Suspicious RegAsm Execution Spawned by Script Host for Process Hollowing (via process_creation)

ATT&CK techniques

Priv Esc → Defense Evasion

Recon
Resource Dev
Initial Access
Execution
Persistence
Priv Esc
- T1055.012Process Hollowing
Defense Evasion
- T1055.012Process Hollowing
Cred Access
Discovery
Lateral Movement
Collection
C2
Exfiltration
Impact

What it detects

This rule detects the .NET RegAsm utility being launched by a script host or PowerShell, a pattern used by AsyncRAT to hollow the trusted RegAsm.exe process with the NewPE2 injector. RegAsm is a developer registration tool and is not normally started by wscript, cscript, mshta or powershell. This parent-child relationship exposes the injection target used to run the final RAT payload.

Reporting behind it

Related detections9 linkedT1055.012 — drag to rearrange

Suspicious .NET Utility Launched as Process Injection Target (via process_creation)

Suspicious RegAsm Spawned as Process Hollowing Target

Suspicious SearchIndexer Process Started by Non-Service Parent for Hollowing

Suspicious Browser Updater Binary Spawned by AutoIt for Process Hollowing

Suspicious DotNet Utility Spawned by Script Host for Process Hollowing via Command Line

Suspicious Outbound Network Connection from msiexec.exe (via network_connection)

Suspicious Outbound Connection from tracerpt.exe after Process Hollowing (via network_connection)

Suspicious AddInProcess32 Outbound Connection after Process Hollowing

Suspicious microsoftedgeupdatecore Outbound Connection from Wrong Path

Suspicious RegAsm Execution Spawned by Script Host for Process Hollowing (via process_creation)

Pivot detection · T1055.012 · 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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