Attack Vector
Grace period after sequencer restart creates unfair liquidation window. Liquidators front-run with stale oracle prices before borrowers can react.
Kill Chain
1L2 sequencer goes down.
2Prices move adversely during downtime.
3Sequencer restarts.
4Liquidators front-run during 3600s grace period before oracle updates.
Impact HIGH
Mass liquidations at stale prices. Borrowers cannot protect during downtime. Liquidators extract collateral at discount. Severity HIGH — systemic during outage events.
Severity
HIGH — systemic during sequencer outage events on Arbitrum/Optimism.
Proof of Concept
1Monitor Arbitrum sequencer uptime feed.
2On downtime detected: prepare liquidation txs.
3On restart: submit during 3600s grace period before oracle updates.
Caveat
Exact financial impact depends on market conditions during specific outage — cannot pre-compute.
Detection Signals
▸Track sequencer uptime oracle 0x4da69F028a5790fA447...
▸Alert on downtime >5 min.
▸Monitor Aave liquidation spike within 60s of restart. Cross-reference oracle staleness.
Findings
NP-SUB005-001 HIGH 3600s grace period too long.
NP-SUB005-002 STRONG Liquidation bots demonstrably front-run sequencer restarts historically.
NP-SUB005-003 OPEN Grace period is governance parameter — not immutable.
Sorry
Exact financial impact depends on market conditions during specific outage — cannot pre-compute.