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一直好奇将一个进程的所有线程的线程标志改成Terminated后,这个进程会自动结束吗?还是这个进程只是被设置成了结束标志,而实际还在运行?想写个程序试验一下,但问题来了,怎么得到线程的标志呢?在PsIsSystemThread中得到线程的是否为系统线程的标志win xp 下的ntoskrnl.exe文件中的PsIsSystemThread的函数:; Attributes: bp-based frame; __stdcall PsIsSystemThread(x)public _PsIsSystemThread@4_PsIsSystemThread@4 proc neararg_0= dword ptr 8mov edi, edi ; IoIsSystemThreadpush ebpmov ebp, espmov eax, [ebp+arg_0]mov eax, [eax+248h]shr eax, 4and al, 1pop ebpretn 4_PsIsSystemThread@4 endpF5一下下:char __stdcall PsIsSystemThread(int a1){ return (*(_DWORD *)(a1 + 0x248) >> 4) & 1;}比较下面来自官方的声明PsIsSystemThread routineThePsIsSystemThreadroutine checks whether a given thread is a system thread.SyntaxC++BOOLEAN PsIsSystemThread(
_In_PETHREAD Thread
);
ParametersThread[in]Pointer to the thread to be checked.Return valuePsIsSystemThreadreturnsTRUEif the specified thread is a system thread,FALSEotherwise.来源:<http://msdn.microsoft.com/zh-cn/library/ff559945(v=vs.85).aspx>可以猜测a1 + 0x248就是线程权限的标识。我们在xp系统上看一下:nt!_ETHREAD +0x000 Tcb : _KTHREAD +0x1c0 CreateTime : _LARGE_INTEGER +0x1c0 NestedFaultCount : Pos 0, 2 Bits +0x1c0 ApcNeeded : Pos 2, 1 Bit +0x1c8 ExitTime : _LARGE_INTEGER +0x1c8 LpcReplyChain : _LIST_ENTRY +0x1c8 KeyedWaitChain : _LIST_ENTRY +0x1d0 ExitStatus : Int4B +0x1d0 OfsChain : Ptr32 Void +0x1d4 PostBlockList : _LIST_ENTRY +0x1dc TerminationPort : Ptr32 _TERMINATION_PORT +0x1dc ReaperLink : Ptr32 _ETHREAD +0x1dc KeyedWaitValue : Ptr32 Void +0x1e0 ActiveTimerListLock : Uint4B +0x1e4 ActiveTimerListHead : _LIST_ENTRY +0x1ec Cid : _CLIENT_ID +0x1f4 LpcReplySemaphore : _KSEMAPHORE +0x1f4 KeyedWaitSemaphore : _KSEMAPHORE +0x208 LpcReplyMessage : Ptr32 Void +0x208 LpcWaitingOnPort : Ptr32 Void +0x20c ImpersonationInfo : Ptr32 _PS_IMPERSONATION_INFORMATION +0x210 IrpList : _LIST_ENTRY +0x218 TopLevelIrp : Uint4B +0x21c DeviceToVerify : Ptr32 _DEVICE_OBJECT +0x220 ThreadsProcess : Ptr32 _EPROCESS +0x224 StartAddress : Ptr32 Void +0x228 Win32StartAddress : Ptr32 Void +0x228 LpcReceivedMessageId : Uint4B +0x22c ThreadListEntry : _LIST_ENTRY +0x234 RundownProtect : _EX_RUNDOWN_REF +0x238 ThreadLock : _EX_PUSH_LOCK +0x23c LpcReplyMessageId : Uint4B +0x240 ReadClusterSize : Uint4B +0x244 GrantedAccess : Uint4B +0x248 CrossThreadFlags : Uint4B +0x248 Terminated : Pos 0, 1 Bit +0x248 DeadThread : Pos 1, 1 Bit +0x248 HideFromDebugger : Pos 2, 1 Bit +0x248 ActiveImpersonationInfo : Pos 3, 1 Bit +0x248 SystemThread : Pos 4, 1 Bit +0x248 HardErrorsAreDisabled : Pos 5, 1 Bit +0x248 BreakOnTermination : Pos 6, 1 Bit +0x248 SkipCreationMsg : Pos 7, 1 Bit +0x248 SkipTerminationMsg : Pos 8, 1 Bit +0x24c SameThreadPassiveFlags : Uint4B +0x24c ActiveExWorker : Pos 0, 1 Bit +0x24c ExWorkerCanWaitUser : Pos 1, 1 Bit +0x24c MemoryMaker : Pos 2, 1 Bit +0x250 SameThreadApcFlags : Uint4B +0x250 LpcReceivedMsgIdValid : Pos 0, 1 Bit +0x250 LpcExitThreadCalled : Pos 1, 1 Bit +0x250 AddressSpaceOwner : Pos 2, 1 Bit +0x254 ForwardClusterOnly : UChar +0x255 DisablePageFaultClustering : UChar果然,那么我们可以通过在PsIsSystemThread函数中查找特征码的方法来取得线程的标识。如果要保护进程,我们可以将进程的所有线程的线程标志都设置成SystemThread。1. PsIsSystemThread是导出但未声明的函数,只需要声明一下就可以使用了。声明:BOOLEAN PsIsSystemThread( _In_ PETHREAD Thread);
