Added Sigma Rules

rules/Sigma/sysmon_direct_syscall_ntopenprocess.yml

@@ -0,0 +1,27 @@
+title: Direct Syscall of NtOpenProcess
+author: Christian Burkard
+date: 2021/07/28
+description: Detects the usage of the direct syscall of NtOpenProcess which might
+    be done from a CobaltStrike BOF.
+detection:
+    SELECTION_1:
+        EventID: 10
+    SELECTION_2:
+        CallTrace: UNKNOWN*
+    condition: (SELECTION_1 and SELECTION_2)
+falsepositives:
+- unknown
+id: 3f3f3506-1895-401b-9cc3-e86b16e630d0
+level: critical
+logsource:
+    category: process_access
+    product: windows
+references:
+- https://medium.com/falconforce/falconfriday-direct-system-calls-and-cobalt-strike-bofs-0xff14-741fa8e1bdd6
+status: experimental
+tags:
+- attack.execution
+- attack.t1106
+yml_filename: sysmon_direct_syscall_ntopenprocess.yml
+yml_path: /Users/user/Documents/YamatoSecurity/sigma/rules/windows/process_access
+