首先说说 KeUserModeCallback
之前做某个项目时,用到了KeUserModeCallback的方式执行用户态的shellcode.
当时遗留了一个问题,关于wow64下,KeUserModeCallback的分发没有搞清楚.
导致只能执行原生的shellcode.
普通的32位和64位模式下原生的KeUserModeCallback执行ring3代码大家都不陌生了.
详情可见俄国人的ring0MsgBox.
但是如果内核所在的进程空间是一个wow64的进程,就有点麻烦了.
在内核 nt! KeUserModeCallback
-> nt! KiCallUserMode
进入Ring3之后,首先到达的分发函数是 ntdll64!KiUserCallbackDispatcher
虽然是WOW64进程,但是当前的CPU模式是 x64!是没法直接执行我们的x86 shellcode的.
.text:0000000078E9FDD6 ; NTSTATUS __stdcall KiUserCallbackDispatcher(ULONG Index, PVOID Argument, ULONG ArgumentLength)
.text:0000000078E9FDD6 public KiUserCallbackDispatcher
.text:0000000078E9FDD6 KiUserCallbackDispatcher proc near ; DATA XREF: .rdata:off_78F58128o
.text:0000000078E9FDD6
.text:0000000078E9FDD6 arg_18 = qword ptr 20h
.text:0000000078E9FDD6 arg_20 = dword ptr 28h
.text:0000000078E9FDD6 arg_24 = dword ptr 2Ch
.text:0000000078E9FDD6
.text:0000000078E9FDD6 48 8B 4C 24 20 mov rcx, [rsp+arg_18]
.text:0000000078E9FDDB 8B 54 24 28 mov edx, [rsp+arg_20]
.text:0000000078E9FDDF 44 8B 44 24 2C mov r8d, [rsp+arg_24]
.text:0000000078E9FDE4 65 48 8B 04 25 60 00 00+ mov rax, gs:60h ; rax = PEB
.text:0000000078E9FDED 4C 8B 48 58 mov r9, [rax+58h] ; r9 = KernelCallbackTable
.text:0000000078E9FDF1 43 FF 14 C1 call qword ptr [r9+r8*8]
.text:0000000078E9FDF1 KiUserCallbackDispatcher endp ; sp-analysis failed
但是系统的自带的功能是可以正常切换到wow64模式的,比如 user32!_ClientLoadLibrary.
简单IDA之后,发现系统是存在一个模式切换的过程.
以 ClientLoadLibrary为例.
首先,到达 ntdll64!KiUserCallbackDispatcher 之后, call qword ptr [r9+r8*8] 这里的地址是
wow64win !whcbClientLoadLibrary 这里都是x64的代码.
.text:0000000078BA92C3 41 B9 28 00 00 00 mov r9d, 28h ;参数的大小
.text:0000000078BA92C9 45 8B C2 mov r8d, r10d ;参数的地址
.text:0000000078BA92CC 41 8D 51 19 lea edx, [r9+19h] ; Wow64模式的ApiIndex
.text:0000000078BA92D0 48 8D 4C 24 30 lea rcx, [rsp+9F8h+pContext] ;线程的上下文
.text:0000000078BA92D5 E8 2C 69 00 00 call Wow64KiUserCallbackDispatcher
wow64win !whcbClientLoadLibrary 内部继续分发了wow64!Wow64KiUserCallbackDispatcher
void Wow64KiUserCallbackDispatcher(
OUT PCONTEXT Context, //线程上下文,需要外部分配内存
IN LONG ApiIndex, //wow64的KernelCallbackTable的ApiIndex
IN PVOID pParam,
IN ULONG ParamSize
);
wow64!Wow64KiUserCallbackDispatcher 中会复制参数到之前的context对应的栈上,
这个context已经是将来要使用的wow64模式 的context
.text:0000000078BD8A29 65 48 8B 04 25 30 00 00+ mov rax, gs:30h
.text:0000000078BD8A32 48 05 00 20 00 00 add rax, 2000h
.text:0000000078BD8A38 48 89 44 24 30 mov [rsp+348h+var_318], rax
.text:0000000078BD8A3D 48 8B 44 24 30 mov rax, [rsp+348h+var_318]
.text:0000000078BD8A42 8B 00 mov eax, [rax]
.text:0000000078BD8A44 89 84 24 18 03 00 00 mov [rsp+348h+var_30], eax
.text:0000000078BD8A4B E8 D8 46 00 00 call RunCpuSimulation
这里的 wow64!RunCpuSimulation 只是一个stub,会跳转到 wow64cpu!CpuSimulate .text:0000000078B625B0 public CpuSimulate
.text:0000000078B625B0 CpuSimulate proc near ; DATA XREF: .text:off_78B63168o
.text:0000000078B625B0 ; .pdata:0000000078B650B4o
.text:0000000078B625B0
.text:0000000078B625B0 var_B8 = qword ptr -0B8h
.text:0000000078B625B0 var_B0 = word ptr -0B0h
