Every challenge I've solved and documented. Search by name, filter by discipline or event — no login, no gatekeeping.
146 writeups
The moonchace hardware challenge exposes a tiny VM ("LUN4R-MU") over TCP (103.49.131.90:31337) whose debugger accepts load $rN , load $rN 0($r0), batch … end, reset, and quit commands,…
The H7CTF 2026 crypto target in this folder is a firmware-signing service built as an LMS-style hash signature scheme: WOTS one-time leaves wrapped in a Merkle tree (TREE_H = 4, 16…
An LCG with unknown a, c and known modulus m = 2³² leaks consecutive outputs, then uses the same generator as a keystream to XOR the flag. Recover a and c from three outputs, then…
pwn/4 of H7CTF 2026 hands you the ledger binary, its exact glibc 2.39 runtime, and matches everything with a classic tcache-overwrite chain on a four-action heap menu.
Luna CTF hosted an EVM playground ("KumoSec ChainVault") behind a team-token API at http://103.49.131.90 with a JSON-RPC node at /chain/rpc. Two contracts exist: an AuditorRegistry…
This H7CTF 2026 reverse challenge hands you a static, stripped Linux binary (vmrun, a "shard runtime") and eight-ish .shard files ("guardian agents") whose names are SHA-looking content…
A pwn challenge around kairothd, an "adaptive instruction classification engine": it learns how your program behaves, decides it is trustworthy, and stops double-checking. The binary…
For H7CTF 2026 this web-style challenge is a WebAuthn/FIDO2 Relying Party ("H7 Passport") with a twist: it accepts three attestation formats (packed, tpm, android-key), but only…
The "ground" web challenge (SunshineCTF 2026) is the Punxsutawney Orbital Weather Authority's Perpetual Forecast Console. A leftover operator comment in the page source hands out a…
The GenCyS CTF 2026 challenge folded into this folder is a story-driven intelligence exercise around TheSecureTrust Bank: a mission-kickoff email carrying a nested alert.eml attachment,…
A network-forensics challenge whose answer is hidden in plain sight as a Base85 string in the incident artefacts. Decode it and the flag falls out.
For H7CTF 2026's pwn/1 challenge, the target is gatecache (shipped inside keepalive.zip): a stripped PIE x86-64 C++ service, built on Ubuntu 22.04 / glibc 2.35, that listens on TCP 9006…
H7CTF 2026's misc/2 is a hardware-verification challenge with a crypto-challenge smell. The FoundryProof sign-off certifies a combinational 32-bit netlist as equivalent to a golden…
The challenge handed over hereyougo.png, a PNG whose IHDR height field had been shrunk so most of the image was invisible in a normal viewer. Because JPEG-style truncation does not apply…
A custom "elliptic curve" cryptosystem with a = 0, b = 0 — the curve is
The same plaintext encrypted twice under one RSA modulus with two different public exponents, e₁ = 65537 and e₂ = 65539. Since gcd(e₁, e₂) = 1, Bézout coefficients give the plaintext by…
In H7CTF 2026's crypto track, a homomorphic-encryption analytics service leaks enough noise for full key recovery. The service is a minimal CKKS-style scheme over Z_q[x]/(x^N+1) with N =…
"Bring Your Own Code" — BYOC's chall.c does exactly what its name promises: it mmaps 200 bytes as RWX, reads up to 200 attacker-controlled bytes into it, and calls it. No bug to find at…
Håstad's broadcast attack with a twist: the same message is RSA-encrypted under three moduli with e = 3, but the plaintext is first mapped through a known linear padding m' = a·m + b.…
A small-private-exponent RSA challenge placed just beyond Wiener's bound, so continued fractions alone fail. The private exponent is small enough for the Boneh-Durfee lattice attack…
Two RSA-CRT signatures over the same message, with a hardware glitch flipping a single bit in one signature's computation modulo q. That's the textbook setup for the Bellcore fault…
A core-network forensics challenge: an IXP border router's BGP session is captured, and the exfiltrated flag is smuggled inside BGP COMMUNITY attributes of eight UPDATE messages. Each…
The captured_tokens.json artifact contains ECDSA session-attestation signatures intercepted from "auth-gw" (VLAN 12) on secp256k1 with SHA-256. A leaked commit note in gen_notes.txt…
For H7CTF 2026 this hardware-adjacent challenge hands you a DOS ROM for a "recovered status panel" that boots under qemu-system-i386 (-drive format=raw,file=panel.rom). In stock…
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