It is always DNS (PowerShell Edition)

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For those following along with ATT&CK this entry is about Application Layer Protocol: DNS, Command And Control technique T1071 and PowerShell, Execution technique T1086.




Having written a bit about DNSCat2 previously I wanted to check out PowerShell implementations like dnscat2-powershell and see what I could turn up in logs. I tried running various commands through the shell from the server side and discovered the following:




PowerShell calls nslookup.exe to communicate with the server side of DNScat2 and executes commands issued through that shell, we can hunt for this:

index=win10 sourcetype="wineventlog:security" EventCode=4688 Creator_Process_Name=C:\\Windows\\*\\WindowsPowerShell\\*\\powershell.exe
| stats count(New_Process_Name) AS Count values(New_Process_Name) AS Processes BY Account_Name Creator_Process_Name


Our results will look like this:




We can look specifically for calls to nslookup by PowerShell and count the events with this SPL:


index=win10 sourcetype="wineventlog:security" EventCode=4688 Creator_Process_Name=C:\\Windows\\*\\WindowsPowerShell\\*\\powershell.exe New_Process_Name=*nslookup.exe
| stats count(New_Process_Name) AS Count values(New_Process_Name) AS Processes BY Account_Name Creator_Process_Name


And our results will look something like this, thousands of nslookup.exe processes spawned by PowerShell:



 

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