Easy Live

Basic Android RE 1

10 points

305 Solves

Reverse Engineering


jonp ctflearn++ badge

Community Rating: 4.57 / 5

A simple APK, reverse engineer the logic, recreate the flag, and submit!

First 10 Solvers

Rank Username
6 Krzyychuu
7 XhonC
8 s10th
9 ebouteillon
10 playerone

  • TheSuperFlight ctflearn++ badge

    Never did reverse engineering before, but i enjoyed this a lot!

    • jonp ctflearn++ badge

      Glad to hear it! Hoping to do a few more that will build on this one :)

  • keteik

    I got "Succes! CTFlearn(_is_not_secure!}" and don't now what to do next, any hints?

    • Sam_S

      read that entire program you will get it!!!!

    • jonp ctflearn++ badge

      Hey Keteik, as Sam_S mentions this is not the whole string. Carefully read over the function you found that in and see if you can understand the logic there.

  • Sam_S

    Great! Learned a lot about grep

    • jonp ctflearn++ badge

      I have provide a comment with a link that can help with this. Regarding hashcat though you may find success by grabbing the https://weakpass.com/wordlist . Though sadly it is quite large if you dont do cracking very often.

  • jonp ctflearn++ badge

    Ive been told by a number of users that they have had issues with the md5 portion of this challenge. As cracking it was not the focus point I have provided a link below to a website that will successfully decrypt it.


  • camus_

    I don't know where to start. how should I go about reverse engineering it? P.S : I'm not asking for flag or solution.

    • jonp ctflearn++ badge

      Hello camus_,

      Java (the language android apps are built in) has the near unique property of being reversible to almost the exact code it was built from. As such a good place to begin on challenges like this one are to decompile the app into a human readable form. I prefer Jadx-gui on a Kali linux install but there are also some online decompilers like this one http://www.javadecompilers.com/apk

      • camus_

        hey! thanks a lot for helping. finally the challenge. It was nice experience :)

        • jonp ctflearn++ badge

          AWESOME! Glad you enjoyed it.

  • IndoXblackHT


    [REDACTED] This comment is only shown to users who have solved this challenge.

  • V1L3N

    My first RE challenge, took me a lot of time and help but still it was fun to solve!

  • c0conut

    First time trying to deal with a RE task. A nice task for beginner!

  • bt7274

    This is a good one. You can use apktool on linux, but use it only if you are a little familiar with assembly. Otherwise use one of the online tools mentioned in the comment.

  • rokka

    Nice. Great fun! Thank you!