Suspicious Remote Script Download and Execution via iwr Piped to iex

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 using Invoke-WebRequest piped into Invoke-Expression to download and run an install script in memory, observed in a Huntress Komari intrusion that fetched install.ps1 to deploy the agent. The iwr into iex pattern executes remote code without writing the script to disk. This download-cradle technique is a common precursor to agent and tooling deployment.

Reporting behind it

Related detections9 linkedT1059.001 — drag to rearrange

Malicious ActiveMQ Exploitation Java Spawning PowerShell Downloader (via process_creation)

Malicious In-Memory Payload Execution via PowerShell DownloadString (via process_creation)

Suspicious PowerShell Invoke-WebRequest Download of Executable Payload

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

Suspicious PowerShell Download of scrss or ekrn Masquerading Scripts

Suspicious Remote Script Download and Execution via iwr Piped to iex

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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