ArcSight Pro Tip #1 - type field

Welcome to the first of a 100 best practice posts, these range from newbie to advanced user and consist of tips, tricks and best practices for ArcSight.

Filter Criteria: type

When using the "event.type" CEF field in a filter or rule you have the following options:

Action, Base, Aggregated, Correlation

This is likely a field you want to leverage in ALL content!  Why? 

Well it specifies if you want to fire a correlation event from a base or non-correlation events, or subsequently if you would like your correlation event to be based on another correlation event!  You can have rules that trigger other rules and so on but be warned! 

Rules that do not specify:

type != Correlation 

Can easily end up in an infinite loop

Therefore this ArcSight Pro Tip is to begin all rule content specifically with this filter entry unless you specifically want to match on rule generated events (non-base events):

type != Correlation

Reminder != means "not equal to"


Happy hacking!


Greg

@threatstream

http://www.threatstream.com

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  • Well, in fact If you use "type!=correlated", it will match both base and aggregated events (as well as any other types, if there are or will be any). Because aggregation at connector level never sets type to "correlated".

    But many stock rules use "type=base" and that will lead to situation you described  - after enabling aggregation at connectors, those rules will not process aggregated events.

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  • Well, in fact If you use "type!=correlated", it will match both base and aggregated events (as well as any other types, if there are or will be any). Because aggregation at connector level never sets type to "correlated".

    But many stock rules use "type=base" and that will lead to situation you described  - after enabling aggregation at connectors, those rules will not process aggregated events.

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