What is Fileless Malware? The Rise of Invisible Infostealers

Traditional cybersecurity relies heavily on scanning files stored on the hard drive. However, Fileless Malware is a modern threat that completely bypasses these file-based detection mechanisms. By living entirely in the system's memory (RAM), it allows an Infostealer to harvest sensitive data without ever leaving a trace on the physical disk, making it a "ghost" in the machine.

How Do Fileless Infostealer Attacks Work?

These attacks employ a technique known as "Living-off-the-Land" (LotL), where they exploit authorized system administration tools such as PowerShell, WMI, or Task Scheduler. The lifecycle of the attack is as follows:

1. Code Injection: Malicious scripts are injected directly into the memory space of a legitimate process (e.g., Chrome.exe or Svchost.exe).
2. Credential Harvesting: Once active in the RAM, the malware scrapes the memory for stored passwords, session tokens, and credit card numbers.
3. Persistence: Attackers use registry keys or scheduled tasks to re-launch the script after a reboot, still without creating a malicious file on the disk.

The Challenge of Detecting Memory-Only Threats

Signature-based antivirus software cannot catch what it cannot see. Since there is no "malicious file" to analyze, these attacks often succeed where others fail. Dark Radar platforms counter this by monitoring anomalous behavioral patterns in memory and the misuse of administrative tools, bringing visibility to these invisible threats.

Enterprise Risks: Protecting the Memory Space

In an enterprise environment, a single fileless infection can compromise high-level administrative credentials stored in the RAM. Modern vulnerability assessments must go beyond disk scans, incorporating EDR (Endpoint Detection and Response) to identify real-time code execution anomalies within the memory.

In summary; Fileless malware represents a shift toward more sophisticated, stealth-oriented cybercrime. Defending against it requires moving away from file-based protection and toward behavioral monitoring of system memory and processes.