Reverse Engineering Series — 4 (crackme)

Hi Squad,

Today we are going to look at a few easy crackme challenges.

Challenge 1

Challenge file: https://crackmes.one/static/crackme/5ed0584b33c5d449d91ae67b.zip

As we could see in IDA PRO, it is reading from the input and comparing it with “mrmtg”. Hence, the name is “mrmtg”.

We see similar logic in Ghidra as well.

Challenge 2

File: https://crackmes.one/static/crackme/632cf67b33c5d4425e2cd501.zip

we can see in IDA PRO that the value it is comparing against is “8675309\n”

Challenge 3

file: https://crackmes.one/static/crackme/5c8d45c333c5d4776a837ec2.zip

I have added the comments on the assembly.

Algorithm:

1. get a user input
2. find the decimal value of all the ascii input and sum it.
3. sum of all input chr * length of input ^ 2= 52650

if we solve this, we can get the key.

Example Key: BN!A+|NJY

Please give me a clap if you found it to be useful and follow me to get more hacking knowledge.