How Does a Rootkit Work?
Rootkit is a complex malware that contains a series of complex tools and bots that infect computers and digital networks in different stages using different channels. The name “Rootkit” has two parts in which root signifies the most privileged admin and the kit is the applications that facilitate unauthorized root or admin-level access. Hackers use a wide range of means and methods including phishing emails, attachments, spoofed links, DDoS, and social engineering attacks to distribute rootkits on a target device.
When a user opens phishing emails, accesses the attachment, or clicks the malicious link the rootkits move in their system. The DDoS attacks overwhelm critical processes and render the device unusable to the user. Once the malware is inside the device it can remain hidden in the system for a long time and actively runs its malicious operations. It modifies system files, changes security settings, and bypasses normal access controls. Most importantly, it creates a backdoor entry for the cybercriminals into the machine that allows them to take full control of it remotely.
Hackers use rootkits to spy on user activities and steal important information such as banking and credit card details, important passwords, keystroke loggers, and other sensitive data. They use compromised devices to create more botnets to target other devices and launch more cyber attacks.
What are the Different Types of Rootkits?
There are different types of ‘Rootkits’ that are categorized on their level of operations and where they are installed within a system. The following are the main types of rootkits:
Kernel-Level Rootkits
Kernel-level rootkits are one of the most dangerous rootkits. They integrate with the core part of the operating system that manages hardware and software interactions. The deep integration makes the detection and removal of these malicious software highly difficult. When in the system It operates at the highest privilege level. It can hide files, processes, or network connections and modify kernel data structures and system calls.
Adore is the best example of a Linux-based kernel-level rootkit. It became famous in the 2000s for its ability to remain hidden and inactive in the system. It hooks into kernel data structures, such as the sys_call_table, and replaces or modifies system calls. After modifications, it can reload itself after a reboot. Attackers use it to control compromised machines as part of a botnet and run all types of malicious activities that include data exfiltration, unauthorized access, and hosting illegal services.
User-Mode Rootkits
It is a less complex rootkit that operates at the same privilege level as a regular software or application. It does not integrate with the core system but it is still highly effective in evading detection and performing malicious activities. Its operations are limited to resources and functions that are available to user applications. User-mode malware injects malicious dynamic-link libraries and modifies application binaries to include malicious codes. It changes API calls to hide malware activities that include logging keystrokes, taking screenshots, monitoring user activities, and exfiltrating data from the device.
Hacker Defender is a prime example of a user-mode rootkit that was developed to target Windows XP and Windows 2000 operating systems. It masks network ports, creates backdoor,s and hides its processes from the task manager. It hides files, processes, and network connections making it difficult for basic security tools to detect. As a result, it can efficiently run its malicious operations in the background.
Bootkits
It is a unique type of malware that infects the boot process of a PC and embeds itself in the bootloader or firmware. Due to this, it can run malicious code even before the operating system starts. This gives the bootkit significant control over the system and makes it very difficult to detect and remove. Even after reinstalling your operating system, it can persist in the device.
There are different types of bootkits such as MBR Bootkits, VBR Bootkits, UEFI Bootkits, and Hybrid Bootkits. Each one targets different parts and elements in the device. Notable examples of rootkits are TDL4/Alureon, Lojax, Necurs, and Rovnix. Hackers use these malicious programs to steal financial data, install additional malware, modify system settings, and scam the targeted users.
Firmware Rootkits
Firmware rootkits infect firmware in hardware such as BIOS, UEFI, network cards, or hard drives. These malware take on the first line of defense of a device. When these infected hardware parts are connected to the device malware efficiently runs its malicious operations. They can persist even after system reboots and operating system reinstallations. Cybercriminals use them to compromise sensitive information, intercept communications, and collect keystrokes.
LoJax, Mebromi, and Thunderstrike are common examples of firmware rootkits. These malware are extremely stealthy and difficult to remove. The last option you are left with is the removal or replacement of the hardware parts.
Hypervisor (Virtual Machine-Based) Rootkits
It is another highly sophisticated malware that is capable of intercepting and manipulating the operating system of a device. It operates at a higher privilege level in a device. Hypervisor embeds itself in the OS kernel and exploits the virtualization layer beneath the operating system. It creates and manages virtual machines and runs multiple operating systems on a single physical device. To create virtual machines it simulates hardware components like CPUs, memory, and storage. Due to this, the device interacts with the hypervisor as if they are communicating with physical hardware. Hackers use it for data theft, get higher-level privileges into target devices, and launch their high-level malicious operations.
Library Rootkits
Library rootkits infect system libraries to modify and hijack standard library functions. Shared libraries, like DLLs, contain reusable codes upon which multiple programs depend. Library Rootkit injects malicious codes during library calls and changes the application’s behaviour. It modifies app behaviour to run malicious operations. After this, it runs malicious operations such as hiding files, and processes, logging keystrokes, and manipulating program outputs.
LD_PRELOAD-based rootkits on Linux are the prime example of this type of malware. It exploits the dynamic linking mechanism in Unix-like operating systems. It overwrites standard library functions with malicious versions. For example, it excludes files or directories the attacker wants to hide. When data returns by functions after modifications it misleads monitoring tools or users. Attackers use this malware to steal sensitive data, such as passwords, keystrokes, and other sensitive information.
Network Rootkits
Network rootkits intercept, manipulate, or hide network activities to hide the malicious network operations invisible to the users and security tools. It operates at the network stack level and targets elements like drivers, protocols, API,s etc. to sneak and persist in the system. Hackers use it to launch man-in-the-middle (MITM) attacks, conceal malicious network communications, and steal sensitive data sent over networks.
