Working with large Event Log files – evtx

If you ever have to work with large evtx files you will love what Message Analyzer can do for you.

Recently I looked into a busy print server that was generating thousands of security audit events  per second. The sysadmin provided me with a 4GB evtx file (3.2 million events) to look at. Now, if you have ever tried filtering a file this big in the MMC you know its a problem. Even trying to export to XML or CSV from the MMC doesn’t seem to work well.

My task was to identify the top event IDs and then for the top events find out what they were about. I used LogParer to get a count of top event count but the real hard part was getting at the EventData, The EventData is unique to a particular Event ID. In my case I knew the top events were object access audit events but I really needed know by who (the SubjectUserName) and what are they touching. Both these fields are in EventData and I needed to export that info so I could get it into PowerPivot to summarize. This is where Message Analyzer came to my rescue.

Using Message Analyzer 1.3.1 I was able to load all of the evtx relatively quickly. Filter to a specific event id (fast), and then right click on the EventData fields I wanted and add as columns (fast).  Just like that I had on the screen the data I needed. From there its a simple export to CSV, load into PowerPivot and quickly I could see that the 90% of the events were from a  program touching dll and log files. We can now adjust our audit policy to fix this.

I hope you find this helpful.

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