Add: sigma rules (#175)

rules/sigma/windows/process_creation/process_creation_dotnet.yml

@@ -0,0 +1,37 @@
+
+title: Dotnet.exe Exec Dll and Execute Unsigned Code LOLBIN
+author: Beyu Denis, oscd.community
+date: 2020/10/18
+description: dotnet.exe will execute any DLL and execute unsigned code
+detection:
+  SELECTION_1:
+    EventID: 1
+  SELECTION_2:
+    CommandLine:
+    - '*.dll'
+    - '*.csproj'
+  SELECTION_3:
+    Image:
+    - '*\dotnet.exe'
+  condition: (SELECTION_1 and SELECTION_2 and SELECTION_3)
+falsepositives:
+- System administrator Usage
+- Penetration test
+fields:
+- ComputerName
+- User
+- CommandLine
+- ParentCommandLine
+id: d80d5c81-04ba-45b4-84e4-92eba40e0ad3
+level: medium
+logsource:
+  category: process_creation
+  product: windows
+references:
+- https://github.com/LOLBAS-Project/LOLBAS/blob/master/yml/OtherMSBinaries/Dotnet.yml
+- https://twitter.com/_felamos/status/1204705548668555264
+- https://bohops.com/2019/08/19/dotnet-core-a-vector-for-awl-bypass-defense-evasion/
+status: experimental
+tags:
+- attack.execution
+- attack.t1218