Change Default File Association Via Assoc

 1title: Change Default File Association Via Assoc
 2id: 3d3aa6cd-6272-44d6-8afc-7e88dfef7061
 3related:
 4    - id: ae6f14e6-14de-45b0-9f44-c0986f50dc89
 5      type: similar
 6status: test
 7description: |
 8    Detects file association changes using the builtin "assoc" command.
 9    When a file is opened, the default program used to open the file (also called the file association or handler) is checked. File association selections are stored in the Windows Registry and can be edited by users, administrators, or programs that have Registry access or by administrators using the built-in assoc utility. Applications can modify the file association for a given file extension to call an arbitrary program when a file with the given extension is opened.    
10references:
11    - https://github.com/redcanaryco/atomic-red-team/blob/f339e7da7d05f6057fdfcdd3742bfcf365fee2a9/atomics/T1546.001/T1546.001.md
12author: Timur Zinniatullin, oscd.community
13date: 2019/10/21
14modified: 2023/03/06
15tags:
16    - attack.persistence
17    - attack.t1546.001
18logsource:
19    category: process_creation
20    product: windows
21detection:
22    selection_img:
23        - Image|endswith: '\cmd.exe'
24        - OriginalFileName: 'Cmd.Exe'
25    selection_cli:
26        CommandLine|contains: 'assoc'
27    condition: all of selection_*
28fields:
29    - Image
30    - CommandLine
31    - User
32    - LogonGuid
33    - Hashes
34    - ParentProcessGuid
35    - ParentCommandLine
36falsepositives:
37    - Admin activity
38level: low