Possible PowerShell Hidden Download Cradle via Process Creation

ATT&CK techniques

Execution → C2

Recon
Resource Dev
Initial Access
Execution
- T1059.001PowerShell
Persistence
Priv Esc
Defense Evasion
Cred Access
Discovery
Lateral Movement
Collection
C2
- T1105Ingress Tool Transfer
Exfiltration
Impact

What it detects

This rule detects PowerShell launched with hidden window and no-profile flags executing an in-memory download cradle that uses Net.WebClient DownloadString. Observed in NCC Group research on TA505 exploiting the SolarWinds Serv-U vulnerability CVE-2021-35211 for initial access. This technique stages remote payloads directly in memory to evade disk-based detection which makes it a high-value indicator.

Reporting behind it

Related detections9 linkedT1059.001 — drag to rearrange

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Suspicious Hidden PowerShell Download and Archive Expansion

Malicious PowerShell IEX DownloadString One-Liner

Malicious Cloud Atlas PowerShell Download Cradle via IEX WebClient (via process_creation)

Suspicious PowerShell Downloader Spawned by Batch Script (via process_creation)

Suspicious Curl Download and Script Execution Chain via Command Line

Possible PowerShell Hidden Download Cradle 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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