Learning Penetration Testing with Python

Understanding basic buffer overflow

The following C code lacks appropriate bound checking to enforce variable size restrictions on a copy. This is a rudimentary example of poor programming, but it is the basis for many exploits that are part of the Metasploit framework.

#include <string.h>
#include <stdio.h>
int main (int argc, char *argv[])
{
    if (argc!=2) return 1; 
    char copyto[12];
    strcpy(copyto, argv[1]);  // failure to enforce size restrictions
    printf("The username you provided is %s", copyto);
    return 0;
}

We take this code and place it into a file called username_test.cpp, and then compile it with MinGW, as shown following:

We can then run newly ...