Skill: Cross-Chain Timing Analysis

Type: Thought-template (instantiate before use) Research basis: Multi-block arbitrage windows, bridge latency exploitation

Trigger Patterns

bridge|L1|L2|tunnel|messenger|crossChain|sendMessage|receiveMessage|
_processMessageFrom|LayerZero|CCIP|Wormhole|Arbitrum|Optimism

Reasoning Template

Step 1: Identify Sync Mechanism

• Find all cross-chain messaging calls in {CONTRACTS}
• For each call, determine:
  • What state is being synced? (rates, balances, epochs, totals)
  • What triggers the sync? (every operation, periodic, manual)
  • What bridge/messenger is used?

Step 2: Measure Timing Window

• Research {BRIDGE_PROTOCOL} documentation for realistic latency
• Typical ranges: optimistic rollups (10-30 min), zk-rollups (minutes), standard bridges (20-60 min)
• Document: submission -> finality -> execution timeline

Step 3: Trace Stale State Usage

• From {SYNC_POINT}, identify all state that depends on synced values
• For each dependent operation at {DEPENDENT_FUNCTIONS}:
  • Is fresh state required or is stale acceptable?
  • What decisions are made with potentially stale data?

Step 4: Model Arbitrage Sequence

1. Attacker monitors {SOURCE_CHAIN} for state changes at {MONITOR_POINT}
2. State change triggers sync message (latency window opens)
3. Attacker executes on {DEST_CHAIN} at {EXPLOIT_FUNCTION} using stale {STALE_STATE}
4. Sync message arrives, state updates
5. Attacker profits: {PROFIT_CALCULATION}

Step 5: Quantify Viability

• Maximum {STALE_STATE} delta during sync window: {MAX_DELTA}
• Profit calculation: {PROFIT_FORMULA}
• Cost calculation: gas + bridge fees + capital lockup
• Viable if: profit > cost AND repeatable

Key Questions (must answer all)

1. What is the realistic sync latency for {BRIDGE_PROTOCOL}? (cite documentation)
2. Can an attacker monitor {SOURCE_CHAIN} and front-run sync on {DEST_CHAIN}?
3. What is the maximum {STALE_STATE} change during normal operation?
4. Is this attack repeatable or one-time?

Common False Positives

• Monotonic state: If {STALE_STATE} only increases (never decreases), arbitrage may not be profitable in both directions -- verify directionality
• Negligible delta: If max delta during sync window is <0.1%, may not be economically viable after costs
• Rate limiting: If operations have cooldowns longer than sync latency, window may not be exploitable
• Same-block dependency: If dependent operation requires same-block freshness (checked via block number), stale state is rejected

Instantiation Parameters

{CONTRACTS}           -- List of contracts to analyze
{BRIDGE_PROTOCOL}     -- Specific bridge (LayerZero, CCIP, Arbitrum Messenger, etc.)
{SYNC_POINT}          -- Function/event where sync occurs
{DEPENDENT_FUNCTIONS} -- Functions that read synced state
{SOURCE_CHAIN}        -- Chain where state originates
{DEST_CHAIN}          -- Chain where stale state is exploited
{MONITOR_POINT}       -- What attacker monitors on source chain
{EXPLOIT_FUNCTION}    -- Function attacker calls on dest chain
{STALE_STATE}         -- Specific state variable that becomes stale
{PROFIT_CALCULATION}  -- Formula for attacker profit
{MAX_DELTA}           -- Maximum observed state change
{PROFIT_FORMULA}      -- (new_value - old_value) * position_size

Output Schema