Nexsiz
Stateful Network Protocol Fuzzer — pure Rust, semantic mutation, integrity repair, hybrid grey-box coverage, and post-discovery existence scripts.
What is Nexsiz?
Nexsiz is a high-performance, modular network protocol fuzzer designed to explore the deepest regions of a protocol’s state machine — areas where conventional fuzzers lose structural validity or state context and remain blind.
Design priorities are explicit: precision over volume, structural integrity after mutation, hybrid black/grey-box feedback, and operational resilience under realistic network conditions.
Offensive tooling must execute correctly, remain maintainable under operational pressure, and preserve the operator’s ability to reason about the exact behaviour the target exhibited.
Core Capabilities
Semantic Mutation
Hierarchical field / message / sequence mutators that respect protocol grammar.
Integrity Repair
Automatic restoration of length fields, checksums, framing, and terminators post-mutation.
Grey-box Coverage
CoverageProvider trait, AFL-style 64 KiB edge map, Frida agent integration.
Snapshot & Desocket
ProcessRestart / CRIU backends and protocol-level connection reset without full reconnect.
NXS Existence Scripts
Post-event actors for repro, differential probe, auth escalation, chain analysis, and more.
Minimal Surface
Default build depends only on libc. LibAFL, JSON models, and CRIU are optional features.
Documentation Status
This site is the official operator documentation for Nexsiz. Guide, reference, architecture, features, NXS, advanced, and security sections are populated from source.