Malicious actors have been spotted using an especially sneaky fileless malware technique -- reflective dynamic-link library (DLL) injection -- to infect victims with Netwalker ransomware in hopes of making the attacks untraceable while frustrating security analysts.

In a company blog post on Monday, Trend Micro threat analyst Karen Victor writes that instead of compiling the malware and storing it into the disk, the adversaries are writing it in PowerShell and executing it directly into memory.

"This technique is stealthier than regular DLL injection because aside from not needing the actual DLL file on disk, it also does not need any windows loader for it to be injected. This eliminates the need for registering the DLL as a loaded module of a process, and allowing evasion from DLL load monitoring tools," the Trend Micro blog post explains.

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