1type: trigger
2name: sigmahq/proc_creation_win_powershell_cmdline_special_characters
3description: |
4  Detects the PowerShell command lines with special characters
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 matches '\\+.*\\+.*\\+.*\\+.*\\+.*\\+.*\\+.*\\+.*\\+.*\\+.*\\+.*\\+.*\\+.*\\+' || evt.Parsed.CommandLine matches '\\{.*\\{.*\\{.*\\{.*\\{.*\\{.*\\{.*\\{.*\\{.*\\{' || evt.Parsed.CommandLine matches '\\^.*\\^.*\\^.*\\^.*\\^' || evt.Parsed.CommandLine matches '`.*`.*`.*`.*`') && not (evt.Parsed.ParentImage == 'C:\\Program Files\\Amazon\\SSM\\ssm-document-worker.exe' || evt.Parsed.CommandLine contains 'new EventSource("Microsoft.Windows.Sense.Client.Management"' || evt.Parsed.CommandLine contains 'public static extern bool InstallELAMCertificateInfo(SafeFileHandle handle);'))
7blackhole: 2m
8#status: test
9labels:
10  service: windows
11  confidence: 1
12  spoofable: 0
13  classification:
14   - attack.t1027
15   - attack.t1059.001
16
17  label: "Potential PowerShell Command Line Obfuscation"
18  behavior : "windows:audit"
19  remediation: false
20
21scope:
22  type: ParentProcessId
23  expression: evt.Parsed.ParentProcessId
24
25