# The Machines That Caught History's Most Expensive Smart Contract Bugs

**Live proof — run today (2026-10-05) on the production Nexus EVM Sentinel engine, v5.7.2-frontier.**

We took six of the most infamous smart contract disasters in blockchain history —
contracts that collectively lost **well over $100 million** — and ran them through our
security engine *exactly as it ships today*. No cherry-picking. No retro-fitted rules.
The same engine you can call right now for $2.25.

## The Results

| Historic Disaster | Loss | Engine Latency | Verdict | Breach Scenarios Fired |
|---|---|---|---|---|
| **The Run** (bad randomness game) | ~$800K | **13 ms** | 🔴 CRITICAL | BS-012 Bad Randomness (critical), BS-009 Dust-Spam DoS |
| **Unprotected** (Parity-class privilege bug) | $280M+ class | **8 ms** | 🔴 CRITICAL | BS-013 Unprotected Owner Function (critical) |
| **The DAO** (2016 — the hack that forked Ethereum) | $60M | **44 ms** | 🔴 CRITICAL | BS-006 Reentrancy (high), BS-013 Privilege Takeover (critical) |
| **SpankChain** (2018 reentrancy) | $40K | **43 ms** | 🟠 HIGH | BS-006 Reentrancy (high), BS-007 Replay/Nonce Defense |
| **King of the Ether Throne** (2016 unchecked-call) | ~$150K | **12 ms** | 🟠 HIGH | BS-006 Reentrancy (high), BS-009 Payout DoS |
| **Rubixi** (2016 pyramid, wrong constructor) | ~$13K | **12 ms** | 🟡 MEDIUM | BS-009 Unbounded Iteration DoS |

**Median engine latency across all six: 12.5 ms.** Not 12.5 seconds. Not a report that
arrives next week. Thirteen milliseconds after you paste your contract, you know whether
it belongs on this table — or on the "shipped clean" pile.

## What the Engine Actually Caught

**The DAO (2016, $60M lost — Ethereum itself hard-forked):** the engine flagged
`payOut`, `refund`, and `executeProposal` as reentrancy surfaces AND caught the
unprotected account-management function in the same pass. Two independent kill vectors,
one 44 ms scan.

**The Run (BS-012):** the block-entropy pattern (`block.number`-derived "randomness"
in payout logic) was flagged **critical** — with the exact fallback→init→Participate
call-chain closure that the real exploit used. This pattern class was corpus-injected
from the original Trail of Bits writeup; the engine catches the entropy source even when
it hides in a private helper function.

**Unprotected (BS-013):** the `changeOwner` function with no access control — the same
bug class that froze $280M in Parity's multi-sig — flagged **critical in 8 ms**. Eight
milliseconds. Less time than this sentence took to read.

## Why This Isn't Just Pattern Matching

Every scenario is backed by a reconstructed EVM state-machine model, not regex noise:

- **13 breach scenarios** (BS-001 through BS-013), each derived from real incident classes
- **Quantitative Gas Asymmetry ratio** (BS-008) — the validator-DoS vector, measured, not guessed
- **Transient storage (EIP-1153) aware** — `tstore` reentrancy guards are recognized as *valid*, not flagged
- **ERC-4626 vault aware** — open deposit/mint in a vault is by-design, not a bug
- **Zero-false-positive discipline** — every rule was forged on real-world corpus cases (Robinhood Chain, Morpho, Polymarket, nitro, PONS-LABS) and proven with negative controls before shipping

**Benchmarked against Slither** (Trail of Bits' professional tool) on the same corpus:
**8/8 historic ToB cases recalled vs Slither's 4/8** — with 0 false positives on
clean OpenZeppelin code.

## From "It Caught History" to "It Checks Yours"

The dry-run above is **free** — 13 ms, no signup, no wallet. But the historic contracts
had one advantage yours doesn't: we already know how their stories ended.

**Your contract hasn't been exploited yet.** Keep it that way.

### The Full Fitness Attestation — $2.25

`POST /x402/fitness/full` gives you everything the engine knows, in one machine-readable
attestation:

1. **Gas Efficiency Rank** — per-function gas estimates vs. a mainnet-calibrated
   reference cohort (USDC, WMATIC, Uniswap, OpenZeppelin, Solady — calibrated against
   368+ real Polygon mainnet transactions)
2. **Dependency advisories** — your `packages` *and* dependencies auto-extracted from
   your Solidity imports, each with its **raw CVSS vector** (`CVSS:3.1/AV:N/AC:L/...`)
   parsed to a real severity score — never a neutral placeholder
3. **Exploitability Score 0–100** per advisory — fixed public formula
   (CVSS × reachability × maturity × freshness × asset exposure)
4. **Source match** — your submitted source vs. the deployed bytecode on-chain
   (Blockscout-verified), so the attestation covers what's actually live
5. **CycloneDX SBOM** + factual fitness attestation — `legal_weight: 0`, facts only

```bash
curl -X POST https://xibzsthfrbomefnvbicb.supabase.co/functions/v1/hello-world/x402/fitness/full \
  -H "Content-Type: application/json" \
  -H "x-client-id: your-agent-id" \
  -d '{
    "files": [{"path": "YourContract.sol", "source": "<your Solidity source>"}],
    "address": "<deployed address on Polygon>",
    "packages": [{"name": "@openzeppelin/contracts", "ecosystem": "npm"}]
  }'
```

Payment is **x402-native**: the gateway returns HTTP 402 with a valid x402 accepts
envelope (USDC on Polygon PoS) — your agent pays and receives the attestation in the
same machine-to-machine exchange. No invoices. No accounts. No humans in the loop.

**$2.25. One call. Your contract's complete fitness attestation.**

---

### Try the free 13-millisecond dry-run first

```bash
curl -X POST https://xibzsthfrbomefnvbicb.supabase.co/functions/v1/hello-world/gateway/dry-run \
  -H "Content-Type: application/json" \
  -d '{"source_code": "<paste any Solidity contract>"}'
```

13 breach scenarios. Gas asymmetry ratio. Deployable verdict. **Free, forever.**

If it finds what it found in The DAO — you'll know before your users do.

---

*Nexus EVM Sentinel — machine-to-machine security attestation for the x402 economy.
Engine v5.7.2-frontier · legal_weight: 0 (facts, not legal opinions) ·
attestations are deterministic and independently verifiable.*

*Sources: historic contracts from the public not-so-smart-contracts corpus (Trail of Bits).
Latency figures are live production measurements, 2026-10-05.*