Suspicious DotNet Utility MSBuild RegAsm RegSvcs Network Beacon Indicating Hollowing

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 MSBuild.exe, RegAsm.exe or RegSvcs.exe making an external network connection, the process hollowing targets used by Blind Eagle to run Remcos and njRAT with command and control over dynamic DNS. These .NET utilities have no reason to beacon outbound, so an external connection reveals injected remote access malware.

Reporting behind it

Related detections9 linkedT1055.012 — drag to rearrange

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 or AppLaunch Outbound Connection after Injection

Suspicious SearchProtocolHost Network Connection Indicating Process Hollowing

Suspicious Network Connection from fsutil or Defender Client via network_connection

Suspicious Execution of Dotnet Injection Target Utilities

Suspicious DotNet Utility MSBuild RegAsm RegSvcs Network Beacon Indicating Hollowing

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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