Suspicious OpenWith Process Spawned by Script Host for Code Injection (via process_creation)

PremiumReviewedSigma · High · v1
Product
windows
Category
process_creation
Author
HuntRule
Published
2026-10-22
Updated
2026-10-22

ATT&CK techniques

Priv Esc → Defense Evasion
  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Execution

  5. Persistence

  6. Cred Access

  7. Discovery

  8. Lateral Movement

  9. Collection

  10. C2

  11. Exfiltration

  12. Impact

What it detects

This rule detects OpenWith.exe launched by PowerShell or MSBuild, an unusual parentage abused by Amatera Stealer as an Early Bird injection target. The stealer started OpenWith in a suspended state and hijacked its thread context to run shellcode.

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Detection content is published as a reviewed draft. Tune thresholds and exclusions against your own telemetry before enabling this rule for alerting.