Infostealers: Understanding the Threat Landscape

What Are Infostealers?

Infostealers (also known as information stealers or credential stealers) are a category of malicious software designed to extract sensitive information from infected systems. These sophisticated threats operate covertly, harvesting valuable data including login credentials, personal information, financial details, and system configurations without the user's knowledge.

Unlike ransomware or other disruptive malware, infostealers prioritize stealth operations to maximize data collection over extended periods. They typically target stored credentials in web browsers, email clients, cryptocurrency wallets, gaming platforms, and various applications that store sensitive user data.

How Infostealers Work

Distribution Methods

Infostealers commonly spread through:

• Phishing emails containing malicious attachments or links
• Software bundling with legitimate-appearing applications
• Exploit kits targeting unpatched vulnerabilities
• Social engineering campaigns on social media and forums
• Malicious advertisements (malvertising) on compromised websites
• Supply chain attacks targeting software distribution channels

Data Collection Techniques

Once installed, infostealers employ various techniques to harvest information:

• Browser data extraction: Saved passwords, cookies, browsing history, and autofill data
• Keylogging: Recording keystrokes to capture typed credentials
• Screen capture: Taking screenshots of sensitive applications
• File system scanning: Searching for specific file types containing valuable information
• Memory dumping: Extracting credentials from system memory
• Application targeting: Specifically targeting cryptocurrency wallets, VPNs, and business applications

Why Infostealers Are Particularly Dangerous

Stealth and Persistence

Infostealers are designed to remain undetected for extended periods, often employing:

• Anti-detection techniques to evade antivirus software
• Legitimate process mimicking to blend in with normal system operations
• Minimal system impact to avoid performance degradation that might alert users
• Encrypted communication with command and control servers

High-Value Target Data

The information collected by infostealers is particularly valuable because it includes:

• Multi-factor authentication bypass tokens that can circumvent security measures
• Session cookies allowing immediate access without password requirements
• Cryptocurrency wallet data providing direct access to digital assets
• Corporate credentials that can lead to business email compromise
• Personal identifying information useful for identity theft

Scale of Operation

Modern infostealers can:

• Automate data collection across thousands of infected systems simultaneously
• Target multiple applications in a single infection
• Operate across different operating systems and device types
• Maintain persistent access through various survival mechanisms

Threat Actor Activities with Compromised Credentials

Initial Access and Reconnaissance

When threat actors obtain stolen credentials, they typically:

• Validate credentials across multiple platforms to determine their scope of access
• Conduct reconnaissance to understand the victim's digital footprint
• Map organizational structures to identify high-value targets within companies
• Assess the value of different accounts for potential monetization

Account Takeover Operations

Threat actors use compromised credentials for:

• Financial fraud including unauthorized transactions and account draining
• Cryptocurrency theft through direct wallet access or exchange account compromise
• Social media hijacking for disinformation campaigns or further credential harvesting
• Email account compromise to conduct business email compromise (BEC) attacks
• Subscription and service abuse using victims' paid accounts

Lateral Movement and Escalation

In corporate environments, stolen credentials enable:

• Horizontal movement across network resources using compromised user accounts
• Privilege escalation by targeting administrative or service accounts
• Domain compromise through credential stuffing and password spraying attacks
• Service account abuse to maintain persistent access to critical systems

Path to Data Breaches

Initial Compromise

Infostealers create the foundation for data breaches by:

• Providing valid credentials that bypass perimeter security controls
• Offering multiple entry points through various compromised accounts
• Enabling reconnaissance to identify high-value targets within organizations
• Establishing persistence through legitimate credential usage

Breach Progression

The progression from infostealer infection to data breach typically follows:

• Credential Harvesting: Initial malware infection collects user credentials
• Access Validation: Threat actors test credentials across corporate systems
• Initial Access: Successful authentication using stolen credentials
• Environment Mapping: Discovery of network topology and sensitive data locations
• Privilege Escalation: Using additional credentials to gain higher-level access
• Data Identification: Locating and cataloging valuable information
• Data Exfiltration: Systematic extraction of sensitive information
• Cover-up Activities: Attempting to hide evidence of the breach

Amplification Factors

Several factors can amplify the impact of infostealer-initiated breaches:

• Credential reuse across multiple systems and platforms
• Weak password policies that make credential stuffing attacks more effective
• Insufficient monitoring that allows prolonged unauthorized access
• Over-privileged accounts that provide excessive access to sensitive resources

Associated Malicious Activities

Financial Cybercrime

• Banking fraud through direct account access or wire transfer authorization
• Credit card fraud using harvested payment information
• Cryptocurrency theft via wallet compromise or exchange account takeover
• Tax fraud using stolen personal identifying information
• Insurance fraud through identity theft and false claims

Business Email Compromise (BEC)

• CEO fraud using compromised executive email accounts
• Vendor impersonation through supply chain email compromise
• Payroll redirection by compromising HR email accounts
• Invoice fraud using compromised accounting department credentials

Identity Theft and Fraud

• Document fraud using harvested personal information
• Social Security fraud through identity appropriation
• Medical identity theft for fraudulent healthcare claims
• Government benefits fraud using stolen identities

Ransomware and Extortion

• Ransomware deployment using compromised credentials for initial access
• Double extortion combining data theft with encryption attacks
• Credential-based extortion threatening to expose compromised accounts
• Competitive intelligence theft for corporate espionage

Supply Chain Attacks

• Vendor compromise through stolen partner credentials
• Software supply chain infiltration using developer account access
• Third-party service abuse through compromised integration accounts
• Cloud service pivoting using stolen cloud platform credentials

Mitigation and Prevention Strategies

Technical Controls

• Multi-factor authentication implementation across all critical systems
• Privileged access management to limit credential exposure
• Endpoint detection and response solutions to identify infostealer infections
• Network segmentation to limit lateral movement opportunities
• Regular credential rotation and password policy enforcement

Organizational Measures

• Security awareness training focusing on phishing and social engineering
• Incident response planning specifically addressing credential compromise
• Regular security assessments including credential hygiene audits
• Vendor risk management to address supply chain credential exposure
• Continuous monitoring for compromised credentials on dark web markets

Individual Best Practices

• Unique password usage across different platforms and services
• Password manager adoption to generate and store complex passwords securely
• Regular software updates to patch vulnerabilities exploited by infostealers
• Cautious browsing habits to avoid malicious websites and downloads
• Email security awareness to recognize and avoid phishing attempts

Conclusion

Infostealers represent a critical threat in the modern cybersecurity landscape, serving as the gateway for numerous downstream attacks including data breaches, financial fraud, and ransomware deployment. Their stealth nature, combined with the high value of harvested credentials, makes them particularly dangerous for both individuals and organizations.

The most effective defense against infostealers requires a comprehensive approach combining technical controls, organizational policies, and user education. Given the evolving nature of these threats, continuous monitoring and adaptive security measures are essential for maintaining protection against this persistent and growing threat category.

Organizations must recognize that infostealer infections often precede more serious security incidents and should prioritize both prevention and rapid response capabilities to minimize the potential impact of credential compromise.

Updated on: 07/08/2025