How Can Processes Be Created Directly From Memory Buffers Without File Storage?

Creating Processes from Memory Buffers

In this post, we'll explore a technique to spawn processes directly from memory buffers without the need for file storage. This can be useful scenarios involving code injection or secure patching, such as in the provided backstory.

The Technical Breakdown

Windows provides the CreateProcess API with the CREATE_SUSPENDED flag, allowing processes to be kept suspended until the ResumeThread function is invoked. This window provides an opportunity to manipulate process memory and context before execution.

1. Suspend and Inspect the Process: Suspend the process using CreateProcess(CREATE_SUSPENDED) and retrieve the suspended thread's context using GetThreadContext.
2. Identify Base Address: The EBX register will contain a pointer to the Process Enviroment Block (PBE) structure. The ImageBaseAddress can be found at offset 8 within the PBE.
3. Prepare the In-Memory EXE: If the base addresses of the suspended process and in-memory EXE match and the in-memory EXE is smaller or equal in size, write it directly to the suspended process' memory using WriteProcessMemory.
4. Magic Required: If the conditions in step 3 are not met, unmap the original image (ZwUnmapViewOfSection), allocate memory using VirtualAllocEx, and write the in-memory EXE using WriteProcessMemory.
5. Patch PEB and Thread Context: Update the suspended process' ImageBaseAddress with the in-memory EXE's base address, patch the thread context's EntryPoint address, and save the altered context using SetThreadContext.
6. Resume Execution: Resume the suspended process using ResumeThread to execute the in-memory EXE.

Conclusion

By following these steps, it is possible to create processes from memory buffers, offering flexibility in code injection and secure patching scenarios.

The above is the detailed content of How Can Processes Be Created Directly From Memory Buffers Without File Storage?. For more information, please follow other related articles on the PHP Chinese website!