Otherwise, download these files into the C:\IDA folder.
When you see the IDA window shown below, click the OK button.
Click "I Agree".
In the "Welcome to IDA!" box, as shown below, click the New button.
In the "About" box, click the OK button.
In the "New disassembly database" box, click "PE Executable", and then click OK, as shown below:
In the "Select PE Executable to disassemble" box, navigate to C:\IDA\crackme-121-1.exe and double-click it.
In the "Welcome to the PE Executable file loading Wizard" box, click the Next button, as shown below:
In the "Segment Creation" box, click Next.
In the "File loading" box, click Finish.
A box pops up saying "...the input file was linked with debug information...", as shown below. Click the Yes button.
Close the "Graph Overview" box in the lower right corner.
Drag the lower border of the "View-A" pane down, to make as large a viewable area as possible.
From the IDA menu bar, click Search, Text.
Search for crackme as shown below.
Click OK.
Right-click in the "View-A" box and click "Fit window", as shown below:
You should now see the entire program shown as six boxes connected by lines, as shown below. (Ignore the two extra boxes at the upper left):
For this project, I have labelled the modules with letters as shown below:
Right-click in the "View-A" box and click "Zoom 100%", as shown below:
Click and drag the "View-A" display as needed to make module A visible, as shown below:
The assembly code is hard to read, but you don't need to understand it all. Focus on the last two instructions:
cmp [ebp+arg_0], 2
jz short loc_4113C2
This compares some number to 2 with the cmp (Compare) operation, and jumps to a different module if it is 2, using the jz (Jump if Zero) operation.
Drag the "View-A" display to make Module C visible, as show below:
Notice the gray readable text on the right side, saying "Usage: crackme-121-1 password".
This module pushes those characters onto the stack with a push command, and then calls the printf function with the call   ds:_imp_printf command.
The figure below shows the C statements that comple to the "C" module:
Follow along in IDA Pro and make sure you see what each of the six modules do, and how they correspond to the C source code.
The password "topsecret" is visible.
In the Command Prompt window, execute these commands:
cd \IDA
crackme-121-1
You should see the message
"Usage: crackme-121-1 password",
as shown below:
This message is telling you that you need to add a password after the "crackme-121-1".
In the Command Prompt window, execute this command:
crackme-121-1 wrongpassword
You should see the message
"Fail!".
In the Command Prompt window, execute this command:
crackme-121-1 topsecret
You should see the message
"You found the password!",
as shown below:
It is very similar to crackme-121-1. Use IDA Pro to find the password, and run the program with the correct password, so you see a "Congratulations" message.
Use the form below to put your name on the WINNERS PAGE.
It is very similar to crackme-121-1. Use IDA Pro to find the password, and run the program with the correct password, so you see a "Congratulations" message.
Use the form below to put your name on the WINNERS PAGE.
Use the form below to put your name on the WINNERS PAGE.