SharePoint IIS Worker Process Spawning PowerShell With Encoded Command (via process_creation)

ATT&CK techniques

Execution → Persistence

Recon
Resource Dev
Initial Access
Execution
- T1059.001PowerShell
Persistence
- T1505.003Web Shell
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects the IIS worker process w3wp.exe spawning PowerShell that runs an encoded command, the post-exploitation behavior seen after ToolShell CVE-2025-53770 exploitation of SharePoint. Adversaries leverage a deployed webshell to launch encoded PowerShell that extracts machine keys, making this chain a strong early indicator of server-side code execution.

Reporting behind it

Related detections9 linkedT1059.001 — drag to rearrange

Suspicious IIS Worker Process Spawning Command or Scripting Interpreter via SharePoint ToolShell Exploitation (via process_creation)

Malicious IIS Worker Process Spawning Command Shell for Webshell Reconnaissance (via process_creation)

Malicious IIS w3wp Worker Spawning Command Interpreter via SharePoint Web Shell

Malicious IIS Worker Process Spawning PowerShell via Gladinet CentreStack Exploit

Exchange Worker Process Spawning Command Shell via OWASSRF

Malicious Exchange or SharePoint Worker Process Spawning Command Shell from Web Shell (via process_creation)

ClickFix PowerShell Download Cradle Launched From Run Dialog (via process_creation)

In-Memory Phantom Stealer In-Memory Process Injection via PowerShell Add-Type API Chain (via ps_script)

PowerShell Hidden DownloadString Execution via ClickFix Fake CAPTCHA (via process_creation)

SharePoint IIS Worker Process Spawning PowerShell With Encoded Command (via process_creation)

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.

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