Careto

Also known as: The Mask

Category: Malware, advanced persistent threat (APT), cyber espionage

Type: Remote access trojan (RAT), spyware, backdoor

Platform: Windows, Linux (less common) 

Damage potential: Espionage, system control, unauthorized access, data exfiltration, intellectual property theft, surveillance, long-term access.

Overview

Careto (also known as The Mask) is a highly sophisticated cyber espionage tool designed to target governments, corporations, and high-profile organizations worldwide. First identified by Kaspersky Lab in 2014, Careto is primarily a RAT that enables attackers to maintain long-term, stealthy access to infected systems. Unlike typical ransomware, Careto is not focused on mass extortion but on targeted attacks for espionage purposes.

This malware is known for its ability to infiltrate networks, exfiltrate sensitive data, and maintain persistence without detection. It has a range of custom backdoors and tools to support long-term access to compromised systems, facilitating espionage and intelligence gathering. The malware can execute a wide variety of malicious activities, including data exfiltration and keystroke logging. 

Careto operates with remarkable stealth, utilizing techniques such as steganography — hiding malicious code within innocuous-looking files, such as system files, related to systems processes or authentic files of trusted providers. That allows this RAT to bypass traditional detection mechanisms and target critical sectors, including government institutions, energy, telecommunications, and financial organizations.

Possible symptoms

Careto is quite hard to detect because its nature is to exfiltrate information while not damaging the target’s device. However, the presence of this RAT on a system might manifest through several indicators, including:

• Unfamiliar processes running in Task Manager or unexpected network activity.
• Files appearing with unfamiliar extensions.
• Presence of unusual files in directories.
• Outbound connections to unknown or suspicious IP addresses.

Sources of the infection

Careto might get into the system through the organization's web servers, which had been previously compromised by threat actors. The infection process typically triggers when a user connects to the web server, allowing the malware to be installed.

Additional infection methods include:

• Exploitation of software vulnerabilities.
• Bundling with third-party software.

Protection

To protect your network from Careto and similar threats, combine as many of the following tips as possible: 

• Monitor network traffic. Set up firewalls and network monitoring tools to detect suspicious outbound connections.
• Train users. Educate employees to recognize phishing attempts and avoid clicking on unknown email attachments.
• Never open suspicious files in emails. Be wary of malicious attachments in emails from unfamiliar senders.
• Use multi-factor authentication (MFA). Secure remote access and accounts with MFA to prevent unauthorized access. 
• Only trust official sources. Never download software from pirated websites.
• Set up strong passwords. Create complex and unique passwords that contain upper- and lowercase letters, numbers, and special characters.
• Backup data. Maintain regular, offline backups to ensure that encrypted data can be restored without paying the ransom.
• Use Threat Protection Pro™. This NordVPN's advanced antivirus tool is designed to make browsing safer by blocking malicious ads and compromised websites and scanning your downloads for malware. 
• Keep your systems updated. Regularly install updates for your Windows operating system and other software to patch known vulnerabilities.
• Use endpoint security. Ensure robust endpoint protection with modern antivirus solutions that can detect and block ransomware behaviors.

Removal

If you suspect your device has been infected with Careto, act immediately. 

• Disconnect from the internet. This will prevent further data exfiltration and malware communication.
• Boot into safe mode. Safe mode allows users to safely review and remove suspicious files.
• Terminate suspicious processes. Open Task Manager, stop suspicious tasks from running, and carefully review those that seem to be using the most processing power.
• Remove malicious files and registry entries. Delete all suspicious files and registry keys associated with the infection.
• Run a full system scan. Use a reputable antivirus or anti-malware program to run a scan, and delete everything that it returns.
• Restore from backup. If available, restore your files from a clean, uninfected backup.
• Change all passwords. Since Careto is capable of stealing credentials, change the passwords for any systems, accounts, or services accessed by the infected device.
• Monitor the system. After removal, monitor your system for signs of reinfection. Use advanced threat detection tools for continuous security.