Process injection is a very popular method to hide malicious behavior of code and are heavily used by malware authors.
There are several techniques, which are commonly used: DLL injection, process replacement (a.k.a process hollowing), hook injection and APC injection.
Most of them use same Windows API functions: OpenProcess, VirtualAllocEx, WriteProcessMemory, for detailed information about those functions, use MSDN.
DLL injection:
- Open target process.
- Allocate space.
- Write code into the remote process.
- Execute the remote code.
Process replacement:
- Create target process and suspend it.
- Unmap from memory.
- Allocate space.
- Write headers and sections into the remote process.
- Resume remote thread.
Hook injection:
- Find/Create process.
- Set hook
APC injection:
- Open process.
- Allocate space.
- Write code into remote threads.
- "Execute" threads using QueueUserAPC.
Download
Windows x64 binary - x64 bit DEMO
Dependencies:
vc_redist.x64 - Microsoft Visual C++ Redistributable
DEMO