Powershell Token Obfuscation - Process Creation

calendar Nov 2, 2023 · attack.defense_evasion attack.t1027.009  ·
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Detects TOKEN OBFUSCATION technique from Invoke-Obfuscation

Sigma rule (View on GitHub)

 1title: Powershell Token Obfuscation - Process Creation
 2id: deb9b646-a508-44ee-b7c9-d8965921c6b6
 3related:
 4    - id: f3a98ce4-6164-4dd4-867c-4d83de7eca51
 5      type: similar
 6status: test
 7description: Detects TOKEN OBFUSCATION technique from Invoke-Obfuscation
 8references:
 9    - https://github.com/danielbohannon/Invoke-Obfuscation
10author: frack113
11date: 2022/12/27
12modified: 2022/12/30
13tags:
14    - attack.defense_evasion
15    - attack.t1027.009
16logsource:
17    category: process_creation
18    product: windows
19detection:
20    selection:
21        # Examples:
22        #   IN`V`o`Ke-eXp`ResSIOn (Ne`W-ob`ject Net.WebClient).DownloadString
23        #   &('In'+'voke-Expressi'+'o'+'n') (.('New-Ob'+'jec'+'t') Net.WebClient).DownloadString
24        #   &("{2}{3}{0}{4}{1}"-f 'e','Expression','I','nvok','-') (&("{0}{1}{2}"-f'N','ew-O','bject') Net.WebClient).DownloadString
25        #   ${e`Nv:pATh}
26        - CommandLine|re: '\w+`(\w+|-|.)`[\w+|\s]'
27        # - CommandLine|re: '\((\'(\w|-|\.)+\'\+)+\'(\w|-|\.)+\'\)' TODO: fixme
28        - CommandLine|re: '"(\{\d\})+"\s*-f'
29        - CommandLine|re: '\$\{((e|n|v)*`(e|n|v)*)+:path\}|\$\{((e|n|v)*`(e|n|v)*)+:((p|a|t|h)*`(p|a|t|h)*)+\}|\$\{env:((p|a|t|h)*`(p|a|t|h)*)+\}'
30    condition: selection
31falsepositives:
32    - Unknown
33level: high

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