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Alureon

Also known as: TDL-4, TDSS

Category: Malware

Type: Rootkit-based malware

Platform: Windows

Variants: The TDL-1, TDL-2, TDL-3, and TDL-4 variants utilize advanced rootkit techniques, with some featuring bootkit capabilities to ensure persistence via Master Boot Record (MBR) modification.

Damage potential: Enables unauthorized access to infected systems, steals sensitive information, redirects traffic to malicious sites, and allows for remote commands through botnet infrastructure for potential DDoS attacks, spam distribution, and further malware propagation.

Overview

Alureon malware, also known as TDL-4 or TDSS, first appeared on the cyberthreat landscape in the late 2000s. It functions as an information stealer and remote-controlled botnet agent, using sophisticated rootkit and bootkit techniques. Threat researchers link Alureon to cybercriminal activities involving data theft, persistent surveillance, malware distribution, and large-scale credential theft campaigns targeting individuals and businesses.

Once Alureon infects a system, it modifies the master boot record (MBR) to establish deep-rooted persistence, allowing it to survive reboots and system reinstallations. It’s difficult to detect Alureon because it operates in the kernel of the infected Windows system.

Alureon can intercept and capture sensitive data, including login credentials and financial information, which it then sends to a command and control (C2) server. This malware can also download and execute other malicious payloads, launch additional attacks, spread more malware, or use infected machines in botnet activities such as distributed denial-of-service (DDoS) attacks or spam distribution.

Possible symptoms

Alureon can significantly affect system performance due to its background activities, such as intercepting network traffic, sending data to C2 servers, and loading additional malicious modules. Other possible symptoms of an Alureon infection include:

  • Slow or unresponsive system performance.
  • Frequent system crashes or the blue screen of death.
  • Spikes in network activity.
  • Unknown or suspicious processes in the Task Manager.
  • Increased CPU or memory usage.
  • Disabled security programs.
  • Redirection of web traffic.

Sources of the infection

Cybercriminals may use various methods to infect systems with Alureon:

  • Phishing emails. Attackers design fake emails that look legitimate to trick you into clicking on a link or downloading an attachment, which installs Alureon onto your system.
  • Drive-by downloads. If you visit a compromised or malicious website and interact with its content by clicking links or ads, you might unknowingly download Alureon onto your system.
  • Embedding Alureon into compromised software. Attackers may embed Alureon within software updates, free downloads from untrusted sites, or pirated software. When you install these programs, Alureon gains access to your system, often undetected.
  • Exploiting network vulnerabilities. Cybercriminals may exploit security vulnerabilities, such as outdated operating systems, software, or weak network configurations, to inject Alureon directly onto a target device.
  • Infecting USBs or removable media. Alureon may spread through infected USB drives or removable media. It automatically installs on your system once you access the drive.

Protection

The best way to protect against Alureon is to educate yourself about rootkit-based malware and hackers’ techniques to infiltrate computer systems. The most effective measures to protect against Alureon include:

  • Using antivirus and anti-malware software. Install and regularly update reliable antivirus software that includes rootkit detection to prevent Alureon and similar threats.
  • Regularly updating systems and software. Keep your operating system, browsers, and all applications up to date to patch known vulnerabilities.
  • Using Threat Protection Pro™. Purchase NordVPN with the advanced Threat Protection Pro™ feature, which blocks malicious sites and scans files for malware as you download them.
  • Filtering email. Use advanced email filtering solutions to block phishing emails and malicious attachments.
  • Avoiding suspicious links and attachments. Never click on unfamiliar links or suspicious attachments, especially from unknown senders.
  • Improving network security. Set up firewalls, intrusion detection systems, and endpoint protection to detect and block Alureon’s attempts to establish command and control connections.
  • Using a password manager. Never keep your passwords written in plain text on your computer. Use a trusted password manager like NordPass, which allows you to store all your credentials under one master password.
  • Implementing multi-factor authentication (MFA). MFA adds an extra layer of security to your accounts, making unauthorized access more difficult.
  • Monitoring network traffic. Use network monitoring tools to detect unusual activity that may indicate a malware infection.

Removal of Alureon

If you suspect Alureon has infected your system, immediately disconnect your device from the internet to cut communication with the malware’s C2 servers. Next, restart your computer in safe mode to limit the rootkit’s ability to operate undetected.

Run a full system scan with reputable antivirus or anti-rootkit software to detect and remove Alureon. Follow the steps recommended by the software to ensure thorough malware removal. Allow the antivirus program to quarantine or delete any detected threats.

Once you have removed Alureon from your system, change all your online account passwords to strong, unique ones to protect your data. If the malware persists or you cannot remove it completely, contact a cybersecurity professional for help.