Tag: android

Reversing for fun thanks to intelligence service

Capture The Flag, or CTF for short, always are a good opportunity to challenge its knowledge and capabilities about software security. This year again, the DGSE (Directorate General for External Security, the French foreign intelligence services) and Telecom SudParis school teamed up to create the 404 CFT: a free-to-join online CTF. I decided to give it a try to check how my reverse engineering skills aged.

I tackled the Android reverse engineering challenge. It was split in two parts: Bugdroid Fight [1/2], rated as easy I won’t detail here, and Bugdroid Fight [2/2] rated as average difficulty (the second of the four difficulty levels before hard and extreme) I will walk through in this post. The goal for a CTF challenge is to find a flag: like an hidden text or a password. Running the application inside an emulator quickly gives how to find the flag: you have to find the text that validates the application form.

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Android for left handed

Guess what? I’m left handed! And I’m sad to see that Google is still not offering a left handed option to theirs users. Until now, one solution is to use a custom rom witch allows you to customize navigation bar. But with the recent Lollipop release, no custom rom is yet ready for daily use… Moreover, ART, the new runtime, breaks Xposed Framework compatibility. Xposed Framework was another solution for stock rooted rom to install a module for navigation bar customization. I recently bought a Nexus 6 (still shipping!) and I don’t want to wait a new solution (Xposed Framework compatibility is not coming soon). Never mind, I’m a developer so let’s do this myself!

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Time4Popcorn for Android

This week was released an Android version of Popcorn Time. For those who don’t know the project, it’s similar to Netflix: you select the movie or serie you want to watch and could instantly play it. Unlike Netflix, it’s free, based on user torrent seed and illegal in almost all countries. So don’t use it and go buy you DVD instead !

Existing versions still confine to desktop releases until now. So be happy mobile users, you day is coming ! Except one thing (or two, which career will allow you to download 1080p movie with p2p ?), it’s not the official / legacy team of Popcorn Time which releases the application. What does it means ? An alternative team is releasing the same software under an alternate name « Time4Popcorn ». But what for ?

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Air Playit and IPv6

Air PlayitI was looking for a way to stream my desktop videos to my N7 when I discovered Air Playit.

Despite it well well finished website, the Android application is really painful. From the first steps, the app forces close. Don’t think to use auto discovery to find your airplay server without crash. And add manually a server ? Crash also.

I grabbed an USB plug to check logcat and I saw NullPointerException on String manipulation. A NPE causing app crash ? The start of pain… A quick look into smali code confirmed my thoughts: the app tried to split an IPv6 with  « . » (dot) separator… Quick fixing (in smali), recompilating and packing to skip IPv6 allowed me to add manually a server. I have at last listed my movies on my N7.

Hopeful, I tried to read a stream a content. No way. Still blank screen with audio. And without app source, I don’t have the courage to fix the software decoder… (and why the app does not use Intent to use my media reader instead of the crappy embedded one ?). Damn.

The pain continues with the ugly GUI (why use so many resources to get iOS look and feel on Android ?), the crash when failing the SD card detection (whereas Google discourage manufactors to add them to new device) and the developer team which does not answer to the fourteen pages of users complaining about app crash.

Finally, I use Windows sharings, Solid Explorer (with Samba) and MX player (with hardware stream decoder). It works, does not load my computer with encoding and save my batery. What else ?