Preloading Linux binaries

Using LD_PRELOAD to exploit/reverse binaries was presented to me in 2006. Below I will show you a very basic usage for some small example found online. Here we go...

Today we'll start here:

When I was looking for some 'nice example' I found this page. I decided to use the sample code available there, so we should start from here:

Compiling and running the code shoule present similar results as it was described on the post:

 

Code for our COMPILER.sh looks like this:

Now we should be able to continue with some other example. This one I found here:

As you can see, this time we'll attack a function strcmp(). Our super-evil-shared-library is presented below:

Let's compile it again (using our bash-compiler script) and let's see the results:

 

Now with our library loaded before the target_binary will start - we can control interesting function(s) - for this case, now we are able to present the password we are looking for. Checking results again:

As you can see - using LD_PRELOAD - we found the valid password. ;)

Now let's think for a while how it can be used to solve crackmes (or reverse malwares)...? ;)


See you next time!



Special thanks goes to my Patreon: Daniel.
You are AWESOME! ;)


Cheers