Change Default File Association To Executable Via Assoc
Detects when a program changes the default file association of any extension to an executable. 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.
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Open this Sigma rule in the converter with the YAML preloaded and ready for backend selection.
Events generated when a new process is spawned on the system. Covers command-line arguments, parent/child relationships, and process metadata.
detection:
selection_img:
- Image|endswith: '\cmd.exe'
- OriginalFileName: 'Cmd.Exe'
selection_cli:
CommandLine|contains|all:
- 'assoc '
- 'exefile'
filter:
CommandLine|contains: '.exe=exefile'
condition: all of selection_* and not filterFalse positive likelihood has not been assessed. Additional context may be needed during triage.