Cybersecurity

Infostealer: A Silent Threat in Cybersecurity

Infostealers, also known as data-stealing malware, have emerged as a significant threat in the cybersecurity landscape. Unlike ransomware, they do not encrypt files or demand payment, but they facilitate some of the most destructive cyberattacks on businesses. These malware programs are designed to harvest and sell millions of access credentials quietly.

A Discreet Yet Systemic Threat

Infostealers are deployed without user knowledge via malicious files, such as cracked software, browser extensions, or email attachments. They collect a range of data from infected systems, including saved passwords, session cookies, browsing histories, VPN credentials, email access, internal dashboards, and sometimes even files or screenshots. Once collected, this information is sent to remote servers and then integrated into databases known as logs, which are sold or exchanged on cybercriminal marketplaces.

A Structured Industry with Minimal Costs

Logs are files containing thousands of raw credentials. These files are sold for a few euros each, sometimes bundled by country, company, or industry. Platforms have industrialized this model, and initial access brokers (IABs) specialize in selling premium access, targeting vulnerable but high-value companies.

A Gateway to Final Attacks

Once credentials are acquired, they can be used in various ways:

• Directly accessing internal systems undetected due to a lack of MFA or behavioral monitoring.
• Massively scraping databases using the acquired access.
• Selling access to more organized groups, leading to ransomware attacks, extortion, or massive data exfiltration.

Accessible Tools and Unaware Victims

Infostealers are not confined to seasoned cybercriminals. They are accessible to any malicious actor with 50 euros and a basic tutorial. The ease of infection among corporate or public sector employees, often through free browser extensions or cracked office software, is concerning. A single click is enough.

In most cases, victims remain unaware of the breach. The malware does not slow the system, display alerts, or alter visible behavior. The danger often remains hidden until a major incident reveals the damage.

An Incomplete Response

Despite the magnitude of the issue, few organizations have adjusted their security policies, with budgets largely focused on perimeter protection or anti-ransomware solutions. This leaves a critical blind spot in post-infection detection and data leak analysis.

Recommended measures include:

• Prohibiting password reuse,
• Consistently implementing MFA,
• Deploying behavioral detection solutions (EDR/NDR),
• Training all employees on the risks associated with infostealers.