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NimRunPE.nim
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NimRunPE.nim
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import winim
import ptr_math
var success: BOOL
when defined(args):
const toLoadfromMem = slurp"C:\\windows\\system32\\cmd.exe"
else:
const toLoadfromMem = slurp"C:\\windows\\system32\\calc.exe"
# pass this arguments to the PE
# to use the args of the parent process just pass an empty string
when defined(args):
const exeArgs = "/c whoami"
else:
const exeArgs = ""
func toByteSeq*(str: string): seq[byte] {.inline.} =
## Converts a string to the corresponding byte sequence.
@(str.toOpenArrayByte(0, str.high))
when defined(args):
proc patchMemory*(targetAddr: pointer, data: openArray[byte]): void =
var oldProtect: DWORD
VirtualProtect(targetAddr, cast[SIZE_T](len(data)), PAGE_READWRITE, cast[PDWORD](addr(oldProtect)))
copyMem(targetAddr, unsafeAddr data[0], len(data))
VirtualProtect(targetAddr, cast[SIZE_T](len(data)), oldProtect, cast[PDWORD](addr(oldProtect)))
when defined(args):
proc patchArgFunctionMemory*(funcAddr: pointer, pNewCommandLine: pointer): void =
when defined x86:
var shellcode: seq[byte] = @[byte(0xb8)] # movabs rax, new_cmd
else:
var shellcode: seq[byte] = @[byte(0x48), byte(0xb8)] # movabs rax, new_cmd
# add new_cmd addr to shellcode
for t in cast[array[sizeOf(pointer), byte]](pNewCommandLine):
shellcode.add t
shellcode.add(byte(0xc3)) # ret
patchMemory(funcAddr, shellcode)
var memloadBytes = toByteSeq(toLoadfromMem)
var shellcodePtr: ptr = memloadBytes[0].addr
proc getNtHdrs*(pe_buffer: ptr BYTE): ptr BYTE =
if pe_buffer == nil:
return nil
var idh: ptr IMAGE_DOS_HEADER = cast[ptr IMAGE_DOS_HEADER](pe_buffer)
if idh.e_magic != IMAGE_DOS_SIGNATURE:
return nil
let kMaxOffset: LONG = 1024
var pe_offset: LONG = idh.e_lfanew
if pe_offset > kMaxOffset:
return nil
var inh: ptr IMAGE_NT_HEADERS32 = cast[ptr IMAGE_NT_HEADERS32]((
cast[ptr BYTE](pe_buffer) + pe_offset))
if inh.Signature != IMAGE_NT_SIGNATURE:
return nil
return cast[ptr BYTE](inh)
proc getPeDir*(pe_buffer: PVOID; dir_id: csize_t): ptr IMAGE_DATA_DIRECTORY =
if dir_id >= IMAGE_NUMBEROF_DIRECTORY_ENTRIES:
return nil
var nt_headers: ptr BYTE = getNtHdrs(cast[ptr BYTE](pe_buffer))
if nt_headers == nil:
return nil
var peDir: ptr IMAGE_DATA_DIRECTORY = nil
var nt_header: ptr IMAGE_NT_HEADERS = cast[ptr IMAGE_NT_HEADERS](nt_headers)
peDir = addr((nt_header.OptionalHeader.DataDirectory[dir_id]))
if peDir.VirtualAddress == 0:
return nil
return peDir
type
BASE_RELOCATION_ENTRY* {.bycopy.} = object
Offset* {.bitsize: 12.}: WORD
Type* {.bitsize: 4.}: WORD
const
RELOC_32BIT_FIELD* = 3
proc applyReloc*(newBase: ULONGLONG; oldBase: ULONGLONG; modulePtr: PVOID;
moduleSize: SIZE_T): bool =
echo " [!] Applying Reloc "
var relocDir: ptr IMAGE_DATA_DIRECTORY = getPeDir(modulePtr,
IMAGE_DIRECTORY_ENTRY_BASERELOC)
if relocDir == nil:
return false
var maxSize: csize_t = csize_t(relocDir.Size)
var relocAddr: csize_t = csize_t(relocDir.VirtualAddress)
var reloc: ptr IMAGE_BASE_RELOCATION = nil
var parsedSize: csize_t = 0
