computational thinking

Software reverse engineering
with graph theory

Content

What is reverse engineering?
Motivations
Comparing binaries using graph theory
Credits

<< Compiling in Java

What is reverse engineering?

"Reverse engineering is the opposite

of compiling"

Convert machine code that is

closer to binary

#include <stdio.h>
int main() 
{
    printf("hello, world");

    struct person {
        int age, salary;
        DEPT department;
        char name[12];
        char address[6][20];
    };
    return 0; 
};

Source code

to source code that is human-readable

Motivations

Can the software be trusted?
Stuxnet

Took more than a year to be discovered
Took experts half a year to decipher the payload!

You can't trust code that you did not totally create yourself.

(Especially code from companies that employ people like me.)

- Ken Thompson, Turing award winner 1983

Comparing binaries using graph theory

Opportunities

Programmers are lazy
Upsurge in open source code usage
Programs have their own unique control-flow

#include <stdio.h>
int main() 
{
    printf("hello, world");
    boolean diet = false;

    if(a == false)
    {
        printf("%s\n", "eat pizza");
    }
    else
    {
        printf("%s\n", "no eating!");
    }

    return 0; 
};

example C program

#include <stdio.h>
int main() 
{
    printf("hello, world");
    boolean diet = false;

    if(diet == false)
    {
        printf("%s\n", "eat pizza");
    }
    else
    {
        printf("%s\n", "no eating!");
    }

    return 0; 
};