Baby RE

Author: Xh4H
Category: Reversing
Points: 10

Challenge Description

Show us your basic skills! (P.S. There are 4 ways to solve this, are you willing to try them all?)\

baby

Approach

I have yet to find all four ways to solve it but will add if I do. Open baby with Ghidra and navigate to the main function.

undefined8 main(void)

{
  int iVar1;
  undefined8 local_48;
  undefined8 local_40;
  undefined4 local_38;
  undefined2 local_34;
  char local_28 [24];
  char *local_10;
  
  local_10 = "Dont run `strings` on this challenge, that is not the way!!!!";
  puts("Insert key: ");
  fgets(local_28,0x14,stdin);
  iVar1 = strcmp(local_28,"abcde122313\n");
  if (iVar1 == 0) {
    local_48 = 0x594234427b425448;
    local_40 = 0x3448545f5633525f;
    local_38 = 0x455f5354;
    local_34 = 0x7d5a;
    puts((char *)&local_48);
  }
  else {
    puts("Try again later.");
  }
  return 0;
}

Method 1

The first method is simply running it. We see the line iVar1 = strcmp(local_28,"abcde122313\n"); meaning we need our input to equal to "abcde122313" and a new line character.

$ ./baby
Insert key:
abcde122313
HTB{B4BY_R3V_TH4TS_EZ}

Method 2

The second method is noticing the hex:

if (iVar1 == 0) {
  local_48 = 0x594234427b425448;
  local_40 = 0x3448545f5633525f;
  local_38 = 0x455f5354;
  local_34 = 0x7d5a;
  puts((char *)&local_48);
}

These are in little endian so we can start from local_34 and decode up to local_48. this gives us "}ZE_ST4HT_V3R_YB4B{BTH" which we can reverse and get the flag.

print("}ZE_ST4HT_V3R_YB4B{BTH"[::-1])

Flag

HTB{B4BY_R3V_TH4TS_EZ}