Suspicious XOR Encoded PowerShell Command

calendar Aug 12, 2024 · attack.defense-evasion attack.execution attack.t1059.001 attack.t1140 attack.t1027  ·
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Detects presence of a potentially xor encoded powershell command

Sigma rule (View on GitHub)

 1title: Suspicious XOR Encoded PowerShell Command
 2id: bb780e0c-16cf-4383-8383-1e5471db6cf9
 3related:
 4    - id: 5b572dcf-254b-425c-a8c5-d9af6bea35a6
 5      type: obsolete
 6status: test
 7description: Detects presence of a potentially xor encoded powershell command
 8references:
 9    - https://speakerdeck.com/heirhabarov/hunting-for-powershell-abuse?slide=65
10    - https://redcanary.com/blog/yellow-cockatoo/
11    - https://zero2auto.com/2020/05/19/netwalker-re/
12    - https://mez0.cc/posts/cobaltstrike-powershell-exec/
13author: Sami Ruohonen, Harish Segar, Tim Shelton, Teymur Kheirkhabarov, Vasiliy Burov, oscd.community, Nasreddine Bencherchali
14date: 2018-09-05
15modified: 2023-01-30
16tags:
17    - attack.defense-evasion
18    - attack.execution
19    - attack.t1059.001
20    - attack.t1140
21    - attack.t1027
22logsource:
23    category: process_creation
24    product: windows
25detection:
26    selection_img:
27        - Image|endswith:
28              - '\powershell.exe'
29              - '\pwsh.exe'
30        - OriginalFileName:
31              - 'PowerShell.EXE'
32              - 'pwsh.dll'
33        - Description: 'Windows PowerShell'
34        - Product: 'PowerShell Core 6'
35    selection_cli_xor:
36        CommandLine|contains: 'bxor'
37    selection_cli_other:
38        CommandLine|contains:
39            - 'ForEach'
40            - 'for('
41            - 'for '
42            - '-join '
43            - "-join'"
44            - '-join"'
45            - '-join`'
46            - '::Join'
47            - '[char]'
48    condition: all of selection_*
49falsepositives:
50    - Unknown
51level: medium

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