while parsedSize < maxSize:
reloc = cast[ptr IMAGE_BASE_RELOCATION]((
size_t(relocAddr) + size_t(parsedSize) + cast[size_t](modulePtr)))
if reloc.VirtualAddress == 0 or reloc.SizeOfBlock == 0:
break
var entriesNum: csize_t = csize_t((reloc.SizeOfBlock - sizeof((IMAGE_BASE_RELOCATION)))) div
csize_t(sizeof((BASE_RELOCATION_ENTRY)))
var page: csize_t = csize_t(reloc.VirtualAddress)
var entry: ptr BASE_RELOCATION_ENTRY = cast[ptr BASE_RELOCATION_ENTRY]((
cast[size_t](reloc) + sizeof((IMAGE_BASE_RELOCATION))))
var i: csize_t = 0
while i < entriesNum:
var offset: csize_t = entry.Offset
var entryType: csize_t = entry.Type
var reloc_field: csize_t = page + offset
if entry == nil or entryType == 0:
break
if entryType != RELOC_32BIT_FIELD:
echo " [!] Not supported relocations format at ", cast[cint](i), " ", cast[cint](entryType)
return false
if size_t(reloc_field) >= moduleSize:
echo " [-] Out of Bound Field: ", reloc_field
return false
var relocateAddr: ptr csize_t = cast[ptr csize_t]((
cast[size_t](modulePtr) + size_t(reloc_field)))
echo " [V] Apply Reloc Field at ", repr(relocateAddr)
(relocateAddr[]) = ((relocateAddr[]) - csize_t(oldBase) + csize_t(newBase))
entry = cast[ptr BASE_RELOCATION_ENTRY]((
cast[size_t](entry) + sizeof((BASE_RELOCATION_ENTRY))))
inc(i)
inc(parsedSize, reloc.SizeOfBlock)
return parsedSize != 0
proc OriginalFirstThunk*(self: ptr IMAGE_IMPORT_DESCRIPTOR): DWORD {.inline.} = self.union1.OriginalFirstThunk
proc fixIAT*(modulePtr: PVOID, exeArgs: Stringable): bool =
echo "[+] Fix Import Address Table\n"
var importsDir: ptr IMAGE_DATA_DIRECTORY = getPeDir(modulePtr,
IMAGE_DIRECTORY_ENTRY_IMPORT)
if importsDir == nil:
return false
var maxSize: csize_t = cast[csize_t](importsDir.Size)
var impAddr: csize_t = cast[csize_t](importsDir.VirtualAddress)
var lib_desc: ptr IMAGE_IMPORT_DESCRIPTOR
var parsedSize: csize_t = 0
while parsedSize < maxSize:
lib_desc = cast[ptr IMAGE_IMPORT_DESCRIPTOR]((
impAddr + parsedSize + cast[uint64](modulePtr)))
if (lib_desc.OriginalFirstThunk == 0) and (lib_desc.FirstThunk == 0):
break
var libname: LPSTR = cast[LPSTR](cast[ULONGLONG](modulePtr) + lib_desc.Name)
echo " [+] Import DLL: ", $libname
var call_via: csize_t = cast[csize_t](lib_desc.FirstThunk)
var thunk_addr: csize_t = cast[csize_t](lib_desc.OriginalFirstThunk)
if thunk_addr == 0:
thunk_addr = csize_t(lib_desc.FirstThunk)
var offsetField: csize_t = 0
var offsetThunk: csize_t = 0
var hmodule: HMODULE = LoadLibraryA(libname)
when defined(args):
var commandStr: string
var exeArgsPassed = false
if len(exeArgs) > 0:
commandStr = " " & exeArgs # in case commands are passed we have to prepend at least a space so that argv[1] is the first part of exeArgs
exeArgsPassed = true
if exeArgsPassed:
# patch _wcmdln and _acmdln if they are present in the import to make exeArgs working for some C++ binaries
var wcmdlenaddr = GetProcAddress(hmodule,"_wcmdln")
if wcmdlenaddr != NULL:
echo " Found _wcmdln -> patching with exeArgs"
var newCmd = newWideCString(commandStr) # we have to prepend
patchMemory(wcmdlenaddr, cast[array[sizeOf(pointer), byte]](newCmd))
