枚举进程句柄，奇怪的问题

Posted 2021-05-03

我扫描打开的句柄到我的进程并在控制台中打印它们。

1. 我开始我的过程
2. 我附上作弊引擎
3. 我运行打开句柄的枚举
4. 我看到哪个进程有我的进程句柄

此时奇怪的问题如下，检查代码：

array<Accessor^>^ AntiCheat::ScanHandles()
{
    List<Accessor^>^ accessorList = gcnew List<Accessor^>();

    if (!EnableDebugPrivilege(true))
        printf("EnableDebugPrivilege failed: %d
", GetLastError());

    tNtQuerySystemInformation oNtQuerySystemInformation = (tNtQuerySystemInformation)GetProcAddress(GetModuleHandle("ntdll.dll"), "NtQuerySystemInformation");

    PSYSTEM_HANDLE_INFORMATION handleInfo = new SYSTEM_HANDLE_INFORMATION;
    SYSTEM_INFORMATION_CLASS infoClass = (SYSTEM_INFORMATION_CLASS)16; // SystemHandleInformation
    DWORD size = sizeof(SYSTEM_HANDLE_INFORMATION);
    DWORD needed = 0;
    NTSTATUS status = oNtQuerySystemInformation(infoClass, handleInfo, size, &needed);
    while (!NT_SUCCESS(status))
    {
        if (needed == 0)
            return nullptr;
        // The previously supplied buffer wasn't enough.
        delete handleInfo;
        size = needed + 1024;
        handleInfo = (PSYSTEM_HANDLE_INFORMATION)new BYTE[size];
        status = oNtQuerySystemInformation(infoClass, handleInfo, size, &needed);
    }

    HANDLE currentProcess = GetCurrentProcess();
    DWORD currentProcessId = GetProcessId(currentProcess);
    for (DWORD i = 0; i < handleInfo->dwCount; i++)
    {
        //printf(".");
        SYSTEM_HANDLE handle = handleInfo->Handles[i];

        HANDLE procHandle = OpenProcess(PROCESS_DUP_HANDLE | PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, false, handle.dwProcessId);
        if (GetLastError() == ERROR_ACCESS_DENIED)
            continue;

        HANDLE dupl = 0;
        if (!DuplicateHandle(procHandle, (HANDLE)handle.wValue, currentProcess, &dupl, 0, false, DUPLICATE_SAME_ACCESS))
            continue;

        DWORD procId = GetProcessId(dupl);
        if (procId == currentProcessId)
        {
            printf("accessing us
");
            char processName[MAX_PATH];
            GetModuleFileNameEx((HMODULE)procHandle, NULL, processName, MAX_PATH);
            accessorList->Add(gcnew Accessor(gcnew String(processName), handle.GrantedAccess));
        }

        CloseHandle(dupl);
    }

    return accessorList->ToArray();
}

如果我用printf（“。”）;取消注释该行，我会看到3个打开的句柄到我的进程（cheatengine）。如果它被评论（运行方式更快），则没有打开的句柄。但是我不知道为什么这会影响我的代码。我很惊讶，有谁知道为什么会这样？或者如何找到如何在没有我的printf（“。”）的情况下找到句柄;线？

另一个问题是：每次调用函数时，分配的字节数都会重复。我不知道为什么。

答案

我发现你的代码存在逻辑问题。

您不会忽略handle.dwProcessId等于currentProcessId的数组项，因此您最终会打开自己进程的句柄。由于您只对寻找其他过程感兴趣，因此您应该忽略handle.dwProcessId等于currentProcessId的项目。

您没有检查OpenProcess()是否因ERROR_ACCESS_DENIED以外的任何原因而失败。除非GetLastError()实际上首先返回NULL，否则不要调用OpenProcess()。

如果DuplicateHandle()失败，你不会关闭一个打开的句柄。为什么要复制每个源句柄只是为了调用它上面的GetProcessId()？你已经从数组中获得了他们的进程ID，因此整个DuplicateHandle() + GetProcessId()是完全没必要的。

无论如何，你采取了错误的方法。看看这个讨论：

Enumerating the processes referencing an object

使用NtQuerySystemInformation和SystemInformationClass设置为SystemHandleInformation。这将填充SYSTEM_HANDLE_INFORMATION结构数组，其定义如下：

typedef struct _SYSTEM_HANDLE_INFORMATION {
    ULONG ProcessId;
    UCHAR ObjectTypeNumber;
    UCHAR Flags;
    USHORT Handle;
    PVOID Object;
    ACCESS_MASK GrantedAccess;
 } SYSTEM_HANDLE_INFORMATION;

