Malicious Office Persistence via WLL Add-In Dropped to Word STARTUP Folder
- Product
- windows
- Category
- file_event
- Author
- HuntRule
- Published
- 2026-10-15
- Updated
- 2026-10-15
ATT&CK techniques
PersistenceRecon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact
What it detects
This rule detects creation of a Word add-in library file in the Microsoft Word STARTUP folder which the Sisfader RAT uses for persistence after CVE-2017-8570 exploitation. Observed in NCC Group research on CVE-2017-8570 RTF documents delivering the Sisfader RAT via an SCT to WLL chain. WLL add-ins auto-load with Word which makes this a reliable persistence detection.
Reporting behind it
Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.
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