value: Adversaries may use rootkits to hide the presence of programs, files, network connections, services, drivers, and other system components. Rootkits are programs that hide the existence of malware by intercepting/hooking and modifying operating system API calls that supply system information. (Citation: Symantec Windows Rootkits) 
  
  Rootkits or rootkit enabling functionality may reside at the user or kernel level in the operating system or lower, to include a hypervisor, Master Boot Record, or [System Firmware](T1542.001). (Citation: Wikipedia Rootkit) Rootkits have been seen for Windows, Linux, and Mac OS X systems. (Citation: CrowdStrike Linux Rootkit) (Citation: BlackHat Mac OSX Rootkit)
name: Rootkit