How to hack the virtual table?

Question

I would like to know how to change the address of Test which is in the virtual table with that of HackedVTable.

void HackedVtable()
{
           


        

Answer 1

I don't think there is a portable way. Mostly because of compiler optimization and different architecture ABI between every target.

But C++ provides you with that exact same capability, why not use it?

void HackedVtable()
{
    cout << "Hacked V-Table" << endl;
}

class Base
{
public:
       virtual Test()  { cout <<"base";    }
       virtual Test1() { cout << "Test 1"; }
       void *prt;
       Base(){}
};

class Derived : public Base
{
    public: 
           Test() 
           {
                HackedVtable(); // <-- NOTE
           }
};

int main()
{
    Derived b1; // <-- NOTE

    b1.Test();

    return 0;
}