Details
-
Improvement
-
Status: Done
-
Major
-
Resolution: Done
-
0.3.1
-
None
Description
Problem
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'". This makes it difficult for an analyst to action the alert.
Proposed Solution
To improve the transparency of the Threat Triage process, I am proposing these enhancements.
(1) Threat Triage should attach to each message all of the rules that fired in addition to the total calculated threat triage score.
(2) Threat Triage should allow a custom message to be generated for each rule. The custom message would allow for some form of string interpolation so that I can add specific values from each message to the generated alert. We could allow this in one or both of the new fields that Casey just added, name and comment.
(3) The specific method of string interpolation will be implemented under a separate issue.
Example
(1) In this example, we have a telemetry message with a field called 'value' that we need to monitor. In Enrichment, I calculate some sort of value threshold, over which an alert should be generated.
(2) In Threat Triage, I use the calculated value threshold to alert on any message that has a value exceeding this threshold.
(3) By leveraging a new field called 'reason', I can embed values from the message, like the hostname, value, and value threshold, into the alert produced by Threat Triage.
"triageConfig" : { "riskLevelRules" : [ { "name" : "Abnormal DNS Port", "rule" : "source.type == 'bro' and protocol == 'dns' and ip_dst_port != 53", "score" : 10.0, "reason" : "FORMAT('Abnormal DNS Port: expected: 53, found: %s:%d', ip_dst_addr, ip_dst_port)" } ], "aggregator" : "MAX", "aggregationConfig" : { } }
(4) The Threat Triage process today would add only the total calculated score.
"threat.triage.level": 10.0
With this proposal, Threat Triage would add the following to the message.
"threat.triage.level":{ "score":10.0, "rules":[ { "name":"Abnormal DNS Port", "comment":null "score":10.0, "reason":"Abnormal DNS Port: expected: 53, found: 224.0.0.251:5353", } ] }
Attachments
Issue Links
- links to
