraphics[width=1.00\linewidth]{pics/decaying-simulation.png}
|
|
Simulate \textit{Attributes} with different \textit{Models}
|
|
\end{frame}
|
|
|
|
\begin{frame}[fragile]
|
|
\frametitle{Implementation in MISP: API query body}
|
|
\texttt{/attributes/restSearch}
|
|
\begin{lstlisting}
|
|
{
|
|
"includeDecayScore": 1,
|
|
"includeFullModel": 0,
|
|
"excludeDecayed": 0,
|
|
"decayingModel": [85],
|
|
"modelOverrides": {
|
|
"threshold": 30
|
|
}
|
|
"score": 30,
|
|
}
|
|
\end{lstlisting}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Creating a new decay algorithm (1)}
|
|
The current architecture allows users to create their \textbf{own} formulae.
|
|
|
|
\begin{enumerate}
|
|
\item Create a new file \texttt{{\$}filename} in \texttt{app/Model/DecayingModelsFormulas/}
|
|
\item Extend the Base class as defined in \texttt{DecayingModelBase}
|
|
\item Implement the two mandatory functions \texttt{computeScore} and \texttt{isDecayed} using your own formula/algorithm
|
|
\item Create a Model and set the formula field to \texttt{{\$}filename}
|
|
\end{enumerate}
|
|
|
|
Use cases:
|
|
\begin{itemize}
|
|
\item Add support for \textbf{more feature} (expiration taxonomy)
|
|
\item \textbf{Query external services} then influence the score
|
|
\item Completely \textbf{different approach} (i.e streaming algorithm)
|
|
\item ...
|
|
\end{itemize}
|
|
|
|
\end{frame}
|
|
|
|
\lstset{language=PHP}
|
|
\begin{frame}[fragile]
|
|
\frametitle{Creating a new decay algorithm (2)}
|
|
\lstset{basicstyle=\scriptsize}
|
|
\begin{lstlisting}
|
|
<?php
|
|
include_once 'Base.php';
|
|
|
|
class Polynomial extends DecayingModelBase
|
|
{
|
|
public const DESCRIPTION = 'The description of your new decaying algorithm';
|
|
|
|
public function computeScore($model, $attribute, $base_score, $elapsed_time)
|
|
{
|
|
// algorithm returning a numerical score
|
|
}
|
|
|
|
public function isDecayed($model, $attribute, $score)
|
|
{
|
|
// algorithm returning a boolean stating
|
|
// if the attribute is expired or not
|
|
}
|
|
}
|
|
?>
|
|
\end{lstlisting}
|
|
\end{frame}
|
|
|
|
\begin{frame}
|
|
\frametitle{Decaying Models 2.0}
|
|
\begin{itemize}
|
|
\item Improved support of \textit{Sightings}
|
|
\begin{itemize}
|
|
\item \texttt{False positive} \textit{Sightings} should somehow reduce the score
|
|
\item \texttt{Expiration} \textit{Sightings} should mark the attribute as decayed
|
|
\end{itemize}
|
|
\item Potential \textit{Model} improvements
|
|
\begin{itemize}
|
|
\item Instead of resetting the score to \texttt{base\_score} once a \textit{Sighting} is set, the score should be increased additively (based on a defined coefficient); thus \textbf{prioritizing surges} rather than infrequent \textit{Sightings}
|
|
\item Take into account related \textit{Tags} or \textit{Correlations} when computing score
|
|
\end{itemize}
|
|
\item Increase \textit{Taxonomy} coverage
|
|
\begin{itemize}
|
|
\item Users should be able to manually override the \texttt{numerical\_value} of \textit{Tags}
|
|
\end{itemize}
|
|
\item For specific type, take into account data from other services
|
|
\begin{itemize}
|
|
\item Could fetch data from \textit{BGP ranking}, \textit{Virus Total}, \textit{Passive X} for IP/domain/... and adapt the score
|
|
\end{itemize}
|
|
\end{itemize}
|
|
\end{frame}
|