Knark, Beastkit, and Netfilter-based Rootkits are common examples of this malware. Hackers use this malware to exfiltrate data, conceal botnet communications, and modify network-related APIs to intercept and conceal traffic. Also, it can cause latency, or traffic stuffing due to unauthorized packet processing or redirections. Linux’s Netfilter framework to intercept and manipulate packets.
Application Rootkits
This malware operates within the application layer and focuses on specific apps like web browsers, email clients, or database software. It modifies behaviour of target applications and injects malicious functionalities while appearing to have a normal appearance. To avoid detection it mimics legitimate application behavior. Application Rootkits are capable of reinstalling themselves using accompanying processes or scheduled tasks even when they are removed from the system.
Fake browser extensions, modified servers, and file utilities are some common types of application rootkits. Hackers use them to steal sensitive data such as login credentials, credit card numbers, or confidential messages. They can log user activities including keystrokes or browsing history using this malware. Additionally, it creates a backdoor for the attackers, changing app outputs and executing commands to bypass security restrictions.
Here is a colorful chart visualizing the comparison of different rootkit types based on their stealth level and difficulty of removal. Each bar represents a rootkit type, with data labels indicating their stealth level. Let me know if you’d like further customizations or additional visualizations!
Comparison of Rootkit Types
Type | Infection Target | Stealth Level | Ease of Removal |
Kernel-Level | OS Kernel | Very High | Difficult |
User-Mode | User Applications | Moderate | Easier |
Bootkits | Bootloader/MBR/UEFI | Very High | Very Difficult |
Firmware | Hardware Firmware | Extremely High | Hardware Replacement |
Hypervisor | Virtualization Layer | Very High | Very Difficult |
Library | System Libraries | Moderate | Moderate |
Network | Network Stacks/Drivers | Moderate to High | Moderate |
Application | Application Files | Low to Moderate | Easier |
What are the Signs of Rootkit Infection in a Device?
Rootkits are complex programs that operate covertly inside your device. They simulate legitimate programs, codes and executables in the system that help them hide their presence inside a system or network. They can remain active in the boot modes which makes it highly difficult to detect them. But there are some potential signs that help you confirm their presence on your PC. tracing them you can detect rootkits in your system. So, here are some signs that helps you detect the rootkits presence in your PC:
Unusual system behavior
- The operating system is extremely slow or unresponsive.
- Applications are not working and the operating system is crashing frequently.
- The device is restarting unexpectedly without you doing anything.
- No response to mouse, or keyboard inputs and blue screens.
- System setting changes and unknown programs appearing on the screen.
Irregularity in Files and Directories
- Files are lost and the directory that was visible are no longer accessible.
- The file sizes and hashes are changing unexpectedly.
- The files have unusual timestamps of creations and modifications.
Irregular Network Activity
- You will notice high network activity when no application is actively using the network.
- There will be suspicious connections and unauthorized access to remote servers.
- Rootkits change DNS servers or proxy settings without your permission.
Malfunctioning Security Tools
- Security tools and defense systems fail to operate without user action.
- It changes the rules and configurations without your permissions.
- Your device fails to download software updates or show new updates.
Suspicious Processes
- You will notice unknown and random processes running in the background.
- Resource intensive processes with unusual CPU, memory and disk usage.
Log File Irregularities
- System or application logs are missing or incomplete.
- Log files contain unknown entries and tampered with the irregularities.
Unusual Boot Behavior
- Devices infected with rootkits take significantly longer to run the boot process.
- Bootloader or MBR (Master Boot Record) is modified.
- You will notice intermittent failures during startup and boot process.
How to Prevent Rootkits?
Rootkits are highly complex malware programs that access and operate in your device at different levels. It can hijack operating system, interfere with the processes at OS, application and Kernel-Level. Since it is highly adaptable and easily hides its location it can remain hidden in the device without leaving any trace of infections. Detecting rootkits becomes quite challenging. However, if you follow best safety practices and use some pro tips you can easily deal with this deadly malware. So, here are some effective tips you can use to prevent rootkit infections:
1. Strengthen the First Line of Defense
a. Phishing Awareness
It is highly important to handle phishing attacks which includes checking sender email addresses and avoiding direct links from email messages. Open and comply to the original and legitimate emails.
b. Software Updates
Make sure to update your OS, firmware, and applications regularly to repair security flaws and close the vulnerabilities that develop over the time. It will enhance device security and seal up the backdoors hackers use to slip in malware on your PC.
2. Implement Security Tools
a. Use Antivirus Solutions
Use a robust antivirus software on your device to deal with the malware attacks, infections and remove hidden threats from the system. Scan your PC regularly to keep malware away from your device. Activate real-time protection and behavior analysis tools to catch sneaky rootkits hiding in the system mimicking the legitimate processes.
b. Secure Boot:
Use UEFI Secure Boot to block unauthorized bootloader modifications and disable rootkits at startup.
3. Monitor and Detect Threats
a. Network Monitoring
Use traffic filtering tools to detect unusual and harmful data packets and block them entering your device network. You can use firewall software to continuously monitor the network traffic. It will block the malicious data packets outside of your device and prevent the malware from infiltrating your system.
b. Analyze Logs
Regularly analyze application and system logs to detect suspicious activity or signs of any moderations and modifications.
c. Inspect Processes and Services:
Use process explorer in Windows to or top/htop Linux to recognize unusual and suspicious operations running in the operating systems.
4. Advanced Detection Techniques
a. Verify File Integrity
Use checksum tools to identify and compare system files with the original versions.
b. Scan with Specialized Tools
Use advanced tools like chkrootkit, rkhunter, or advanced antivirus software to deep scan your system and detect the hidden threats.
c. Boot from a Trusted Environment:
Use live CD/USB or a separate trusted device to boot the system to ensure no tampering is done with the OS.
