Alternate data streams (ADS) are a feature of the NTFS file system that allows storing additional data in a file without affecting its size, name, or functionality. ADS can be used to hide or embed data or executable code in a file, such as a specially crafted binary for later execution. ADS can be created or accessed using various tools or commands, such as the command prompt, PowerShell, or Sysinternals12. For example, the following command can create an ADS named secret.exe in a file named test.txt and run it using wmic.exe process call create function: type secret.exe > test.txt:secret.exe & wmic process call create "cmd.exe /c test.txt:secret.exe"