feat(web3): extend AST-W02 with hardcoded fee-recipient detector#8
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Detects address literals that sit inside a fee/affiliate context within Permit2 typed-data assembly and aren't declared in web3.policy.allowedContracts. Closes the 0x SKILL fee-skim pattern (hardcoded SWAP_FEE_RECIPIENT + SWAP_FEE_BPS baked into the signed EIP-712 message) that the existing W02 sub-rules don't catch. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
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Summary
SWAP_FEE_RECIPIENT+SWAP_FEE_BPSbaked into signed EIP-712 messages).manifest.web3.policy.allowedContractsAND appears within ~3 lines of a fee token (fee,feeBps,feeRecipient,swapFeeRecipient,swapFeeBps,affiliate,referrer,partner,takerFee,protocolFee,treasury).0xdeadburn sink, the canonical Permit2 verifyingContract, allowlisted contracts, comments, and lines withfeeBps = 0disclaimers.web3-feeskim-vuln-skill/and 9 new unit tests.Test plan
bun test --filter @agentsec/web3— 253 pass, 0 failbun run build && bun run test— full monorepo, all greenbun packages/cli/src/cli.ts audit --path e2e/fixtures/web3-feeskim-vuln-skill --verbose— fires AST-W02 critical "Hardcoded fee recipient in Permit2/swap typed-data"bun packages/cli/src/cli.ts audit --path e2e/fixtures/good-web3-skill --verbose— no new findings (regression clean)bun packages/cli/src/cli.ts audit --path e2e/fixtures/w02-permit2-vuln-skill --verbose— existing W02-001/002/003/010 still flag🤖 Generated with Claude Code