Fileless attacks definition

A fileless attack is a cyberattack that uses malicious code executed directly in memory or leveraging legitimate system tools, rather than traditional malware that relies on files stored on a disk. This stealthy approach enables fileless attacks to evade detection by most antivirus software and security solutions because they do not create easily identifiable footprints on the targeted system.

See also: zero day, advanced persistent threat

Fileless attacks examples

• PowerShell exploitation: Attackers can use the built-in Windows PowerShell scripting environment to execute malicious commands or scripts directly in memory, without leaving traces on the hard drive.
• Registry manipulation: Cybercriminals can hide malicious payloads within the Windows Registry, enabling the attack to persist and execute without creating files on the system.
• Living off the land: Fileless attacks can leverage legitimate system tools or processes, such as Windows Management Instrumentation (WMI), to carry out malicious actions while remaining undetected.

Defending against fileless attacks

• Keep software and operating systems updated to ensure the latest security patches are applied.
• Disable or restrict the use of scripting environments like PowerShell and WMI if not required for system operation.
• Implement strict user access controls to minimize the attack surface and reduce the likelihood of unauthorized access.

Further reading