https://crackmes.one/crackme/5da31ebc33c5d46f00e2c661

Download and unzip the file (pw : crackmes.one)

Use the file command determine what kind of file it is.

Execute the file.

Use the strings command to display printable strings in [file(s)] (stdin by default)

Start up Ghidra and analyze the file. Search for the main function in Symbol tree.

local_14 = input

iVarl = input will be save to this variable

validate_key = function use to check the right input

Let’s analyze the validate_key function.

param_1 = local_14 = input

0x4c7 (HEX) = 1223 (Decimal)

validate_key(param_1) 
 {
           return praram_1 % 1223 == 0;
}

Key will be 1223 , or any multiple of 1223 , or 0

Let’s test out the key.