# A public $51.2K backdoor-recovery challenge > Source: > Published: 2026-07-15 16:10:50+00:00 We put together a hands-on demonstration of a model-supply-chain backdoor and would genuinely like this community to try to break it — and to tell us what a scanner *should* be catching here. **What’s open:** `Vulcora/protora-mbd-challenge-0` … `-6` , all grown from`HuggingFaceTB/SmolLM2-135M-Instruct` , ~861 MB each, statistically indistinguishable.**The task:** recover the exact trigger sentence for the hidden model. It’s self-verifying — the sentence *fires*, so no trust in us is required. Full rules: [The $51,200 Model-Backdoor Challenge — the day you start looking](https://protora.vulcora.se/challenge) **What we found benchmarking it (and why we think it’s interesting):** we ran a shelf of published backdoor scanners against this construction. The image-classifier tools don’t apply to a causal LM; of the ones that run on an LLM, all miss it, and a couple rank a clean model as *more* suspicious than the backdoored one. Our read: the field’s detectors assume a learned statistical signature, and this construction doesn’t have one. Detection of *presence* is one problem; *recovery* of the trigger is a much harder one, and that’s the part we can’t do either — yet. **What we’d love from you:** Not selling anything in this thread — the models are open, the answer publishes against a pre-registered commitment, and we want the field to take an honest shot at it.