Suspicious PowerShell UTF8 OutputEncoding Command Wrapper

PremiumReviewedSigma · Medium · v1
Product
windows
Category
process_creation
Author
HuntRule
Published
2026-09-22
Updated
2026-09-22

ATT&CK techniques

Execution
  1. Recon

  2. Resource Dev

  3. Initial Access

  4. Persistence

  5. Priv Esc

  6. Defense Evasion

  7. Cred Access

  8. Discovery

  9. Lateral Movement

  10. Collection

  11. C2

  12. Exfiltration

  13. Impact

What it detects

This rule detects PowerShell command lines that set OutputEncoding to a UTF8 encoding object before running an inline command, the wrapper ChaosBot used for every shell command it executed. The Rust bot prefixed all remote commands with this OutputEncoding assignment to reliably capture and exfiltrate output over Discord. While some scripts set encoding, this exact inline pattern combined with remote command execution is suspicious.

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Suspicious PowerShell UTF8 OutputEncoding Command Wrapper
Pivot detection · T1059.001 · 9 related

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