Sigma rule: Change Default File Association To Executable Via Assoc

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-dda7b8f84b81, updated 2023-03-06T00:00:00.000Z.

Rule

Title
Change Default File Association To Executable Via Assoc
Status
test
Level
high
Author
Nasreddine Bencherchali (Nextron Systems)
Date
2022-06-28
Modified
2023-03-06
File
rules/windows/process_creation/proc_creation_win_cmd_assoc_tamper_exe_file_association.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

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.

Log source

product
windows
category
process_creation

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 filter

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.privilege-escalation
  • attack.persistence
  • attack.t1546.001

MITRE ATT&CK ids this rule names

Related rules

References

Read on 2026-11-03T00:58:21.399Z under licence sigma-drl-1.1@d5f4c36a from https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_cmd_assoc_tamper_exe_file_association.yml

Sources and licences

  • SigmaHQ

    "Change Default File Association To Executable Via Assoc" by Nasreddine Bencherchali (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_cmd_assoc_tamper_exe_file_association.yml.
    Licensed under the Detection Rule License (DRL) 1.1: https://github.com/SigmaHQ/Detection-Rule-License

    Detection Rule License (DRL) 1.1

Cite this page

Dragons Eye Ransomware Tracker, "Sigma rule: Change Default File Association To Executable Via Assoc",
entity page, dataset version ref-dda7b8f84b81, updated 2023-03-06T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/ae6f14e6-14de-45b0-9f44-c0986f50dc89 (accessed 2026-11-03).
Underlying source: SigmaHQ rule ae6f14e6-14de-45b0-9f44-c0986f50dc89, commit ccbb0369507f796db0b0ae6854c8a2be471b9d84.

Pages change. The dataset version identifies the data, but no archive of old versions is kept, so this citation cannot be replayed later.