var acmdlenaddr = GetProcAddress(hmodule,"_acmdln")
if acmdlenaddr != NULL:
echo " Found _wcmdln -> patching with exeArgs"
var newCmd = &(commandStr)
patchMemory(acmdlenaddr, cast[array[sizeOf(pointer), byte]](newCmd))
while true:
var fieldThunk: PIMAGE_THUNK_DATA = cast[PIMAGE_THUNK_DATA]((
cast[csize_t](modulePtr) + offsetField + call_via))
var orginThunk: PIMAGE_THUNK_DATA = cast[PIMAGE_THUNK_DATA]((
cast[csize_t](modulePtr) + offsetThunk + thunk_addr))
var boolvar: bool
if ((orginThunk.u1.Ordinal and IMAGE_ORDINAL_FLAG32) != 0):
boolvar = true
elif((orginThunk.u1.Ordinal and IMAGE_ORDINAL_FLAG64) != 0):
boolvar = true
if (boolvar):
var libaddr: size_t = cast[size_t](GetProcAddress(LoadLibraryA(libname),cast[LPSTR]((orginThunk.u1.Ordinal and 0xFFFF))))
fieldThunk.u1.Function = ULONGLONG(libaddr)
echo " [V] API ord: ", (orginThunk.u1.Ordinal and 0xFFFF)
if fieldThunk.u1.Function == 0:
break
if fieldThunk.u1.Function == orginThunk.u1.Function:
var nameData: PIMAGE_IMPORT_BY_NAME = cast[PIMAGE_IMPORT_BY_NAME](orginThunk.u1.AddressOfData)
var byname: PIMAGE_IMPORT_BY_NAME = cast[PIMAGE_IMPORT_BY_NAME](cast[ULONGLONG](modulePtr) + cast[DWORD](nameData))
var func_name: LPCSTR = cast[LPCSTR](addr byname.Name)
var libaddr: csize_t = cast[csize_t](GetProcAddress(hmodule,func_name))
echo " [V] API: ", func_name
fieldThunk.u1.Function = ULONGLONG(libaddr)
when defined(args):
# patch common Win32 functions to get the command line
if exeArgsPassed and "GetCommandLineW" == $$func_name:
echo " [>] Patching function to pass exeArgs: ", func_name
patchArgFunctionMemory(cast[pointer](libaddr), cast[pointer](newWideCString(commandStr)))
if exeArgsPassed and $$"GetCommandLineA" == func_name:
echo " [>] Patching function to pass exeArgs: ", func_name
patchArgFunctionMemory(cast[pointer](libaddr), cast[pointer](&commandStr))
inc(offsetField, sizeof((IMAGE_THUNK_DATA)))
inc(offsetThunk, sizeof((IMAGE_THUNK_DATA)))
inc(parsedSize, sizeof((IMAGE_IMPORT_DESCRIPTOR)))
return true
proc ExecTLSCallbacks*(baseAddress: PVOID) =
var tlsDir: ptr IMAGE_DATA_DIRECTORY = getPeDir(baseAddress,
IMAGE_DIRECTORY_ENTRY_TLS)
var ntHeader: ptr IMAGE_NT_HEADERS = cast[ptr IMAGE_NT_HEADERS](getNtHdrs(cast[ptr byte](baseAddress)))
if tlsDir == nil:
echo "[-] No TLS Directory found"
return
else:
echo "[+] TLS Directory found"
var tls: ptr IMAGE_TLS_DIRECTORY = cast[ptr IMAGE_TLS_DIRECTORY](
cast[ULONGLONG](baseAddress) + tlsDir.VirtualAddress)
var tlsCallback: ptr ULONGLONG = cast[ptr ULONGLONG](tls.AddressOfCallBacks)
while tlsCallback[] != 0:
echo " [+] TLS Callback: ", repr(&tlsCallback[])
var callback: proc(hinstDLL: HINSTANCE, fdwReason: DWORD, lpvReserved: LPVOID): void {.cdecl.} = cast[proc(hinstDLL: HINSTANCE, fdwReason: DWORD, lpvReserved: LPVOID): void {.cdecl.}](tlsCallback[])
try:
callback(cast[HINSTANCE](baseAddress), DLL_PROCESS_ATTACH, nil)
except:
echo "[-] TLS Callback failed"
tlsCallback = tlsCallback + 1
var pImageBase: ptr BYTE = nil
var preferAddr: LPVOID = nil
var ntHeader: ptr IMAGE_NT_HEADERS = cast[ptr IMAGE_NT_HEADERS](getNtHdrs(shellcodePtr))
if (ntHeader == nil):
echo "[+] File isn\'t a PE file."