使用ProcessID等于GetCurrentProcessId（）搜索与您打开的句柄对应的条目，然后查找具有相同Object指针的所有条目。

虽然讨论显示SYSTEM_HANDLE_INFORMATION的错误声明。以下文章显示了正确的一个：

HOWTO: Enumerate handles

#define SystemHandleInformation 16

typedef NTSTATUS (NTAPI *_NtQuerySystemInformation)(
    ULONG SystemInformationClass,
    PVOID SystemInformation,
    ULONG SystemInformationLength,
    PULONG ReturnLength
    );

/* The following structure is actually called SYSTEM_HANDLE_TABLE_ENTRY_INFO, but SYSTEM_HANDLE is shorter. */
typedef struct _SYSTEM_HANDLE
{
    ULONG ProcessId;
    BYTE ObjectTypeNumber;
    BYTE Flags;
    USHORT Handle;
    PVOID Object;
    ACCESS_MASK GrantedAccess;
 } SYSTEM_HANDLE, *PSYSTEM_HANDLE;

typedef struct _SYSTEM_HANDLE_INFORMATION
{
  ULONG HandleCount; /* Or NumberOfHandles if you prefer. */
  SYSTEM_HANDLE Handles[1];
} SYSTEM_HANDLE_INFORMATION, *PSYSTEM_HANDLE_INFORMATION;

话虽如此，尝试更像这样的东西：

array<Accessor^>^ AntiCheat::ScanHandles()
{
    List<Accessor^>^ accessorList = gcnew List<Accessor^>();

    if (!EnableDebugPrivilege(true))
        printf("EnableDebugPrivilege failed: %d
", GetLastError());

    tNtQuerySystemInformation oNtQuerySystemInformation = (tNtQuerySystemInformation) GetProcAddress(GetModuleHandle("ntdll.dll"), "NtQuerySystemInformation");

    DWORD currentProcessId = GetCurrentProcessId();
    HANDLE currentProcess = OpenProcess(PROCESS_ALL_ACCESS, FALSE, currentProcessId);
    PVOID currentProcessAddr = nullptr;

    DWORD size = sizeof(SYSTEM_HANDLE_INFORMATION);
    DWORD needed = 0;
    PSYSTEM_HANDLE_INFORMATION handleInfo = (PSYSTEM_HANDLE_INFORMATION) new BYTE[size];
    SYSTEM_INFORMATION_CLASS infoClass = (SYSTEM_INFORMATION_CLASS) 16; // SystemHandleInformation
    NTSTATUS status = oNtQuerySystemInformation(infoClass, handleInfo, size, &needed);
    while (status == STATUS_INFO_LENGTH_MISMATCH)
    {
        // The previously supplied buffer wasn't enough.
        delete[] handleInfo;
        size += 1024;
        handleInfo = (PSYSTEM_HANDLE_INFORMATION) new BYTE[size];
        status = oNtQuerySystemInformation(infoClass, handleInfo, size, &needed);
    }
    if (status != 0)
    {
        delete[] handleInfo;
        return nullptr;
    }    


    for (DWORD i = 0; i < handleInfo->dwCount; i++)
    {
        SYSTEM_HANDLE &handle = handleInfo->Handles[i];

        if ((handle.dwProcessId == currentProcessId) &&
            (currentProcess == (HANDLE)handle.wValue))
        {
            currentProcessAddr = handle.pAddress;
            break;
        }
    }

    for (DWORD i = 0; i < handleInfo->dwCount; i++)
    {
        SYSTEM_HANDLE &handle = handleInfo->Handles[i];

        if ((handle.dwProcessId != currentProcessId) &&
            (handle.pAddress == currentProcessAddr))
        {
            printf("accessing us
");

            HANDLE procHandle = OpenProcess(PROCESS_QUERY_INFORMATION | PROCESS_VM_READ, false, handle.dwProcessId);
            if (procHandle != 0)
            {
                char processName[MAX_PATH+1];
                DWORD len = GetModuleFileNameEx((HMODULE)procHandle, NULL, processName, MAX_PATH);
                CloseHandle(procHandle);
                processName[len] = '';
                accessorList->Add(gcnew Accessor(gcnew String(processName), handle.GrantedAccess));
            }
            else
                accessorList->Add(gcnew Accessor(gcnew String("unknown"), handle.GrantedAccess));
        }
    }

    CloseHandle(currentProcess);

    delete[] handleInfo;
    return accessorList->ToArray();
}