Suspicious PowerShell IEX DownloadString In-Memory Execution via process_creation

ATT&CK techniques

Execution

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

What it detects

This rule detects PowerShell that combines Invoke-Expression with the WebClient DownloadString method to fetch and run remote code entirely in memory. Head Mare and Twelve launched PowerShell with an execution policy bypass and hidden window to download and execute scripts including ADRecon. This fileless download and execute pattern is a common intrusion loader technique.

Reporting behind it

Related detections9 linkedT1059.001 — drag to rearrange

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Suspicious PowerShell Download Cradle via IEX and DownloadString (via process_creation)

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Suspicious PowerShell IEX DownloadString In-Memory Execution 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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