• we’re given what seems to be a binary file that we need to reverse engineer.

• first, let’s interact with the service we’re given.

• We can use netcat to connect to remote service.

• The service generates us a random number or outputs wrong option if anything else than 1 is sent as input.

• Below, I’ve opened the file we’re given in ghidra.

• The program seems to generate and print a random number by calling the rand() function when value 1 is used as input.

• Otherwise, it prints wrong option on the screen.

• But in between this if-else, we have a else-if condition that compares our input with 0x539.

• If the values are equal, we see that the FLAG environment table is retrieved and printed.

• As a reference, I have highlighted this in the image above. 0x539 in hexa is 1337 in decimal.

• When we introduce this value as input, we receive the flag.

FLAG : flag{l3{REDATCTED}ag}