What are Rootkits? Discovering one of the most insidious threats

Sandro Sana : 3 August 2025 11:16

Rootkits are one of the most insidious and complex cyber threats in the digital security landscape. The term “rootkit” comes from the combination of two words: “root,” which in Unix and Linux systems refers to the user with the highest privileges, and “kit,” which indicates a set of software tools. A rootkit, therefore, is a set of tools designed to grant privileged access to a computer system while remaining hidden from the user and security software.

How Do Rootkits Work?

Rootkits work by infiltrating the operating system or other core software components, masking their presence and allowing an attacker to maintain control of the system for an extended period. This ability to operate in the shadows is what makes rootkits particularly dangerous. They can be used to:

1. Steal sensitive data: such as personal information, login credentials, and financial data.
2. Install other types of malware: acting as a “front door” for other malicious software such as Trojans, viruses, and spyware.
3. Compromise system integrity: manipulating system files, processes, and registries so that rootkit activity goes undetected.

Levels of Infiltration

Rootkits can operate at different levels of the system:

• User Level: They interact with user applications and processes and are easier to detect and remove than other types.
• Kernel Level: They operate at the kernel level of the operating system, which is the central core that manages the computer’s resources. These rootkits are particularly dangerous because they have complete control over the system.
• Boot Level: They attack the system during the boot phase, before the operating system even loads. They are among the most difficult to detect and remove.

Difference Between Rootkits and Other Types of Malware

To fully understand what distinguishes rootkits from other malware, it’s helpful to compare them to other types of malicious software:

• Viruses: Viruses spread by replicating themselves in other programs or files. They can damage data, slow down system performance, or cause malfunctions, but they generally don’t try to hide their presence like rootkits do.
• Trojan: Trojans (or Trojan horses) pose as legitimate software but hide malicious functionality. Like rootkits, they can provide remote access to the system, but they don’t necessarily try to keep this access hidden over time.
• Worms: Worms are malware that spread autonomously through computer networks, without needing to attack specific files. While they can compromise system security, they are not designed to hide their system-level activity like rootkits.
• Spyware: This type of malware is designed to spy on user activity, collecting data without their consent. Although it often operates covertly, its primary purpose is information gathering rather than persistent system control.

The main difference between a rootkit and other types of malware is its ability to hide its presence and ensure continuous and invisible access to the system, often at the kernel or boot level. This makes it extremely difficult to detect and remove compared to other types of malware, which are more easily identified through antivirus scans or system behavior detection.

Conclusions

Rootkits represent one of the most advanced and subtle threats in the field of cybersecurity. Their ability to remain hidden while granting privileged access to the system makes them particularly dangerous. Defending against rootkits requires advanced detection tools and a thorough understanding of operating system dynamics. For this reason, it is essential that organizations and home users adopt rigorous security practices, keeping their systems updated and using advanced protection software to minimize the risk of infection.

Sandro Sana
Member of the Red Hot Cyber Dark Lab team and director of the Red Hot Cyber Podcast. He has worked in Information Technology since 1990 and specialized in Cybersecurity since 2014 (CEH - CIH - CISSP - CSIRT Manager - CTI Expert). Speaker at SMAU 2017 and SMAU 2018, lecturer for SMAU Academy & ITS, and member of ISACA. He is also a member of the Scientific Committee of the national Competence Center Cyber 4.0, where he contributes to the strategic direction of research, training, and innovation activities in the cybersecurity.

Lista degli articoli
Visita il sito web dell'autore