Windows File Download Via PowerShell — Detection Rule
The following analytic detects the use of PowerShell's download methods such as "DownloadString" and "DownloadData" from the WebClient class or Invoke-WebRequest and it's aliases "IWR" or "Curl". It leverages data from Endpoint Detection and Response (EDR) agents, focusing on process execution logs that include command-line details. This activity can be significant such methods and functions are commonly used in malicious PowerShell scripts to fetch and execute remote code. If confirmed malicious, this behavior could allow an attacker to download and run arbitrary code, potentially leading to unauthorized access, data exfiltration, or further compromise of the affected system.