CubeCTF 2026
- Starts
- Ends
- Runs for
- 8 hours
- Format
- Attack-Defense (online)
- Rating weight
- 24.71 - Strong field
- Teams registered
- 8
Run by CubeMastery, with prizes listed on CTFtime.
What the organisers say
CubeCTF is coming back this year with Attack/Defense! Game format will follow traditional FAUST-style A/D format, with infrastructure provided by glitchrange.com. Brush up on your vim shortcuts and tcpdump flags - the environment will be hosted in an isolated environment with only web console access and no direct internet connection to vulnboxes, so AI agents will not have access.
Prep briefing
What past editions were made of
Counted across 4 challenges from 2025, using the categories the scoreboards themselves used. Two things to hold in mind while reading it. The archive indexes challenges that someone published a solution to, not whole scoreboards, so this is the shape of what people wrote about rather than of everything that was set. And where a scoreboard gave no category the challenge lands in misc, so a large misc slice means “unlabelled” rather than “miscellaneous”.
4 challenges is a thin sample. Read the split below as a hint about this event rather than as its profile, and lean on the linked editions instead - they are the actual record.
- crypto 33%(1)
- forensics 33%(1)
- misc 33%(1)
What to have open when it starts
Crypto
Have the cipher identifier open on the first paste. Most of the round-one crypto is a classical cipher or an RSA parameter mistake, and both are recognised faster than they are solved.
- Cipher identifier and automatic decoder
- RSA decryption and attack runner
- XOR cipher decoder and key recovery
- Vigenere cipher solver with automatic key recovery
- Modular arithmetic and number theory toolkit
New to this? Read Classical ciphers and frequency analysis, XOR and the cost of reusing a key, Block ciphers, modes and oracles, RSA and the parameters that break it, Discrete logs, Diffie-Hellman and elliptic curves
Forensics
Start with the file's own claim about itself, then with what is appended after it ends. Both are one paste away.
- File type identifier by magic bytes
- Hex viewer and hexdump
- ZIP archive inspector
- PCAP analyzer for CTF network forensics
- Memory dump, disk image and registry hive analysis
New to this? Read File forensics and carving, Network forensics, Memory and disk forensics, Malware triage and defensive telemetry
Misc
Misc is whatever did not fit, which in practice means encodings and esolangs. Identify, do not guess.
- Cipher identifier and automatic decoder
- Recipe builder: chain decodes and transforms
- Brainfuck and esolang decoder
- Base64 decoder and encoder
- Regex tester with match offsets and capture groups
New to this? Read Recognising encodings, Misc, esolangs and prompt injection
The challenges people wrote about most
From previous editions, ordered by how many published solutions each attracted. Reading two solutions to one of these is the closest thing to a warm-up for this event that exists.
- Incantationcrypto · 2025 · 1 writeup
- Nation State Hackingmisc · 2025 · 1 writeup
- Workerdbunknown · 2025 · 1 writeup
- Writeup01forensics · 2025 · 1 writeup