Malicious BADIIS Native IIS Module Loaded by Worker Process (via image_load)

ATT&CK techniques

Persistence

Recon
Resource Dev
Initial Access
Execution
Persistence
- T1505.004IIS Components
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects the IIS worker process loading the BADIIS native module DLL registered under the default application pool for SEO poisoning. Observed in Elastic Security Labs analysis where WsmRes64.dll is loaded by w3wp.exe to intercept and manipulate web traffic as a malicious IIS component.

Reporting behind it

Related detections9 linkedT1505.004 — drag to rearrange

Malicious BadIIS C2 Communication via lwxatisme User-Agent

Suspicious BadIIS Native Module Registration via cmd Copy

Malicious Native IIS Module Installation via Appcmd by UAT-8099

Malicious BadIIS Module Load into IIS Worker Process by UAT-8099

Suspicious Malicious IIS Module DLL Written to Inetsrv Directory (via file_event)

Malicious Webserver IIS Configuration Edited - SYSMON (via file_event)

Malicious Webserver IIS Module Installed - Command (via process_creation)

Malicious Webserver IIS Module Installed - Command (via process_creation) - Variant 2

Malicious Webserver IIS Module Installed - PowerShell (via powershell)

Malicious BADIIS Native IIS Module Loaded by Worker Process (via image_load)

Pivot detection · T1505.004 · 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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