// Simplified kernel APC injection (no error handling) NTSTATUS KernelInjectDll(PEPROCESS TargetProcess, char* DllPath) PVOID RemoteMemory = NULL; SIZE_T PathLen = strlen(DllPath) + 1; PKAPC pApc = NULL; PETHREAD TargetThread = NULL; // 1. Allocate memory in target process ZwAllocateVirtualMemory( TargetProcess, &RemoteMemory, 0, &PathLen, MEM_COMMIT, PAGE_READWRITE );
// Write the DLL path to the allocated memory WriteProcessMemory(hProcess, pDllPath, dllPath, strlen(dllPath), NULL);
// Allocate memory for the DLL path LPVOID pDllPath = VirtualAllocEx(hProcess, NULL, strlen(dllPath), MEM_COMMIT, PAGE_READWRITE); if (pDllPath == NULL) std::cerr << "Failed to allocate memory for DLL path." << std::endl; return 1;
The driver suspends an existing thread in the target process, modifies its context to point to the injected code, and then resumes the thread. kernel dll injector
The injector starts by loading a signed or vulnerable kernel driver ( .sys ) into the system. This driver is essential because it possesses the necessary permissions to manipulate memory outside of its own process space. 2. Locating the Target Process
Executing the Injection: There are various techniques to trigger the loading of the DLL. One common method is to create a new thread in the target process using an asynchronous procedure call (APC) or by hijacking an existing thread's execution flow. The goal is to force the process to call LoadLibrary, which loads the DLL into its memory space. Techniques and Variations
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Instead of using user-mode VirtualAllocEx , the driver directly allocates memory in the target process using ZwAllocateVirtualMemory . The DLL code is then written directly into this memory space. 5. Executing the DLL
The driver copies the payload into the newly allocated space. This can be done via ZwWriteVirtualMemory or by creating a Memory Descriptor List (MDL) using IoAllocateMdl and mapping it directly to a safe virtual address via MmMapLockedPagesSpecifyCache . Step 4: Executing the Payload
The injector must first load a signed (or unsigned with test-signing enabled) driver into the kernel. // Simplified kernel APC injection (no error handling)
Understanding the inner workings of a kernel DLL injector requires a deep dive into the architecture of Windows and the elevated privileges of the operating system's ring-0 layer. Unlike standard user-mode injectors that operate within the constraints of the Windows API, a kernel-mode injector functions at the highest level of system authority, allowing it to bypass many security measures and manipulate system memory directly. The Role of the Kernel in DLL Injection
A minor bug in the driver code or improper manipulation of kernel-mode structures will result in a Blue Screen of Death (BSOD), crashing the entire operating system.