The writeup archive

The two apps are two halves of one decryption scheme. Each ships a 32 KB half.bin. At runtime the native libs exchange halves through sealed memfds, XOR them, and ChaCha20-decrypt the…

A 3-drive RAID5 NAS lost power while isfc-stage.py was rewriting a sealed report. Nobody saved the md settings, and the sealing key was burn-after-read. Recovery needed four steps:

It is tiny (~10 KB), static, stripped, and uses raw syscalls (no libc). Running it:

the-press** (binary: chall_1_) is a stripped x86-64 ELF. It reads exactly 32 bytes from stdin, compresses them with a custom LZMA-style range encoder, and compares the 36-byte result…

A regression service claims a deletion request was fulfilled by exact retraining. We get:

A federated linear regression model (16 features plus a bias term, every label equal to 1) was updated over many rounds. Each round mixed three clients with integer mix weights, and only…

Connecting to the service prints a banner and a prompt:

base.odex is not a real ART/OAT file — it's a hand-crafted container with a small AArch64 "native code" section and three methods:

We are given a stripped 64-bit ELF binary chall. Running it:

observations.json holds 6000 pairs (multiplier mᵢ, observation oᵢ) with

The challenge provides model (1).py and observations (1).json. The forty silhouettes are modular subset sums of fourteen hidden atoms. Recovering the binary subset mask reveals the…

Running the binary with ? prints the archive catalogue. The live prompt also prints all the surviving job cards:

loom is a stripped x86-64 ELF that reads exactly 32 bytes from stdin, runs them through roughly a million generations of a second-order (reversible) cellular automaton, and compares the…

chall is a stripped 64-bit ELF that reads exactly 16 bytes of input and prints CORRECT iff the input satisfies a very specific arithmetic condition. At a high level the check is a…

The challenge provides chall.py and output.json. The service uses a polynomial ring

Given: a single 64 MiB NTFS raw image, evidence.img.

The challenge provides two RSA moduli, N1 and N2, a public exponent e = 65537, and a ciphertext ct. The flag is textbook RSA-encrypted under N1.

The challenge chooses ten secret weights a_1, ..., a_10 modulo a 200-bit prime M, then publishes 50 totals:

The solution combines commit-journal recovery, TCP and Modbus fragment reconstruction, ECDSA nonce reuse, DTMF decoding, and an authenticated OTA decryption. All work is local; no…

We are given chall.py and output.json. A permutation P acts on GF(p)^2 with p = 4611686018427387761 (a 62-bit prime, p % 3 == 2) over R = 20 rounds:

Field teams use the Field Console handset app to talk to dispatch nodes on a depot network. Routine (operator) jobs work fine; the maintenance path is meant to be off-limits. We are…

The worker read 24 payloads of 24 bytes each. Concatenating them in ascending slot order gives 576 bytes with SHA-256:

The front desk serves a small OCI-inspired registry. Each POST /session creates a private, writable copy of repository cryovault with:

The application loads its document data from: