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

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 one of the BadIIS native module DLLs used by UAT-8099. The actor deploys modules such as iis32.dll and iis64.dll to passively backdoor Internet-facing web servers. A worker process loading these attacker-specific DLLs indicates a malicious IIS module is active.

Reporting behind it

Related detections9 linkedT1505.004 — drag to rearrange

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Malicious BadIIS SEO Poisoning C2 Request via Web Server (via webserver)

Windows IIS module removal event (IIS-configuration EventID 29)

Windows IIS Configuration: Disable ETW Logging/Processing via logTargetW3C Change

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

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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