LabyREnth 2017 Write-up: "EzDroid"

Thu, 27 Jul 2017 20:49:00 +0000

Mobile track #1 - EzDroid Provided is an Android app package EzDroid.apk. I typically use an Android emulator for testing, it’s free and easy to install on all major platforms, so it’s pretty much a no brainer. After installation, it looks like it maanges to start but exits shortly after, for some unknown reason. Looks like it is time to inspect the code. I like looking at high-level languages, so let’s start with that first.

PlaidCTF 2015 "RE GEX" Write-up

Mon, 20 Apr 2015 22:34:00 +0000

This challenge came with a simple Python TCP server and a monstrous regex in a separate file. It consists of multiple sub-patterns (2563 to be exact), separated by OR operators1. To get the flag, the input supplied must NOT match any of these sub-patterns. If you break up the large regex expression, you see something like this: ^(.*[^plaidctf].*| .{,170}| .{172,}| .{88}[padt].{60}[licf].{6}[plai].{14}| .{60}[aitf].{17}[pldc].{85}[dctf].{6}| ... .{54}[pldc].{88}[plai][aitf].{26}| .{11}[aitf].{41}[aitf].{97}[padt].{19})$ The 3 conditions listed up front give you a hint to the requirements: must be made up of the letters plaidctf and be of length 171.

Z3 on irq5 test

LabyREnth 2017 Write-up: "EzDroid"

PlaidCTF 2015 "RE GEX" Write-up