timer.md

timer

Overview

100 points

Category: Reverse Engineering

Tags : #android #apk #strings

Description

You will find the flag after analysing this apk.

Solution

An android .apk file is a zip bundle, therefore unzipping and initially searching for the expected flag string locates the file to display the strings for.

$ unzip timer.apk

$ grep -rw picoCTF .
  grep: ./classes3.dex: binary file matches

$ strings -t x classes3.dex | grep picoCTF
  160f *picoCTF{........redacted........}

Actual flag value redacted for the purposes of the write up.