Infographic illustrating in-memory PE loader attack: steps from downloading via InternetOpenUrlA to mapping sections, resolving imports, and executing payload; icons for EDR evasion, trusted process hijack, and recommendations for advanced memory inspecti

Hackers are increasingly using an in-memory Portable Executable (PE) loader to bypass Endpoint Detection and Response (EDR) tools, executing malicious code within trusted processes without writing to disk. This fileless technique, highlighted by researcher G3tSyst3m, starts with a legitimate process downloading a PE file (e.g., RAT or info-stealer) from sources like GitHub via Windows APIs (InternetOpenUrlA, InternetReadFile), storing it in a memory buffer—often dismissed as benign network traffic.

Infographic illustrating in-memory PE loader attack: steps from downloading via InternetOpenUrlA to mapping sections, resolving imports, and executing payload; icons for EDR evasion, trusted process hijack, and recommendations for advanced memory inspectiInfographic illustrating in-memory PE loader attack: steps from downloading via InternetOpenUrlA to mapping sections, resolving imports, and executing payload; icons for EDR evasion, trusted process hijack, and recommendations for advanced memory inspecti

The loader then emulates Windows' native loader: parsing DOS/NT headers for structure; allocating memory with VirtualAlloc; mapping sections (.text for code, .data for variables) to virtual addresses; resolving imports via LoadLibraryA/GetProcAddress; applying relocations for address fixes; setting permissions with VirtualProtect (executable for code, read/write for data); and calling the entry point to run the payload. This stealthy process evades file-scanning AV/EDR like Microsoft Defender and Sophos XDR, succeeding in red team tests despite potential behavioral flags from AI/ML.

Infographic illustrating in-memory PE loader attack: steps from downloading via InternetOpenUrlA to mapping sections, resolving imports, and executing payload; icons for EDR evasion, trusted process hijack, and recommendations for advanced memory inspectiInfographic illustrating in-memory PE loader attack: steps from downloading via InternetOpenUrlA to mapping sections, resolving imports, and executing payload; icons for EDR evasion, trusted process hijack, and recommendations for advanced memory inspecti

The method exposes EDR blind spots, emphasizing the need for advanced memory forensics, process behavior monitoring, and beyond-file-based defenses to counter such evasion tactics.
 
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