Sigma rule: Uncommon FileSystem Load Attempt By Format.com

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-3c2f9d343113, updated 2024-05-13T00:00:00.000Z.

Rule

Title
Uncommon FileSystem Load Attempt By Format.com
Status
test
Level
high
Author
Florian Roth (Nextron Systems)
Date
2022-01-04
Modified
2024-05-13
File
rules/windows/process_creation/proc_creation_win_format_uncommon_filesystem_load.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects the execution of format.com with an uncommon filesystem selection that could indicate a defense evasion activity in which "format.com" is used to load malicious DLL files or other programs.

Log source

product
windows
category
process_creation

Detection

selection:
    Image|endswith: '\format.com'
    CommandLine|contains: '/fs:'
filter_main_known_fs:
    CommandLine|contains:
        - '/fs:exFAT'
        - '/fs:FAT'
        - '/fs:NTFS'
        - '/fs:ReFS'
        - '/fs:UDF'
condition: selection and not 1 of filter_main_*

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.stealth

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_format_uncommon_filesystem_load.yml

Sources and licences

  • SigmaHQ

    "Uncommon FileSystem Load Attempt By Format.com" by Florian Roth (Nextron Systems) (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules/windows/process_creation/proc_creation_win_format_uncommon_filesystem_load.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: Uncommon FileSystem Load Attempt By Format.com",
entity page, dataset version ref-3c2f9d343113, updated 2024-05-13T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/9fb6b26e-7f9e-4517-a48b-8cac4a1b6c60 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 9fb6b26e-7f9e-4517-a48b-8cac4a1b6c60, 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.