.text:0000000078B625B0 var_A8 = dword ptr -0A8h
.text:0000000078B625B0 var_A0 = qword ptr -0A0h
.text:0000000078B625B0 var_98 = word ptr -98h
.text:0000000078B625B0 var_48 = byte ptr -48h
.text:0000000078B625B0 var_40 = qword ptr -40h
.text:0000000078B625B0 var_38 = qword ptr -38h
.text:0000000078B625B0 var_30 = qword ptr -30h
.text:0000000078B625B0 var_28 = qword ptr -28h
.text:0000000078B625B0 var_20 = qword ptr -20h
.text:0000000078B625B0 var_18 = qword ptr -18h
.text:0000000078B625B0 var_10 = qword ptr -10h
.text:0000000078B625B0 var_8 = qword ptr -8
.text:0000000078B625B0
.text:0000000078B625B0 48 81 EC B8 00 00 00 sub rsp, 0B8h
.text:0000000078B625B7 48 89 6C 24 78 mov [rsp+0B8h+var_40], rbp
.text:0000000078B625BC 48 89 BC 24 80 00 00 00 mov [rsp+0B8h+var_38], rdi
.text:0000000078B625C4 48 89 B4 24 88 00 00 00 mov [rsp+0B8h+var_30], rsi
.text:0000000078B625CC 48 89 9C 24 90 00 00 00 mov [rsp+0B8h+var_28], rbx
.text:0000000078B625D4 4C 89 A4 24 98 00 00 00 mov [rsp+0B8h+var_20], r12
.text:0000000078B625DC 4C 89 AC 24 A0 00 00 00 mov [rsp+0B8h+var_18], r13
.text:0000000078B625E4 4C 89 B4 24 A8 00 00 00 mov [rsp+0B8h+var_10], r14
.text:0000000078B625EC 4C 89 BC 24 B0 00 00 00 mov [rsp+0B8h+var_8], r15
.text:0000000078B625F4 4C 8D 74 24 70 lea r14, [rsp+0B8h+var_48]
.text:0000000078B625F9 65 4C 8B 24 25 30 00 00+ mov r12, gs:30h
.text:0000000078B62602 4C 8D 3D 47 FE FF FF lea r15, off_78B62450
.text:0000000078B62609 4D 8B AC 24 88 14 00 00 mov r13, [r12+1488h]
.text:0000000078B62611
.text:0000000078B62611 loc_78B62611: ; CODE XREF: ;TurboDispatchJumpAddressEnd+34j
.text:0000000078B62611 41 83 A5 D0 02 00 00 01 and dword ptr [r13+2D0h], 1
.text:0000000078B62619 0F 84 AF 00 00 00 jz loc_78B626CE
.text:0000000078B6261F 41 0F 28 85 70 01 00 00 movaps xmm0, xmmword ptr [r13+170h] ;x64模式!
.text:0000000078B62627 41 0F 28 8D 80 01 00 00 movaps xmm1, xmmword ptr [r13+180h]
.text:0000000078B6262F 41 0F 28 95 90 01 00 00 movaps xmm2, xmmword ptr [r13+190h]
.text:0000000078B62637 41 0F 28 9D A0 01 00 00 movaps xmm3, xmmword ptr [r13+1A0h]
.text:0000000078B6263F 41 0F 28 A5 B0 01 00 00 movaps xmm4, xmmword ptr [r13+1B0h]
.text:0000000078B62647 41 0F 28 AD C0 01 00 00 movaps xmm5, xmmword ptr [r13+1C0h]
.text:0000000078B6264F 41 8B 8D B0 00 00 00 mov ecx, [r13+0B0h]
.text:0000000078B62656 41 8B 95 AC 00 00 00 mov edx, [r13+0ACh]
.text:0000000078B6265D 41 83 A5 D0 02 00 00 FE and dword ptr [r13+2D0h], 0FFFFFFFEh
.text:0000000078B62665 41 8B BD A0 00 00 00 mov edi, [r13+0A0h]
.text:0000000078B6266C 41 8B B5 A4 00 00 00 mov esi, [r13+0A4h]
.text:0000000078B62673 41 8B 9D A8 00 00 00 mov ebx, [r13+0A8h]
.text:0000000078B6267A 41 8B AD B8 00 00 00 mov ebp, [r13+0B8h]
.text:0000000078B62681 41 8B 85 B4 00 00 00 mov eax, [r13+0B4h]
.text:0000000078B62688 49 89 A4 24 80 14 00 00 mov [r12+1480h], rsp
.text:0000000078B62690 66 C7 44 24 08 23 00 mov [rsp+0B8h+var_B0], 23h
.text:0000000078B62697 66 C7 44 24 20 2B 00 mov [rsp+0B8h+var_98], 2Bh
