From a816f4775fd2edc3de54eba887b59ef52b992c2f Mon Sep 17 00:00:00 2001
From: Florian Roth <florian.roth@bsk-consulting.de>
Date: Wed, 29 Jan 2020 16:05:12 +0100
Subject: [PATCH] rule: FromBase64String command line

---
 .../win_powershell_frombase64string.yml       | 21 +++++++++++++++++++
 1 file changed, 21 insertions(+)
 create mode 100644 rules/windows/process_creation/win_powershell_frombase64string.yml

diff --git a/rules/windows/process_creation/win_powershell_frombase64string.yml b/rules/windows/process_creation/win_powershell_frombase64string.yml
new file mode 100644
index 00000000..dc680596
--- /dev/null
+++ b/rules/windows/process_creation/win_powershell_frombase64string.yml
@@ -0,0 +1,21 @@
+title: FromBase64String Command Line
+id: e32d4572-9826-4738-b651-95fa63747e8a
+status: experimental
+description: Detects suspicious FromBase64String expressions in command line arguments
+references:
+    - https://gist.github.com/Neo23x0/6af876ee72b51676c82a2db8d2cd3639
+author: Florian Roth
+date: 2020/01/29
+tags: 
+    - attack.t1027
+    - attack.defense_evasion
+logsource:
+    category: process_creation
+    product: windows
+detection:
+    selection:
+        CommandLine|contains: '::FromBase64String('
+    condition: selection
+falsepositives:
+    - Administrative script libraries
+level: high