Sigma rule: Suspicious Word Cab File Write CVE-2021-40444

A detection rule from the SigmaHQ repository, shown as its author published it. Dataset version ref-26c56730f58c, updated 2023-06-22T00:00:00.000Z.

Rule

Title
Suspicious Word Cab File Write CVE-2021-40444
Status
test
Level
high
Author
Florian Roth (Nextron Systems), Sittikorn S
Date
2021-09-10
Modified
2023-06-22
File
rules-emerging-threats/2021/Exploits/CVE-2021-40444/file_event_win_exploit_cve_2021_40444.yml
Commit
ccbb0369507f796db0b0ae6854c8a2be471b9d84

Detects file creation patterns noticeable during the exploitation of CVE-2021-40444

Log source

product
windows
category
file_event

Detection

selection_cab:
    Image|endswith: '\winword.exe'
    TargetFilename|contains: '\Windows\INetCache'
    TargetFilename|endswith: '.cab'
selection_inf:
    Image|endswith: '\winword.exe'
    TargetFilename|contains|all:
        - '\AppData\Local\Temp\'
        - '.inf'
filter_main_legit:
    TargetFilename|startswith: 'C:\Users\'
    TargetFilename|contains: 'AppData\Local\Temp'
    TargetFilename|endswith: '\Content.inf'
condition: 1 of selection_* and not 1 of filter_main_*

False positives (as the rule lists them)

  • Unknown

Tags

  • attack.resource-development
  • attack.t1587
  • detection.emerging-threats

MITRE ATT&CK ids this rule names

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-emerging-threats/2021/Exploits/CVE-2021-40444/file_event_win_exploit_cve_2021_40444.yml

Sources and licences

  • SigmaHQ

    "Suspicious Word Cab File Write CVE-2021-40444" by Florian Roth (Nextron Systems), Sittikorn S (SigmaHQ). Rule: https://github.com/SigmaHQ/sigma/blob/ccbb0369507f796db0b0ae6854c8a2be471b9d84/rules-emerging-threats/2021/Exploits/CVE-2021-40444/file_event_win_exploit_cve_2021_40444.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: Suspicious Word Cab File Write CVE-2021-40444",
entity page, dataset version ref-26c56730f58c, updated 2023-06-22T00:00:00.000Z,
https://ransomware-tracker.com/detections/sigma/60c0a111-787a-4e8a-9262-ee485f3ef9d5 (accessed 2026-11-03).
Underlying source: SigmaHQ rule 60c0a111-787a-4e8a-9262-ee485f3ef9d5, 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.