1type: trigger
2name: sigmahq/proc_creation_win_powershell_base64_encoded_cmd
3description: |
4  Detects suspicious powershell process starts with base64 encoded commands (e.g. Emotet)
5filter: |
6  (evt.Meta.service == 'sysmon' && evt.Parsed.EventID == '1') && ((evt.Parsed.Image endsWith '\\powershell.exe' || evt.Parsed.Image endsWith '\\pwsh.exe' || evt.Parsed.OriginalFileName in ['PowerShell.EXE', 'pwsh.dll']) && (evt.Parsed.CommandLine contains ' -e' && (evt.Parsed.CommandLine contains ' JAB' || evt.Parsed.CommandLine contains ' SUVYI' || evt.Parsed.CommandLine contains ' SQBFAFgA' || evt.Parsed.CommandLine contains ' aQBlAHgA' || evt.Parsed.CommandLine contains ' aWV4I' || evt.Parsed.CommandLine contains ' IAA' || evt.Parsed.CommandLine contains ' IAB' || evt.Parsed.CommandLine contains ' UwB' || evt.Parsed.CommandLine contains ' cwB') || evt.Parsed.CommandLine contains '.exe -ENCOD ' || evt.Parsed.CommandLine contains ' BA^J e-') && not (evt.Parsed.CommandLine contains ' -ExecutionPolicy remotesigned '))
7blackhole: 2m
8#status: test
9labels:
10  service: windows
11  confidence: 1
12  spoofable: 0
13  classification:
14   - attack.t1059.001
15
16  label: "Suspicious Encoded PowerShell Command Line"
17  behavior : "windows:audit"
18  remediation: false
19
20scope:
21  type: ParentProcessId
22  expression: evt.Parsed.ParentProcessId
23
24