T1547.006: Kernel Modules and Extensions
| View on MITRE ATT&CK | T1547.006 |
|---|---|
| Tactic(s) | Privilege Escalation, Persistence |
| Associated CAPEC Patterns | Install Rootkit (CAPEC-552) |
Data from MITRE ATT&CK®:
Adversaries may modify the kernel to automatically execute programs on system boot. Loadable Kernel Modules (LKMs) are pieces of code that can be loaded and unloaded into the kernel upon demand. They extend the functionality of the kernel without the need to reboot the system. For example, one type of module is the device driver, which allows the kernel to access hardware connected to the system.(Citation: Linux Kernel Programming)
When used maliciously, LKMs can be a type of kernel-mode Rootkit that run with the highest operating system privilege (Ring 0).(Citation: Linux Kernel Module Programming Guide) Common features of LKM based rootkits include: hiding itself, selective hiding of files, processes and network activity, as well as log tampering, providing authenticated backdoors, and enabling root access to non-privileged users.(Citation: iDefense Rootkit Overview)
Kernel extensions, also called kext, are used in macOS to load functionality onto a system similar to LKMs for Linux. Since the kernel is responsible for enforcing security and the kernel extensions run as apart of the kernel, kexts are not governed by macOS security policies. Kexts are loaded and unloaded through kextload and kextunload commands. Kexts need to be signed with a developer ID that is granted privileges by Apple allowing it to sign Kernel extensions. Developers without these privileges may still sign kexts but they will not load unless SIP is disabled. If SIP is enabled, the kext signature is verified before being added to the AuxKC.(Citation: System and kernel extensions in macOS)
Since macOS Catalina 10.15, kernel extensions have been deprecated in favor of System Extensions. However, kexts are still allowed as "Legacy System Extensions" since there is no System Extension for Kernel Programming Interfaces.(Citation: Apple Kernel Extension Deprecation)
Adversaries can use LKMs and kexts to conduct Persistence and/or Privilege Escalation on a system. Examples have been found in the wild, and there are some relevant open source projects as well.(Citation: Volatility Phalanx2)(Citation: CrowdStrike Linux Rootkit)(Citation: GitHub Reptile)(Citation: GitHub Diamorphine)(Citation: RSAC 2015 San Francisco Patrick Wardle)(Citation: Synack Secure Kernel Extension Broken)(Citation: Securelist Ventir)(Citation: Trend Micro Skidmap)
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Cyber Threat Graph Context
Explore how this ATT&CK Technique relates to the wider threat graph
Mitigations for this technique
MITRE ATT&CK Mitigations
Antivirus/Antimalware
Use signatures or heuristics to detect malicious software.Privileged Account Management
Manage the creation, modification, use, and permissions associated to privileged accounts, including SYSTEM and root.User Account Management
Manage the creation, modification, use, and permissions associated to user accounts.Execution Prevention
Block execution of code on a system through application control, and/or script blocking.How to detect this technique
MITRE ATT&CK Data Components
Kernel Module Load (Kernel)
An object file that contains code to extend the running kernel of an OS, typically used to add support for new hardware (as device drivers) and/or filesystems, or for adding system callsProcess Creation (Process)
The initial construction of an executable managed by the OS, that may involve one or more tasks or threads. (e.g. Win EID 4688, Sysmon EID 1, cmd.exe > net use, etc.)Command Execution (Command)
The execution of a line of text, potentially with arguments, created from program code (e.g. a cmdlet executed via powershell.exe, interactive commands like >dir, shell executions, etc. )File Modification (File)
Changes made to a file, or its access permissions and attributes, typically to alter the contents of the targeted file (ex: Windows EID 4670 or Sysmon EID 2)File Creation (File)
Initial construction of a new file (ex: Sysmon EID 11)Control Validation Tests for this Technique
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Sigma Detections for this Technique
SP800-53 Controls
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