蓝屏原因:机器上PsIsSystemThread函数的地址并不是函数的真实地址,而是jmp指令,指令的目的地才地函数的真实地址。f8be2520 ff251826bef8 jmp dword ptr ds:[0F8BE2618h]问题来了,之一:为什么得到的函数地址不是真实地址,是系统本身就是JMP样子的还是被机器上的安全软件给修改成JMP的?验证方法:回复快照,看最原始的系统中这个地方是不是也是JMP?在干净的系统上,uf函数总是能看到真正的地址:lkd> uf PsIsSystemThreadnt!IoIsSystemThread:804ef8a2 8bff mov edi,edi804ef8a4 55 push ebp804ef8a5 8bec mov ebp,esp804ef8a7 8b4508 mov eax,dword ptr [ebp+8]804ef8aa 8b8048020000 mov eax,dword ptr [eax+248h]804ef8b0 c1e804 shr eax,4804ef8b3 2401 and al,1804ef8b5 5d pop ebp804ef8b6 c20400 ret 4而在程序中看到的都是JMP地址:BOOLEAN PsIsSystemThread(PETHREAD Thread);dprintf("PsIsSystemThread:0X%08X\n", (PULONG)pPsIsSystemThread);看来系统本身就是JMP地址。通过x nt!PsIsSystemThread看看结果,得到函数真实地址,函数真实地址的地方是不是FF 25而函数的真实地址是804ef8a2lkd> uf PsIsSystemThreadnt!IoIsSystemThread:804ef8a2 8bff mov edi,edi804ef8a4 55 push ebp804ef8a5 8bec mov ebp,esp804ef8a7 8b4508 mov eax,dword ptr [ebp+8]804ef8aa 8b8048020000 mov eax,dword ptr [eax+248h]804ef8b0 c1e804 shr eax,4804ef8b3 2401 and al,1804ef8b5 5d pop ebp804ef8b6 c20400 ret 4而程序得到的地址为JMP地址BOOLEAN PsIsSystemThread(PETHREAD Thread);BOOLEAN IoIsSystemThread(PETHREAD Thread);dprintf("PsIsSystemThread:0X%08X\n", (PULONG)pPsIsSystemThread);dprintf("IoIsSystemThread:0X%08X\n", (PULONG)pIoIsSystemThread);
这两个函数的地址分别为:PsIsSystemThread:0XF8C2055CIoIsSystemThread:0XF8C20550lkd> u 0xf8c2055cf8c2055c ff259c06c2f8 jmp dword ptr ds:[0F8C2069Ch]f8c20562 cc int 3f8c20563 cc int 3f8c20564 cc int 3f8c20565 cc int 3f8c20566 cc int 3f8c20567 cc int 3f8c20568 ff25a806c2f8 jmp dword ptr ds:[0F8C206A8h]lkd> u f8c20550f8c20550 ff259806c2f8 jmp dword ptr ds:[0F8C20698h]f8c20556 cc int 3f8c20557 cc int 3f8c20558 cc int 3f8c20559 cc int 3f8c2055a cc int 3f8c2055b cc int 3f8c2055c ff259c06c2f8 jmp dword ptr ds:[0F8C2069Ch] dword ptr ds:[0F8C2069Ch] = dword ptr ds:[0F8C20698h] = 804ef8a2 http://bbs.pediy.com/showthread.php?t=93742这里的代码好像没有处理FF25所以看雪上楼主的这个程序会蓝屏。改后代码:ULONG GetCrossThreadFlagOffset(){ ULONG Offset = 0; PUCHAR pPsIsSystemThread; PULONG pFuncAddr; PUCHAR pFeature; if(Offset == 0) { pPsIsSystemThread = (PUCHAR)PsIsSystemThread; } dprintf("PsIsSystemThread:0X%08X\n", (PULONG)pPsIsSystemThread); //判断是不是FF 25 if ((*pPsIsSystemThread) != 0xFF || *(pPsIsSystemThread+1) != 0X25) { dprintf("pProc is not ff 25.\n"); return Offset; } //ff25 9806c2f8 jmp dword ptr ds:[0F8C20698h] pFuncAddr = (*(PULONG)(pPsIsSystemThread+2)); dprintf("pFuncAddr:0X%08X\n", (PULONG)pFuncAddr); pFuncAddr = (PULONG)*pFuncAddr; dprintf("pFuncAddr:0X%08X\n", (PULONG)pFuncAddr); pFeature = (PUCHAR)pFuncAddr; while( *pFeature!=0x8B || *(pFeature+1)!=0x80 ) pFeature++; dprintf("Instruction found in address:0X%08X\n",(PULONG)pFeature); Offset = *(PULONG)(pFeature+2); dprintf("Offset:0X%08X\n",Offset); return Offset; } |
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