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Infostealer Malware 101: A Comprehensive Guide

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In 2023, the global average cost of a data breach soared to $4.45 million. Among the various types of malicious software targeting individuals and organizations, Infostealer malware stands out for its stealthy nature. This article takes a closer look at Infostealer malware, exploring its mechanisms and impact in detail.

An information stealer (or infostealer) is a malicious trojan that steals sensitive information from a system or network. It collects login credentials and sends it to another system either via email or over a network. Infostealer malware poses significant threats to industries ranging from Finance, Retail, Government to Healthcare. Infostealer can lead to severe consequences, including unauthorized transactions, money theft, tarnished trust, and legal liabilities in industries with stringent data protection regulations.

History and Evolution of Infostealer Malware

  1. Early Forms of Infostealers (1990s): In the early days of the internet, infostealers primarily targeted personal computers and were often distributed via email attachments, infected software downloads, or compromised websites.
  2. Keylogging Trojans (early 2000s): Keylogging Trojans emerged as a prevalent form of infostealer malware. They could log keystrokes, capturing sensitive information, such as usernames, passwords, credit card details, banking credentials and other personal data. Some of the well-known keylogger were ZeuS/Zbot Trojan, KeyGrabber USB and Ghost Keylogger.
  3. Banking Trojans (Mid-2000s): Infostealer malware gained more prominence in 2006 with banking Trojans, which specifically targeted online banking credentials and financial information. Banking Trojans such as Spy Eye, Citadel, and Dyre emerged as prominent threats. They used advanced techniques to steal banking credentials, stop transactions, and manipulate online banking sessions.
  4. Expansion of Targets and Capabilities (Late 2000s to Early 2010s): During this period, Infostealer malware expanded to a wide range of targets and capabilities, covering industries like healthcare, retail and government and becoming prevalent in stealing personal and corporate data.
  5. Continued Innovation and Sophistication (2010–Present): Today, Infostealer malware continues to evolve with advancements in technology and cybercriminal tactics. Modern infostealer malware variants such as Raccoon, Vidar, and RedLiner Infostealer exhibit increased sophistication, using techniques such as ambiguous language, encryption, and polymorphism to evade detection by security solutions. It remains a prevalent and persistent threat, with new variants continually emerging to target individuals, businesses, and organizations worldwide. 

How Infostealer Malware Works

Infostealer malware infiltrate systems and steal sensitive information from various layers of the computing environment.

  • Data Layer: The malware is designed to scan compromised systems for specific categories of sensitive data such as browsing history, saved passwords, cookies, form autofill data, financial details and more.
  • Transport Layer: Once the intended data is found, the virus uses a variety of tactics to extract it from the infected system. This could include connecting to remote command-and-control servers controlled by the attackers, encrypting stolen data for transmission, or employing hidden channels to circumvent network security measures.
  • Application Layer: It targets system-installed applications and software, including web browsers, email, and chat apps. It uses the existing vulnerabilities in these programs to obtain access to sensitive data, such as login credentials and browsing.

Examples of Infostealer Malware

There have been three major Infostealer malware families that have become increasingly common. They are RedLine, Raccoon and Vidar.

  RedLine infostealer  Raccoon Infostealer  Vidar Infostealer 
Introduction  Emerged in 2020, RedLine runs on a malware-as-a-service (MaaS) platform tricking users into clicking on malicious files or attachments to gain access.  Identified in 2019, Raccoon infects systems via keylogging, login theft, data harvesting, browser hijacking, cryptocurrency theft and remote access.  Discovered in the late 2018, Vidar Infostealer spreads by downloading an unauthorized application from an untrustworthy source.  
Severity  High  High  High 
Functionality  It can retrieve a variety of sensitive data from compromised systems. It secretly captures this information and transfers it to distant servers controlled by attackers 

It acts secretly, evading security solutions and secretly exfiltrating stolen data to remote attacker-controlled servers.    

It is meant for stealing sensitive information from infected systems 


It captures information through a variety of methods, like keylogging, screen capture, and data theft, before transferring it to remote attacker-controlled sites 
Distribution  Phishing emails, illegal websites, and exploit kits to trick people into downloading and installing the malware on their devices  Social engineering tactics like phishing emails, illicit websites, exploit kits as well as known vulnerabilities  Phishing emails, illicit websites, and exploit kits, zero days and known vulnerabilities 
Impact  Monetary damage, breach of privacy, reputational harm, and compliance violations  Financial losses, privacy violations, reputational damage and regulatory compliance issues  Financial losses, privacy violations, reputational damage, non-compliance, unauthorized access   
Prevention  Cyber Awareness Training, Security Updates, Proactive Threat Hunt, Monitor Dark Web Avanced endpoint protection, strong access controls and multi-factor authentication Endpoint Security, Employee Training, MFA, Email and Web Security

How to Stay Protected from Infostealer Malware

The prevention techniques vary according to the threats. To protect against Infostealer, businesses must create a comprehensive cyber security strategy. Some common preventive measures include a multi-layered security approach, regular software updates, multi-factor authentication, continuous monitoring of systems and network with an incident response plan.

Conclusion: Protecting against InfoStealer malware requires a proactive approach that addresses vulnerabilities at different layers of digital infrastructure. When businesses and individuals understand the nature of these threats and implement robust security measures, they can mitigate the risk posed by hackers. This can help safeguard the privacy and integrity of sensitive information.