1
Fund
Fresh wallet via a mixer
The airbag of DeFi · Chainlink CRE · NOWNodes
Catch attackers while they're still setting up.
Live on BNB Chain and Base mainnet. SENTINEL simulates every suspicious call and pauses your protocol before the strike.
- Probe block 126072959
- Pause tx
- Strike reverted
- 20.0 s probe→pause · 96/100 · 0 BNB lost
Every big hack has a rehearsal.
2
Deploy
The exploit contract
3
Test
A small probe
4
Strike
The real attack
Today the window between test and strike is wasted on a 3 AM alert and a multisig. SENTINEL uses it.
Eyes · Brain · Hand
Eyes · NOWNodes
- WebSockets newHeads + logs
- eth_getLogs scans
- debug_traceTransaction (callTracer) to catch re-entry
- debug_traceCall prestate diff to simulate the strike
- Wallet forensics from mixer events
- Chainlink price feeds read through NOWNodes RPC
- BNB Chain + Base
Brain · Chainlink CRE
- Deterministic rules → score. Re-entry +30, loss ≥20% +30, mixer gas +20, wallet <1h +16 = 96.
- Threshold 80.
- Hard guard: no pause without a hard signal and ≥5% simulated loss.
- Signs a report (vault, score, incidentId).
Hand · Guardian contract
- Accepts reports only from the forwarder, then calls pause().
- Cannot unpause, move funds, or upgrade.
- Onboarding = 2 transactions: grantRole(PAUSER_ROLE) + registerVault.
Proof on BNB Chain mainnet · 6 Oct 2026
20.0 s
probe → pause
96/100
CRE risk score
−89%
simulated loss if it landed
0 BNB
lost
Re-entrancy is the tip of the iceberg.
- Oracle / price manipulation
- Flash-loan attacks
- Governance takeovers
- Malicious upgrades
- Infinite mints
- Approval drains
- Access-control exploits
- Bridge drains
- Copycat attacks
- Cross-chain spread
They all test before they strike. Each becomes a new rule in the same CRE workflow. Any protocol with a pause switch plugs in.
Alert vs. doer
Monitoring tools
Alert a human. Minutes to hours.
Private bot
One server, one hot key.
SENTINEL
Simulates, acts in seconds, can only pause. Decision by Chainlink CRE.
You don't call the airbag during the crash. It fires on its own.
Built at TOKEN2049 Singapore Origins Hackathon by Team USquare · Ujjwal Bajaj, CEO, USquare Newtech Pvt Ltd.