AMSI Bypass Pattern Assembly GetType

calendar Aug 12, 2024 · attack.defense-evasion attack.t1562.001 attack.execution  ·
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Detects code fragments found in small and obfuscated AMSI bypass PowerShell scripts

Sigma rule (View on GitHub)

 1title: AMSI Bypass Pattern Assembly GetType
 2id: e0d6c087-2d1c-47fd-8799-3904103c5a98
 3status: test
 4description: Detects code fragments found in small and obfuscated AMSI bypass PowerShell scripts
 5references:
 6    - https://www.mdsec.co.uk/2018/06/exploring-powershell-amsi-and-logging-evasion/
 7    - https://twitter.com/cyb3rops/status/1588574518057979905?s=20&t=A7hh93ONM7ni1Rj1jO5OaA
 8author: Florian Roth (Nextron Systems)
 9date: 2022-11-09
10tags:
11    - attack.defense-evasion
12    - attack.t1562.001
13    - attack.execution
14logsource:
15    product: windows
16    category: ps_script
17    definition: 'Requirements: Script Block Logging must be enabled'
18detection:
19    selection:
20        ScriptBlockText|contains|all:
21            - '[Ref].Assembly.GetType'
22            - 'SetValue($null,$true)'
23            - 'NonPublic,Static'
24    condition: selection
25falsepositives:
26    - Unknown
27level: high

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