Rootkits can be categorized into several types based on their characteristics, behavior, and the level of access they have to the compromised system. Here are the main types of rootkits:
- User-mode Rootkits:
- These rootkits operate at the user level of the operating system.
- They typically modify system binaries, libraries, or configuration files to hide their presence and activities.
- User-mode rootkits are relatively easier to detect compared to kernel-mode rootkits but can still be challenging to remove completely.
- Examples include:
- DLL (Dynamic Link Library) injection rootkits: Inject malicious code into legitimate system DLLs to manipulate system behavior.
- Application-level rootkits: Modify user-level applications to hide malicious activities.
- Kernel-mode Rootkits:
- Kernel-mode rootkits operate at a deeper level within the operating system, directly interacting with the kernel.
- They have higher privileges and greater control over system resources, making them more difficult to detect and remove.
- Kernel-mode rootkits often intercept system calls, manipulate kernel data structures, or modify kernel code to conceal their presence and actions.
- Examples include:
- Direct kernel object manipulation rootkits: Modify kernel data structures, such as process lists or file system structures, to hide processes or files associated with the rootkit.
- Kernel API hooking rootkits: Intercept system calls made by user-level applications and redirect them to malicious code.
- Kernel driver rootkits: Install malicious device drivers that manipulate system behavior at the kernel level.
- Bootkits:
- Bootkits infect the boot process of a computer, allowing them to execute before the operating system loads.
- They replace or modify bootloader components, such as the Master Boot Record (MBR) or boot sector, to gain control over the system.
- Bootkits have the highest level of privilege and persistence, as they can subvert security measures implemented by the operating system.
- Examples include:
- MBR rootkits: Infect the Master Boot Record of a disk to execute malicious code during the boot process.
- Unified Extensible Firmware Interface (UEFI) rootkits: Infect the UEFI firmware of the system motherboard to execute before the operating system loads.
- Hardware or Firmware Rootkits:
- These rootkits target system firmware or hardware components, making them extremely difficult to detect and remove.
- Hardware or firmware rootkits can manipulate the behavior of hardware devices or compromise system firmware, such as BIOS or UEFI.
- Due to their low-level nature, they can persist even if the operating system is reinstalled or replaced.
- Examples include:
- BIOS/UEFI rootkits: Infect the system firmware (BIOS or UEFI) to execute malicious code before the operating system loads.
- Peripheral rootkits: Compromise firmware on peripheral devices, such as network interface cards or USB controllers, to intercept data or execute malicious code.
Each type of rootkit poses unique challenges for detection and removal, requiring specialized tools and techniques to effectively mitigate their impact on system security.
