OSEP DeHospital Walkthrough Part 1: Bypassing EDR for Initial Access

The DeHospital environment is one of the most notoriously difficult, heavily fortified networks in the Offensive Security Experienced Penetration Tester (OSEP) curriculum. Conquering the DeHospital infrastructure begins with surviving the perimeter. If you cannot bypass the simulated Endpoint Detection and Response (EDR) systems, your PEN-300 exam is over before it begins.

Crafting the Undetectable Payload

The perimeter of the DeHospital network is unforgiving. Standard web shells and public GitHub exploits will trigger the AV immediately, cutting off your initial access. You must craft highly obfuscated C# payloads tailored for this specific environment.

• Dynamic API Resolution: Do not use standard P/Invoke signatures in your C# dropper. You must dynamically resolve Windows APIs using delegates to hide your malicious imports from static analysis.
• Process Injection: Bypassing the DeHospital AV requires injecting your encrypted shellcode into legitimate, trusted binaries (like svchost.exe or explorer.exe) to establish a stable, undetected C2 session.