Google CTF Quals 2018 - Shall We Play A Game?

Android APK Reversing

General problem description Win the game 1,000,000 times to get the flag. For this challenge we got an .apk file, which we should apperently run and win 1,000,000 times. We let the online Java-decompiler at http://www.javadecompilers.com/apk. Running the apk on an Android-Phone or emulator shows us the game: Tic Tac Toe. We also get a counter 0/1000000 on the bottom of the screen. Each win increases the counter by one. Naive approach by recompiling the app We used...

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UCSB iCTF 2017 - yacs

Yet another... cat service?!

yacs is a tool to store and later retrieve text snippets. If you store program source code there, it can even compile it for you! So handy. Of course, everything is protected using state-of-the-art user authorization and password hashing. It's a big C++ compiled binary which uses a local SQLite database file for data storage. Here's a normal create/list paste workflow: ___...

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EKOPARTY CTF 2016 - FBI 300

Bitcoin as OP_RETURN Dropbox

The description of the challenge was as follows: There has been some strange transactions on this blockchain! Let's do some research. After downloading and extracting the data (fbi300_64635d9aa64b20d0.7z) is was clear that we where looking at at a .bitcoin folder of a bitcoin-core client hat was started in regtest mode. As a first guess we used...

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TrendMicroCTF 2016 - SCADA 300

SCADA APT's FTW

The description of the challenge was as follows: In this challenge you are presented with a PCAP that comes from a network infected by a well known SCADA related APT Threat (hint: pay attention to potential C&C) Identify the relevant packets related to the malware and attempt to find the flag in the normal format So first we had to download and unpack the relevant file. After fiddling around with wireshark we identified a suspiciously looking HTTP...

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