Process Creation With Double File Extension

calendar Jan 30, 2023 · attack.defense_evasion attack.t1036 attack.t1036.007  ·
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Detects process creation utilizing double file extensions, a common method of masquerading or obfuscating a file type in malware delivery. Observed in early 2023 AsyncRAT/Quasar malware delivery using malicious OneNote files.

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 1title: Process Creation With Double File Extension
 2id: dd980d89-f015-4d55-b762-ef200843308c
 3status: experimental
 4description: Detects process creation utilizing double file extensions, a common method of masquerading or obfuscating a file type in malware delivery. Observed in early 2023 AsyncRAT/Quasar malware delivery using malicious OneNote files.
 5references:
 6    - https://www.pcmag.com/encyclopedia/term/double-extension
 7    - Original research by Micah Babinski
 8author: Micah Babinski, @micahbabinski
 9date: 2023/01/30
10tags:
11    - attack.defense_evasion
12    - attack.t1036
13    - attack.t1036.007
14logsource:
15    category: process_creation
16    product: windows
17detection:
18    selection1:
19        ParentImage|re: ^.*\\[a-zA-Z0-9]*\.[a-zA-Z0-9]*\.[a-zA-Z0-9]*$
20    selection2:
21        Image|re: ^.*\\[a-zA-Z0-9]*\.[a-zA-Z0-9]*\.[a-zA-Z0-9]*$
22    condition: selection1 or selection2
23falsepositives:
24    - Unknown
25level: high```

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