Sunturai
Back to results
MediumSplunk security contentMichael Haag +1

Powershell Fileless Script Contains Base64 Encoded Content

The following analytic detects the execution of PowerShell scripts containing Base64 encoded content, specifically identifying the use of `FromBase64String`. It leverages PowerShell Script Block Logging…

Description

The following analytic detects the execution of PowerShell scripts containing Base64 encoded content, specifically identifying the use of `FromBase64String`. It leverages PowerShell Script Block Logging (EventCode=4104) to capture and analyze the full command sent to PowerShell. This activity is significant as Base64 encoding is often used by attackers to obfuscate malicious payloads, making it harder to detect. If confirmed malicious, this could lead to code execution, allowing attackers to run arbitrary commands and potentially compromise the system.

Detection logic

Detection requirements

Platform
ESXiLinuxmacOSNetwork DevicesWindows

The rule states no platform. This is derived from the 2 ATT&CK techniques it maps to.

Log source category
powershell_script_block_logging_4104

Known benign triggers

  • False positives should be limited. Filter as needed.

Detections can measure how the public catalogue is used — which detections people look for, and which pages bring them here. It sets a cookie that recognises this browser for 180 days. It is never linked to an account and never follows you to other sites. Privacy notice