Suspicious Obfuscated PowerShell Code

 1title: Suspicious Obfuscated PowerShell Code
 2id: 8d01b53f-456f-48ee-90f6-bc28e67d4e35
 3status: test
 4description: Detects suspicious UTF16 and base64 encoded and often obfuscated PowerShell code often used in command lines
 5references:
 6    - https://app.any.run/tasks/fcadca91-3580-4ede-aff4-4d2bf809bf99/
 7author: Florian Roth (Nextron Systems)
 8date: 2022/07/11
 9modified: 2023/02/14
10tags:
11    - attack.defense_evasion
12logsource:
13    category: process_creation
14    product: windows
15detection:
16    selection:
17        CommandLine|contains:
18            #  -bxor 0x
19            - 'IAAtAGIAeABvAHIAIAAwAHgA'
20            - 'AALQBiAHgAbwByACAAMAB4A'
21            - 'gAC0AYgB4AG8AcgAgADAAeA'
22            # .Invoke() |
23            - 'AC4ASQBuAHYAbwBrAGUAKAApACAAfAAg'
24            - 'AuAEkAbgB2AG8AawBlACgAKQAgAHwAI'
25            - 'ALgBJAG4AdgBvAGsAZQAoACkAIAB8AC'
26            # {1}{0}" -f
27            # {0}{3}" -f
28            # {2}{0}" -f
29            - 'AHsAMQB9AHsAMAB9ACIAIAAtAGYAI'
30            - 'B7ADEAfQB7ADAAfQAiACAALQBmAC'
31            - 'AewAxAH0AewAwAH0AIgAgAC0AZgAg'
32            - 'AHsAMAB9AHsAMwB9ACIAIAAtAGYAI'
33            - 'B7ADAAfQB7ADMAfQAiACAALQBmAC'
34            - 'AewAwAH0AewAzAH0AIgAgAC0AZgAg'
35            - 'AHsAMgB9AHsAMAB9ACIAIAAtAGYAI'
36            - 'B7ADIAfQB7ADAAfQAiACAALQBmAC'
37            - 'AewAyAH0AewAwAH0AIgAgAC0AZgAg'
38            # {1}{0}' -f
39            # {0}{3}' -f
40            # {2}{0}' -f
41            - 'AHsAMQB9AHsAMAB9ACcAIAAtAGYAI'
42            - 'B7ADEAfQB7ADAAfQAnACAALQBmAC'
43            - 'AewAxAH0AewAwAH0AJwAgAC0AZgAg'
44            - 'AHsAMAB9AHsAMwB9ACcAIAAtAGYAI'
45            - 'B7ADAAfQB7ADMAfQAnACAALQBmAC'
46            - 'AewAwAH0AewAzAH0AJwAgAC0AZgAg'
47            - 'AHsAMgB9AHsAMAB9ACcAIAAtAGYAI'
48            - 'B7ADIAfQB7ADAAfQAnACAALQBmAC'
49            - 'AewAyAH0AewAwAH0AJwAgAC0AZgAg'
50    condition: selection
51falsepositives:
52    - Unknown
53level: high