Malicious PowerShell Spawned by IIS Worker Process via OWASSRF Exchange Exploitation (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 IIS worker process w3wp.exe spawning PowerShell, a post-exploitation pattern seen in the OWASSRF exploitation of Exchange CVE-2022-41080 and CVE-2022-41082 through Outlook Web Access. Attackers use this server-side execution to run reconnaissance and drop tooling after bypassing ProxyNotShell mitigations, so PowerShell descended from an Exchange web process is a strong compromise signal.

Reporting behind it

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Malicious PowerShell Spawned by IIS Worker Process via OWASSRF Exchange Exploitation (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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