quit()
var relocDir: ptr IMAGE_DATA_DIRECTORY = getPeDir(shellcodePtr,IMAGE_DIRECTORY_ENTRY_BASERELOC)
preferAddr = cast[LPVOID](ntHeader.OptionalHeader.ImageBase)
echo "[+] Exe File Prefer Image Base at \n"
echo "Size:"
echo $ntHeader.OptionalHeader.SizeOfImage
pImageBase = cast[ptr BYTE](VirtualAlloc(preferAddr,
ntHeader.OptionalHeader.SizeOfImage,
MEM_COMMIT or MEM_RESERVE,
PAGE_EXECUTE_READWRITE))
if (pImageBase == nil and relocDir == nil):
echo "[-] Allocate Image Base At Failure.\n"
quit()
if (pImageBase == nil and relocDir != nil):
echo"[+] Try to Allocate Memory for New Image Base\n"
pImageBase = cast[ptr BYTE](VirtualAlloc(nil,
ntHeader.OptionalHeader.SizeOfImage, MEM_COMMIT or MEM_RESERVE,
PAGE_EXECUTE_READWRITE))
if (pImageBase == nil):
echo"[-] Allocate Memory For Image Base Failure.\n"
quit()
echo"[+] Mapping Section ..."
ntHeader.OptionalHeader.ImageBase = cast[ULONGLONG](pImageBase)
copymem(pImageBase, shellcodePtr, ntHeader.OptionalHeader.SizeOfHeaders)
var SectionHeaderArr: ptr IMAGE_SECTION_HEADER = cast[ptr IMAGE_SECTION_HEADER]((cast[size_t](ntHeader) + sizeof((IMAGE_NT_HEADERS))))
var i: int = 0
while i < cast[int](ntHeader.FileHeader.NumberOfSections):
echo " [+] Mapping Section :", $(addr SectionHeaderArr[i].addr.Name)
var dest: LPVOID = (pImageBase + SectionHeaderArr[i].VirtualAddress)
var source: LPVOID = (shellcodePtr + SectionHeaderArr[i].PointerToRawData)
copymem(dest,source,cast[DWORD](SectionHeaderArr[i].SizeOfRawData))
inc(i)
var goodrun = fixIAT(pImageBase, exeArgs)
ExecTLSCallbacks(pImageBase)
if pImageBase != preferAddr:
if applyReloc(cast[ULONGLONG](pImageBase), cast[ULONGLONG](preferAddr), pImageBase,
ntHeader.OptionalHeader.SizeOfImage):
echo "[+] Relocation Fixed."
var retAddr: HANDLE = cast[HANDLE](pImageBase) + cast[HANDLE](ntHeader.OptionalHeader.AddressOfEntryPoint)
echo "Run Exe Module:\n"
var thread = CreateThread(nil, cast[SIZE_T](0), cast[LPTHREAD_START_ROUTINE](retAddr), nil, 0, nil)
WaitForSingleObject(thread, cast[DWORD](0xFFFFFFFFF))