riceteacatpanda.wtf 1/2019

What's the Password: Revisited

1. Analyze

• As usual, i put that file into IDA and read it.
  

• Like another CTF, the first challenge is easy.

• Line 10: a copy of "off_201670" is "v5", "v5" is "rtcp{".

• Line 13: in address "v5 + 5", 8 character from "src" is added. Now, "v5" is equal to "rtcp{fL492_r_".

• Next, user input is save as "input" (v6). And i saw a loop changing the "input".

• The loop said that if my changed input is equal to byte_201020, it's a right password.

byte_201020

• By selecting and decoding, I found the last part of the flag.

Flag: rtcp{fL492_r_50m371m32_5Pr34D_0U7}