Paweł Łukasik - All things reversed

The Gambler - Midnight Sun CTF 2022

The secret is 'Knowin' what the cards were'.Apart from the message we are give the file, with the instruction to run it with mono the_gambler.exe. This alone gives away the fact that, this is a .NET assembly and we can skip any initial analysis and go straight

1337up

Tinybit - 1337up CTF

Just try a little bit harder! Brb, shouting intigriti.rocks!🔗 Download link: mw.linux 🔗 Download link: mw.darwin 🔗 Download link: mw.windows 🚩 No flag format. The flag starts with z and ends with ! ✍️ Created by HazcodNote: The shouting part was only added in the middle of the CTF. Three binaries,

1337up

Bitcoins for Flags

BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP BIP🔗 Download link: BitcoinsForFlags.zip 🚩 Flag format: CTF{} ✍️ Created by Ferib HellscreamFile

insomnihack

Insomni'Hack - Corona Virus

A devastating computer virus infected millions of machines around the world. Security experts were able to capture a sample, but the virus seems to be looking for something specific, and acts frustrated if it is not happy. Who knows the horrors it may unleach onto the world if...or when

ctf

babyRust - N1CTF

This fun, little challenge was RE challenge during N1CTF. We are given the following Rust source code: macro_rules! check { (@s n1ctf{$Never:tt}) => { check!(stringify!($Never)) }; (@e ($Never:expr,$Gonna:expr,$Give:expr); (Never gonna give you up $($code:tt)*)) => { $Give += true as usize; check!(@e ($Never,

flare-on 8

Flare-On 8 - Antioch

To solve this challenge, you’ll need to …AAARGHThis challenge was really AAARGH for me. In retrospect I wonder why I didn't see what I was supposed to see and due to that lost almost a week on this fairly easy challenge. But let's start from the beginning. We are

flare-on 8

Flare-On 8 - Flare VM

Because of your superior performance throughout the FLARE-ON 8 Challenge, the FLARE team has invited you to their office to hand you a special prize! Ooh – a special prize from FLARE ? What could it be? You are led by a strong bald man with a strange sense of humor into

flare-on 8

Flare-On 8 - known

We need your help with a ransomware infection that tied up some of our critical files. Good luck.With the second challenge, it's a bit step up in the difficulty. We are given an EXE with some files (different types; images images and text) that has been encrypted. Opening file

flare-on 8

Flare-On 8 - credchecker

The first task in this year competition. It is a single HTML file. Inside we can find a simple check for credentials. function checkCreds() { if (username.value == "Admin" && atob(password.value) == "goldenticket") { var key = atob(encoded_key); var flag = ""; for (let i

flare-on

Flare-On 8 - Beelogin

In this challenge we are given a huge, 3.10 MB html file. Opening it, we can see there's a HTML form, and a lot of JavaScript. A lot. It's obfuscated too. Looking closer, it appears that it contains mostly the garbage and only some parts are relevant. One valid

flare-on

Flare-On 8 - Pet the Kitty

Hello, Recently we experienced an attack against our super secure MEOW-5000 network. Forensic analysis discovered evidence of the files PurrMachine.exe and PetTheKitty.jpg; however, these files were ultimately unrecoverable. We suspect PurrMachine.exe to be a downloader and do not know what role PetTheKitty.jpg plays (likely a second-stage

decompilation

Don't trust the decompilers

Decompilers can be your greatest ally or your greatest enemy. Basing the analysis only by the result of only one tool can fail you greatly. See for yourself. Prefer to watch? Check out this video. Recently, I was solving one of the challenge from ångstromCTF 2021 and after opening the

midnightsun

Solving Geanu

Geanu was a simple RE challenge from MidnightsunCTF. The task starts by print the following ASCII-art of Keanu and awaits our input. Keanu from Geanu ;)After getting user input it finishes. Let's fire up Ghidra and load the binary. Since the binary is written in Go, we can apply 'golang_

r2

Debugging r2 - child processes

If you ever want to debug r2 while it is debugging another process (so basically debug while debug r2 -d /bin/ls or when using ood) remember about few important things. Radare2 will create a new process so it is important to be sure if gdb is set to attach

r2

Debugging r2

This will be a short one. If you ever need to debug Radare2, and after running it under dbg you can't get into the debugger after hitting ^C as it should, remember that r2 handles this shortcut and this won't work. Instead use this: kill -SIGTRAP $(pidof r2) This cause

ghidra

Automating Ghidra - part 3

In the third installment of this series (if you haven't read/seen here's - part 1 & part 2) we will be reconstructing program flow. This is useful for tasks such as Towel's armageddon. Note: If you prefer watching, have a look at my YouTube channel. The difficulty of this

net user /times

You probably know this but in case you don't, Windows has built in feature for setting up allowed login days and hours for a particular account. It can be done in the following way net user account_name /times:[{times | ALL}] but when I used it to restrict my kids

challenge

Rusty

So I had my debut as an author of a task for a public CTF event. I've created a challenge called Rusty, and let's say it collected some mixed reactions. I've labeled it as an easy RE challenge, but only ten teams managed to solve it in the end -

ghidra

Automating ghidra

Ghidra is an awesome RE tool that quickly took off after its initial launch in 2019. It can display not only the disassembly of our binary but also have a decompiler that allows us to see a bit higher level code. You can also extend it by using python or

nes

Solving Space Fights CTF

Few months back I was solving a CTF challenge for the NES system. It was one of the Flare-On challenges for 2019. This time we will solve another one for the same system. A challenge named Space Fights CTF could be found on github along with the source code but

tamctf

TAMUCtf - leaning tower

There were multiple things wrong with this CTF but this one challenge was an interesting one. Windows binary, no noticeable entry point and no messages on screen. It's time to use our tools to dissect this one. Prefer watching? As usually, if possible, starting this task from running the binary

debugging

Debugging .Net applications without source code with dotPeek Symbol Server

Few years ago I've made a video that demonstrates how one can debug (from Visual Studio) without having source code by using the dotPeek Symbol Server. You can see the video below: DotPeek is one of many competed .NET decompiler (I ❤ dnSpy) but it has a great feature that allows

insomnihack

Kaboom!

This wasn't a difficult task but it had one tricky trick that made it took way more time than it should be required. We started with an exe file that when loaded in any disassembler tool (e.g. Ghidra) or do some preliminary checking to see that the file was

hitcon

Core Dumb - HitCon 2019

Note: challenge was solved together with Disconnected. Damn it my flag checker is so buggy it destroyed the program itself 😱 All I left is a core dump file :( Could you help me recover the flag ? Q_QLet's start by checking the file that we are given in this challenge: λ

lego

Hitcon 2019 Qualification - EV3 Arm

It's one of those challenges that brings together two things that I like - this time it was reverse engineering nad lego bricks. What was the input in this challenge was a picture that, supposedly depict how the robot was programmed and a rbf file that contains the aforementioned robot