Windows Exfiltration Over C2 Via Powershell UploadString

The following analytic identifies potential data exfiltration using the PowerShell `net.webclient` command with the `UploadString` method. It leverages PowerShell Script Block Logging to detect instances where this command is executed. This activity is significant as it may indicate an attempt to upload sensitive data, such as desktop screenshots or files, to an external or internal URI, often associated with malware like Winter-Vivern. If confirmed malicious, this could lead to unauthorized data transfer, compromising sensitive information and potentially leading to further exploitation of the compromised host.

ATT&CK coverage

Exfiltration

T1041Exfiltration Over C2 Channel 30 detections cover this technique

Detection requirements

Log source category: powershell_script_block_logging_4104

Detection logic

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Detection catalogue

ATT&CK coverage

Detection requirements

Detection logic