VirtualProtect和kernel32.dll - 尝试访问无效地址

Question

我正在分析流程加载的各种模块.不幸的是,我无法创建kernel32.dll内存快照,尽管该功能可以与其他模块正常工作(例如ntddl.dll).问题出在以下代码中:

/* Copy code from memory  */
if (VirtualProtect((BYTE*)virtualAddress, sizeOfCode, PAGE_EXECUTE_READWRITE, &flags) == 0) {
    std::cout << "VirtualProtect failed!" << std::endl;
    std::cout << "Virtual address: " << virtualAddress << std::endl;
    std::cout << "Size of code: " << sizeOfCode << std::endl;
    std::cout << "Error code: " << GetLastError() << std::endl;
}

调用此代码的结果kernel32.dll是:

Virtual address: 747d0000
Size of code: 6a000
Error code: 0x1e7

错误描述说:

ERROR_INVALID_ADDRESS
487 (0x1E7)
Attempt to access invalid address. 

我检查了进程'内存映射和kernel32.dll地址是否正确.原因是什么？

Answer 1

很难确认你的地址是否正确,它非常低.我刚刚编写了另一个程序来测试它.它枚举kernel32.dll中的区域并在其上调用VirtualProtect():

#include <Windows.h>
#include <assert.h>
#include <iostream>


int main()
{
    HMODULE hmod = GetModuleHandle(L"kernel32.dll");
    MEMORY_BASIC_INFORMATION info;
    // Start at PE32 header
    SIZE_T len = VirtualQuery(hmod, &info, sizeof(info));
    assert(len > 0);
    BYTE* dllBase = (BYTE*)info.AllocationBase;
    BYTE* address = dllBase;
    for (;;) {
        len = VirtualQuery(address, &info, sizeof(info));
        assert(len > 0);
        if (info.AllocationBase != dllBase) break;
        std::cout << "Address: " << std::hex << info.BaseAddress;
        std::cout << " (" << std::hex << info.RegionSize << ") ";
        std::cout << " protect = " << std::hex << info.Protect;
        DWORD oldprotect;
        if (info.Protect == 0) std::cout << ", VirtualProtect skipped" << std::endl;
        else {
            BOOL ok = VirtualProtect(info.BaseAddress, info.RegionSize, PAGE_EXECUTE_READWRITE, &oldprotect);
            std::cout << ", VirtualProtect = " << (ok ? "okay" : "Failed!") << std::endl;
        }
        address = (BYTE*)info.BaseAddress + info.RegionSize;
    }
    return 0;
}

在我的机器上输出此程序,运行Windows 8.1 x64:

Address: 77470000 (1000)  protect = 2, VirtualProtect = okay
Address: 77471000 (f000)  protect = 0, VirtualProtect skipped
Address: 77480000 (62000)  protect = 20, VirtualProtect = okay
Address: 774E2000 (e000)  protect = 0, VirtualProtect skipped
Address: 774F0000 (7e000)  protect = 2, VirtualProtect = okay
Address: 7756E000 (2000)  protect = 0, VirtualProtect skipped
Address: 77570000 (1000)  protect = 4, VirtualProtect = okay
Address: 77571000 (f000)  protect = 0, VirtualProtect skipped
Address: 77580000 (1000)  protect = 2, VirtualProtect = okay
Address: 77581000 (f000)  protect = 0, VirtualProtect skipped
Address: 77590000 (1a000)  protect = 2, VirtualProtect = okay
Address: 775AA000 (6000)  protect = 0, VirtualProtect skipped

以64位模式运行:

Address: 00007FFC4F870000 (1000)  protect = 2, VirtualProtect = okay
Address: 00007FFC4F871000 (112000)  protect = 20, VirtualProtect = okay
Address: 00007FFC4F983000 (1000)  protect = 4, VirtualProtect = okay
Address: 00007FFC4F984000 (1000)  protect = 8, VirtualProtect = okay
Address: 00007FFC4F985000 (24000)  protect = 2, VirtualProtect = okay

显然,您有不同的Windows版本,因此请务必在您的计算机上运行此程序以获得可比较的结果.

我得出的结论是,这种代码失败没有根本原因.如果它在您的机器上,那么这可能是环境的.有一个非常明显的候选者是你的反恶意软件软件,当然在防止代码搞乱kernel32.dll方面有很大的利害关系.我在我的机器上运行最小的保护.