Powershell download and load assembly

 1title: Powershell download and load assembly 
 2status: experimental
 3description: Detect powershell download and load assembly 
 4author: Joe Security
 5date: 2019-11-25
 6id: 200030
 7threatname:
 8behaviorgroup: 1
 9classification: 8
10mitreattack: 
11
12logsource:
13    category: process_creation
14    product: windows
15detection:
16    selection:
17        CommandLine:
18            - '*powershell*Downloadstring(*.Load([Convert]::Frombase64String(*'
19            - '*).downloadstring(*[reflection.assembly]::load($*'
20            - '*invoke-webrequest*[system.reflection.assembly]::loadfile($*'
21            - '*.downloaddata($*[system.reflection.assembly]::load($*'
22            
23    condition: selection
24level: critical