UMWorkerProcess Creating Webshell
This query detects unusual file content created by UMWorkerProcess, indicating exploitation of CVE-2021-26858 to generate a web shell. More related queries can be found on the Microsoft Security Response Center blog.
Detection logic
Detection requirements
- Log source product
- microsoftthreatprotection
- Log source service
- devicefileevents
MITRE ATT&CK mappings
Not mapped to ATT&CK.
No references are available for this detection.
From the source
- At source
- Open at source
- Upstream identifier
- 60d15bd4-1fad-4a70-bc3b-094dc1c5e554
- Tagged by the source as
- ExecutionExploitPersistence
Licence
- Published under
- MIT LicenseRead the licence
- Attribution
- Required
- Obtained under
- MITRead the origin licence
Authorship
- Published
- Sep 1, 2026
- Version
- 1