Windows Event Forwarding for Network Defense

Thanks for the great write up! I’ve just started experimenting with WEF for use in the enterprise and I’ve come across an odd scenario that I have not seen documented elsewhere. I have WEF setup with a simple Powershell subscription that includes 4103 and 4104 event IDs. I’ve tried it with a few simple PS scripts, and everything works as expected.

However, I got a little more ambitious and ran a 2MB mimikatz script that had Base64 encoded executables embedded in it. The appropriate 4103 and 4104 (script block logging) events were generated on the endpoint. However, instead of forwarding the events to my collector, the subscription for Powershell events started ‘flapping’ and alternating between the subscription being created and removed (event IDs 100 and 103, respectively in the Eventlog-ForwardingPlugin channel). There are 200+ sizable 4104 events being generated by the script, so I wonder if the size/number of the events is causing an issue. Thoughts?

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