How Do Rootkits Spread and How to Protect Against Rootkits?

Cybercriminals can install a rootkit on your computer in several ways. One of them is to exploit a vulnerability (a flaw in software or an operating system that has not been updated) and unwittingly install the rootkit on the computer. Another method relies on malicious links that can be sent by email or spread on social media as part of a phishing scam. Malware can also be bundled with other files, such as infected PDFs, pirated media, or third-party store apps.

When you are told not to trust strangers, it implies that you never open a link or document that a stranger sends you via email or chat. Never install a "special plugin" (supposedly legitimate) to view a web page or open a file.

Unlike viruses and worms, rootkits do not propagate or self-replicate. In general, rootkits are just one component of a combined threat based on 3 snippets (a small reusable portion of code): the dropper, the loader, and the rootkit.

Here's How They Work:

Activating the dropper generally requires human intervention, such as clicking on a malicious link, which launches the loader. The dropper deletes itself while the loader causes a buffer overflow/overflow (when there is more data than allocated space). This loads the rootkit into the computer's memory, creating a backdoor that allows cybercriminals to modify system files so that they are not detected by the user or by basic antivirus software.

They then have remote access to the operating system and can use the infiltrated computer to send spam, launch large-scale pharming or denial of service (DDoS) attacks, or steal sensitive data.

Types of Rootkits

Some rootkits can be stubborn, others not. Stubborn rootkits can activate on their own every time you start your computer. Those that are not tenacious settle in memory and die when restarting the computer.

A rootkit can be identified by the affected area of ​​the system and how it hides.

1. Kernel Mode Rootkits: These operate within the operating system kernel and frequently cause system bugs. This is often the element that allows Microsoft Support to determine if the device is infected with a rootkit. The attacker first exploits the system by loading malware into the kernel, which then intercepts system calls or adds its own data, filtering out any data that might make it visible. Kernel-mode malware can be used to cover trails and hide threats in both the kernel and user-mode components. Petty!
2. Rootkits in user mode: either they are launched as a program at system startup, or they are injected into the system by a dropper. They have functionality similar to kernel-mode rootkits (hiding and disabling access to files) but operate at the user level. They are not as stealthy but their ease of implementation explains their expansion. They are popular for financial malware. Carberp, one of the most copied strains of financial malware, was designed to steal bank credentials and sensitive data from users. So beware of invoice type spam or payment reminders!
3. Hybrid rootkits: they have the characteristics of both modes (user and kernel). This approach is one of the most popular among hackers because it has a high penetration success rate in computers.
4. Bootloaders: They target the basic components of the computer by infecting the Master Boot Record (MBR), a fundamental sector that instructs the computer to load the operating system.
5. Firmware Rootkits: They can hide in firmware (such as a CPU or router) when the computer shuts down. When the computer restarts, they then reinstall themselves.
6. Rootkits installed in a virtual machine (VMBR): they transport the operating system in a virtual environment in order to prevent or complicate their detection. They load under the existing operating system and then run it as a virtual machine. VMBRs can thus go unnoticed unless special software has been trained to detect them. It's always the same principle.

How to Protect Yourself Against Rootkits

Rootkits are sneaky and insidious, but there are a number of ways you can escape them. Many strategies to avoid rootkits can also protect you against all types of threats:

• Don't open email attachments from unknown senders 
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• Don't download files whose content you don't know
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• Make sure your system is up to date and has patches for known vulnerabilities
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• Install your software carefully, make sure it is legitimate, and the End User License Agreement (EULA) is normal
• Use external drives and USB drives with care

In addition to following these common-sense rules, you can strengthen your defense against rootkits by installing a powerful antivirus. Some antiviruses aren't always enough to detect them, but Protegent360's Free Antivirus Software detects and removes the most insidious and hidden rootkits, for the modest sum of zero dollars.