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From Nick Allen <n...@nickallen.org>
Subject [Discuss] Improve Alerting
Date Wed, 01 Feb 2017 19:11:24 GMT
I'd like to explore the functionality that we have in Metron using a
motivating example.  I think this will help highlight some gaps where we
can enhance Metron.

The motivating example is that I would like to create an alert if the
number of inbound flows to any host over a 15 minute interval is abnormal.
I would like the alert to contain the specific information below to
streamline the triage process.

Rule: Abnormal number of inbound flows
Bin: 15 mins
Alert: The host 'powned.svr.bank.com' has '230' inbound flows, exceeding
the threshold of '202'


*What Works*

In some ways, this example is similar to the "Outlier Detection" demo that
I performed with the Profiler a few months back.   We have most of what we
need to do this with a couple caveats.

1. An enrichment would be added to enrich the message with the correct
internal hostname 'powned.svr.bank.com'.

2. With the Profiler, I can capture some idea of what "normal" is for the
number of inbound flows across 15 minute intervals.
3. With Threat Triage, I can create rules that alert when a value exceeds
what the Profiler defines as normal.


*What's Missing*

Its nice to know that we are almost all the way there with this example.
Unfortunately, there are two gaps that fall out of this.

 1. *Threat Triage Transparency*

There is little transparency into the Threat Triage process itself.  When
Threat Triage runs, all I get is a score.  I don't know how that score was
arrived at, which rules were triggered, and the specific values that caused
a rule to trigger.

More specifically, there is no way to generate a message that looks like
"The host 'powned.svr.bank.com' has '230' inbound flows, exceeding the
threshold of '202'".


2. *Triage Calculated Values from the Profiler*

Also, the value being interrogated here, the number of inbound flows, is
not a static value contained within any single telemetry message.  This
value is calculated across multiple messages by the Profiler.  The current
Threat Triage process cannot be used to interrogate values calculated by
the Profiler.


To try and keep this email concise and digestible, I am going to send a
follow-on discussing proposed solutions for each of these separately.

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