.text:0000000078B6269E 45 8B 85 C4 00 00 00 mov r8d, [r13+0C4h]
.text:0000000078B626A5 41 81 A5 C4 00 00 00 FF+ and dword ptr [r13+0C4h], 0FFFFFEFFh
.text:0000000078B626B0 44 89 44 24 10 mov [rsp+0B8h+var_A8], r8d
.text:0000000078B626B5 45 8B 85 C8 00 00 00 mov r8d, [r13+0C8h]
.text:0000000078B626BC 4C 89 44 24 18 mov [rsp+0B8h+var_A0], r8
.text:0000000078B626C1 45 8B 85 BC 00 00 00 mov r8d, [r13+0BCh]
.text:0000000078B626C8 4C 89 04 24 mov [rsp+0B8h+var_B8], r8
.text:0000000078B626CC 48 CF iretq ;返回到x64
.text:0000000078B626CE ; ---------------------------------------------------------------------------
.text:0000000078B626CE
.text:0000000078B626CE loc_78B626CE: ;x86模式
.text:0000000078B626CE 41 8B BD A0 00 00 00 mov edi, [r13+0A0h]
.text:0000000078B626D5 41 8B B5 A4 00 00 00 mov esi, [r13+0A4h]
.text:0000000078B626DC 41 8B 9D A8 00 00 00 mov ebx, [r13+0A8h]
.text:0000000078B626E3 41 8B AD B8 00 00 00 mov ebp, [r13+0B8h]
.text:0000000078B626EA 41 8B 85 B4 00 00 00 mov eax, [r13+0B4h]
.text:0000000078B626F1 49 89 A4 24 80 14 00 00 mov [r12+1480h], rsp
.text:0000000078B626F9 41 C7 46 04 23 00 00 00 mov dword ptr [r14+4], 23h
.text:0000000078B62701 41 B8 2B 00 00 00 mov r8d, 2Bh
.text:0000000078B62707 41 8E D0 mov ss, r8w
.text:0000000078B6270A assume ss:nothing
.text:0000000078B6270A 41 8B A5 C8 00 00 00 mov esp, [r13+0C8h]
.text:0000000078B62711 45 8B 8D BC 00 00 00 mov r9d, [r13+0BCh]
.text:0000000078B62718 45 89 0E mov [r14], r9d
.text:0000000078B6271B 41 FF 2E jmp fword ptr [r14] ;这个大跳会切换到x86模式!
这个函数主要就是从之前获取到的context里初始化各个通用寄存器.然后根据想要模拟的CPU环境进行跳转. OK.到这里,整个大概的分发流程已经清楚了, 实现我们的需求就很简单了,模拟一次即可以了.
要执行wow64模式的shellcode,
也需要构造这些stub. 一共是2个stub
1. PsGetProcessPeb 返回的原生的PEB.
添加KeCallbackTable的entry指向我们的wow64 stub.
2. PsGetProcessWow64Process获取到wow64模式的PEB,
然后定位到相应的WOW64 KeCallbackTable ,添加entry指向需要执行的x86 shellcode. wow64模式的APC
相对来说就好多了.只有一个简单的变换
text:0000000078E9FCD0 public KiUserApcDispatcher
.text:0000000078E9FCD0 KiUserApcDispatcher: ; CODE XREF: .text:0000000078E9FD07j
.text:0000000078E9FCD0 ; DATA XREF: .rdata:off_78F58128o
.text:0000000078E9FCD0 48 8B 4C 24 18 mov rcx, [rsp+18h]
.text:0000000078E9FCD5 48 8B C1 mov rax, rcx
.text:0000000078E9FCD8 4C 8B CC mov r9, rsp
.text:0000000078E9FCDB 48 C1 F9 02 sar rcx, 2
.text:0000000078E9FCDF 48 8B 54 24 08 mov rdx, [rsp+8]
.text:0000000078E9FCE4 48 F7 D9 neg rcx
.text:0000000078E9FCE7 4C 8B 44 24 10 mov r8, [rsp+10h]
.text:0000000078E9FCEC 48 0F A4 C9 20 shld rcx, rcx, 20h
.text:0000000078E9FCF1 85 C9 test ecx, ecx
.text:0000000078E9FCF3 74 22 jz short loc_78E9FD17
.text:0000000078E9FCF5 48 8B 0C 24 mov rcx, [rsp]
.text:0000000078E9FCF9 FF D0 call rax
红色标记的地方.,ntdll64! KiUserApcDispatcher 对应我们传递的Apc例程地址做了一个小变化,我们做逆变换即可.
#ifdef _WIN64
if (bWow64)
{
//Neg rax
//shl rax,2
pFixStubAddr = (void*) NEG( (LONG)pFixStubAddr);
pFixStubAddr = (void*) SHL( (LONG)pFixStubAddr,2);
}
#endif //附相关代码片段. xSpy@BinVul.com
xSpy@Vxjump.net
20170724
排版全乱了.,传一份word版的吧 ExecShellCodeInWow64ModeFromRing0.doc
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