Suspicious PowerShell WebClient Download of Executable Payload

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 instantiating a dotnet WebClient object and invoking DownloadFile to retrieve a payload which the Dagon Locker intrusion used to pull a follow on DLL from a public file sharing host and this matters because the WebClient DownloadFile pattern is a widely abused fileless download primitive that fetches second stage tooling onto the host.

Reporting behind it

Related detections9 linkedT1059.001 — drag to rearrange

Suspicious PowerShell Download of Disguised Payload to ProgramData

Suspicious PowerShell Remote Script Execution via IEX DownloadString

Suspicious PowerShell Download Cradle to Blogspot (via process_creation)

Suspicious Hidden PowerShell WebClient DownloadFile Cradle

Suspicious PowerShell Download Cradle with Spoofed User-Agent via MSIX

Malicious PowerShell In-Memory Download Cradle via Script Block (via ps_script)

Suspicious node.exe Execution Spawned by PowerShell

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

Suspicious PowerShell Download to Temp and In-Memory Execution via IEX (via process_creation)

Suspicious PowerShell WebClient Download of Executable Payload

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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