fix(data-fetcher): authenticate bridge event emitter before indexing transfers#613
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fix(data-fetcher): authenticate bridge event emitter before indexing transfers#613vladb-ai wants to merge 2 commits into
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…transfers The bridge transfer handlers selected work purely by event topic and returned matches() === true unconditionally, so any L2 contract could emit ABI-shaped DepositFinalizedAssetRouter / WithdrawalInitiatedAssetRouter or legacy FinalizeDeposit / WithdrawalInitiated logs and have them indexed as real bridge deposits/withdrawals with attacker-chosen from/to/amount/token. Asset Router handlers: require the log emitter to be the L2 Asset Router system contract (L2_ASSET_ROUTER_ADDRESS, 0x..010003), which is deployed at the same fixed address on Era and every ZK chain (verified on Era mainnet and ZKsync OS mainnet). Legacy shared-bridge handlers: legacy events have no single authoritative emitter (canonical shared bridge plus deployment-specific custom token bridges, e.g. Lido wstETH), so authenticate against a trusted set built from zks_getBridgeContracts (cached) plus a configurable allowlist via the new TRUSTED_LEGACY_BRIDGE_ADDRESSES env var. Chains without zks_getBridgeContracts (e.g. ZKsync OS) fall back to the allowlist; they emit no legacy events. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
…ache RPC fallback Follow-up to the bridge emitter authentication fix, addressing review findings: 1. Observability for the legacy allowlist trade-off: with an empty allowlist the legacy handlers silently drop real custom-bridge transfers (e.g. Lido wstETH). Add a skipped_untrusted_legacy_bridge_logs_total metric and a debug log naming the skipped emitter so operators can discover bridges to allowlist instead of losing the data silently. Logic moved into BlockchainService.isTrustedLegacyBridgeEmitter. 2. Document the TRUSTED_LEGACY_BRIDGE_ADDRESSES env var in .env.example and the data-fetcher README, including the Era mainnet Lido wstETH example. 3. Cache the trusted-set fallback on deterministic zks_getBridgeContracts failures (e.g. -32601 method not found) so a failing call is not re-issued for every legacy log; only transient network errors remain uncached and are retried. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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Problem
The bridge transfer handlers in
data-fetcherselect work purely by event topic and theirmatches()returnedtrueunconditionally, never checking the log emitter. As a result any unprivileged L2 contract can emit ABI-shaped bridge logs and have them indexed as real bridge deposits/withdrawals with attacker-chosenfrom/to/amount/token:DepositFinalizedAssetRouter/WithdrawalInitiatedAssetRouter(Asset Router path)FinalizeDeposit/WithdrawalInitiated(legacy shared-bridge path)These fabricated transfers surface in the explorer UI and the public API (e.g. on a victim address's
/transfers), i.e. misrepresentation of transaction data. No fund safety impact; data-integrity only.Fix
Asset Router handlers — require the emitter to be the L2 Asset Router system contract (
L2_ASSET_ROUTER_ADDRESS,0x…010003). This is deployed at the same fixed address on Era and every ZK chain, so the check is chain-agnostic with no config.Legacy shared-bridge handlers — legacy events have no single authoritative emitter (the canonical shared bridge plus deployment-specific custom token bridges, e.g. Lido wstETH). They are authenticated against a trusted set built from:
zks_getBridgeContracts(canonical bridges; cached), andTRUSTED_LEGACY_BRIDGE_ADDRESSESenv var (comma-separated).Chains that don't implement
zks_getBridgeContracts(e.g. ZKsync OS) fall back to the allowlist; they emit no legacy events.Verification
data-fetchersuite green (400 tests; new accept/reject cases for both handler families +getTrustedLegacyBridgeAddresses). Lint clean.0x…010003; the patched handler accepts those and rejects other emitters.TRUSTED_LEGACY_BRIDGE_ADDRESSESre-includes it, and an attacker emitter is rejected.Operator note
To keep indexing legitimate custom legacy bridges, set
TRUSTED_LEGACY_BRIDGE_ADDRESSES. For Era mainnet this includes at least the Lido wstETH bridge0xe1d6a50e7101c8f8db77352897ee3f1ac53f782b. Recommend scanning historical legacy-topic emitters per network to seed this list before rollout so no legitimate custom-bridge transfers are dropped.🤖 Generated with Claude Code