Twenty-four hours awake in Seoul
Hanbok at Changdeokgung, Myeong-dong after the rain, and the reverse challenge that made the whole contest - CODEGATE 2025
2025
The 37% rule
Mathematics is not only for solving equations. It can also tell you when to stop looking, before you pass up the best option you will ever see. The 37% rule, applied to the decisions that matter.
7-Day Journey at GCC Taiwan
How you make friends with students from six countries, finish a project at 3 AM, and end up winning it - GCC 2025 Taiwan
2024
Three hours reversing, one strings command
Knowing when to stop is a skill. A teammate found the flag with one command while I was deep in the loader - UIUCTF 2024
When the compiler is the obfuscator
Nobody wrote an obfuscator for this one. Clang with optimizations on was enough to hide a single matrix multiply - Google CTF 2024
From logic capture to MSP430 firmware
A signal capture is just another file format. Decoding the UART, rebuilding the hex, and reversing what falls out - Midnight Sun CTF 2024
There is a knight inside this VM
Reversing a bytecode interpreter down to readable code, then solving the last step by hand instead of with a script - TetCTF 2024
2023
Hand-assembling bytecode for someone else's CPU
Once you know the instruction encoding, you can write programs for a machine that exists only inside one binary - CDDC 2023
Team notes from the hardest weekend of the year
A self-modifying compressor, a heap note, a hash length extension and a Torque script binary - DEF CON Quals 2023
Finding a decompiler for Elixir
What to do when the file format is one you have never seen before, and the challenge that took me longest - Angstrom CTF 2023
A flag checker with no JavaScript in it
The whole check is CSS layout. Opening one tag changes the page height, which slides an image into place - PlaidCTF 2023
2022
The driver rewrote its own code between every call
Eight IOCTLs, each patching the decrypt function before the next. Static analysis alone will not get you there - HITCON CTF 2022
A pizza order that overflowed into admin
Where Lua meets C, a missing parameter and a misused strncat are enough to order what the shop refuses - Hack.lu CTF 2022
Following a flag checker into kernel space
The binary carries its own driver as a resource, installs it, and sends your input there to be encrypted - WM CTF 2022
Four challenges, and a language made of colors
From debugging a DLL to reversing a program written in pixels, against a fifteen second timer - UIUCTF 2022
One line of anti-debug froze my browser
How DevTools detection makes a page impossible to debug, and why deleting a single line gives it all back - Google CTF 2022
Do not trust the disassembler to find everything
An ELF wearing an .exe extension, and a checker that only exists once you tell IDA that data is code - corCTF 2022
The wargame I learned reversing on: Reversing.kr
Full solutions in Vietnamese, from the first crackme up to a kernel driver. Good if you are starting out
2021
Where to start if you have never reversed anything
The whole beginner track in Vietnamese, with the tools you need and why each challenge is there - picoCTF 2022