Malicious SharePoint ToolShell Post-Exploitation via Encoded PowerShell (via process_creation)

ATT&CK techniques

Initial Access → Execution

Recon
Resource Dev
Initial Access
- T1190Exploit Public-Facing Application
Execution
- T1059.001PowerShell
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects the SharePoint IIS worker process w3wp.exe spawning PowerShell with an encoded command argument. Following exploitation of the ToolShell vulnerabilities CVE-2025-49704 and CVE-2025-49706, attackers executed encoded PowerShell from the web service context to steal machine keys and deploy web shells. This parent child chain rarely occurs during normal SharePoint operation.

Reporting behind it

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Malicious SharePoint ToolShell Post-Exploitation via Encoded PowerShell (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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