Page Comparison

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Checkmk Rules needed

Configuring the Checkmk Agent

In this use case, we are only interested in the Security log, so the rule should look like this and should match all hosts we want to monitor the Security log on:

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After saving this rule, activate the changes and bake & sign your agents.

Configuring the Event Console Forwarding

If you would discover the services of your affected Windows hosts now, you will get the old-school Checkmk Services "Log Security" with the "Open Log" in their context menus.

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After saving this rule, make a service discovery on the affected hosts and activate the changes.

Checking the Event Archive

From now on, the events from the Windows Eventlog on your hosts will be translated to Checkmk Event Console events and put into the event archive (if not matching any EC Rule yet):

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We will create some EC Rules in the next paragraph to categorize and classify the incoming events. Using the message texts from the Event History, you can define the needed Regex patterns for that.

Creating the Event Console Rules

Basic Rules

First, create a Rulepack with a suitable name:

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There, create a rule to handle all events that are not matching any other rules yet:

General properties

Setup → Events → Event Console rule packs → Add Rule

Matching Criteria

Here, we need two regular expressions:

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1. The first one is applied to the message text and defines three matching groups using the brackets:
   
   

   Code Block
   language bash theme RDark
   .{3} [0-9]+ [0-9:]{8} [0-9]+\.([0-9]{4}) ([^ ]+) (.*)

   
   

   The website https://regex101.com helps you to understand how the regex matches the message text and which groups are created:
   
   
   
   These groups can later be accessed using the placeholders \1, \2, and \3 in the message text rewriting. They might also become important when automatic duplicate detection is used. We'll come to that later on.
   
   
2. The second regular expression "^(.*)$" simply matches on any Application text (in our case, it's always "Security", though) and puts it into a matching group. Later, we can access this group using the macro "$MATCH_GROUPS_SYSLOG_APPLICATION_1$".

Counting & Timing

The "Outcome & Action" section can remain unchanged, but in the Counting & Timing, we have two definitions:

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As the events that match this rule will be categorized as "unknown", we will only keep them for 4 hours to keep our Event view as small and clean as possible.

Rewriting

In the Rewriting section, we can adjust the message text, application, and other variables that will be shown in the event views:

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WinEvtLog_Unknown_Security_4799

Conclusion

Using this "unknown" rule, we will catch all so-far not categorized events, adjust their message text and application, and then aggregate ("count") them based on the hostname and that modified application.

Specific Rules

Based on the events that are now caught by the "unknown" rule, we can pick single Event IDs and create rules for them to handle them separately. Let's choose this event in the first step:

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Clone the "unknown" rule and modify the following fields:

The Regex

Using the long message text, we pick out the important information (colored) and create a regular expression pattern, starting with the one we already used in the "unknown" rule:

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Fill in the new pattern in the "Text to match" field:

Counting & Timing

The counting and timing also will be changed a bit:

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Also, we don't want to archive these events after a few hours, but after three days ( => keep over the weekend).

Rewriting

In the rewriting section, the texts are also adjusted to the newly defined event:

Further Rules and Performance Considerations

We have to create further specific rules as done in the last steps. Here are some things you have to take care of:

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