Cracking .NET apps

Last time we had an opportunity to review few crackmes solutions. This time we will check how to solve crackme created in .NET. Here we go...

Example crackmes you can find here or here. I decided to use the same environmet I used last time so I think we are ready to go.

To solve this crackme we will use dnSpy (few details are also available here).

Let's open the file - CrackMe2.exe - created by timeleg86:

Using the left pane we can see the Form1 and it's content - button1_Click() function:

I decided to set a breakpoint (F9) before the if() statement, like this:

Now, run the app (F5), we should be in our breakpoint (before if-statement). Right-click to choose editor:

We are here:

As you can see I added a little change in line 14, now click 'Compile' button and go to the File->SaveAll...

I used the name CrackMe2-b.exe to save our new file. Run and check it again:

Hurray, we save the world again! ;)

Comments/questions? Drop me a message.


Cheers,
Cody