cyber-security-resources/buffer_overflow_example

Buffer Overflow Example

This is an example of a very bad coding practices that introduces a buffer overflow. The purpose of this code is to serve as a demonstration and exercise for The Art of Hacking Series and live training

#include <stdio.h>

void secretFunction()
{
    printf("Omar's Crappy Function\n");
    printf("This is a super secret function!\n");
}

void echo()
{
    char buffer[20];

    printf("Please enter your name:\n");
    scanf("%s", buffer);
    printf("You entered: %s\n", buffer);    
}

int main()
{
    echo();

    return 0;
}

The char buffer[20]; is a really bad idea. The rest will be demonstrated in the course.

You can compile this code or use the already-compiled binary here.

For 32 bit systems you can use gcc as shown below:

gcc vuln.c -o vuln -fno-stack-protector

For 64 bit systems

gcc vuln.c -o vuln -fno-stack-protector -m32

-fno-stack-protector disabled the stack protection. Smashing the stack is now allowed. -m32 made sure that the compiled binary is 32 bit. You may need to install some additional libraries to compile 32 bit binaries on 64 bit machines.