OAK — OnChain Attack Knowledge

Worked example · 2026-10

Autheo THEO — the warp-route token accepted any message its single trusted relayer delivered, and 19M THEO arrived with nothing locked on the origin — Autheo / Base (Hyperlane warp route) — 2026-10-12

Loss
~700.8 ETH (~$1.76M) extracted by selling unbacked THEO for WETH, USDC and cbBTC and bridging to Ethereum (PeckShield; Defimon ~$1.7M). THEO fell ~92%.
OAK Techniques observed
OAK-T7.003 (Cross-Chain Bridge Laundering — the ETH proceeds were bridged from Base to Ethereum per PeckShield; see techniques/T7.003-cross-chain-bridge-laundering.md). OAK-T10.002 (Message-Verification Bypass — primary. Per Defimon, THEO is a Hyperlane HypERC20 whose security module is a TrustedRelayerIsm: one relayer key authorises any inbound message. A message from origin domain 2127 minted 19,000,000 THEO from the zero address with no lock or burn on the origin; 9.5M were then run through a 54-swap extraction across the THEO/USDC pair and Uniswap v4 / Hydrex pools. See techniques/T10.002-message-verification-bypass.md). Whether the attacker held the trusted relayer key or the module trusted an address the attacker controlled is not disclosed.
Attribution
pseudonymous (0x3048b4ee5a070f33b73e3401829847255079e0ad).
Key teaching point
A single trusted relayer is a single key with mint rights. The warp route's verification was as strong as one relayer's key management, which is not message verification.

Summary

Defimon dated the mint to 2026-10-12 and PeckShield reported the cash-out on 2026-10-13. Autheo told users not to buy, sell or bridge THEO while it investigated.

Timeline (UTC)

Read it as three stages. Flaw: one relayer key can authorise any message. Take: a 19M unbacked mint, then a 54-swap dump. After: ETH bridged to Ethereum; the operator has not published a root cause. Times are from the Defimon and PeckShield posts.

When What happened OAK
Before 2026-10-12 (since when: undisclosed) THEO on Base is a Hyperlane HypERC20 warp-route token whose security module is a TrustedRelayerIsm: a single relayer key can authorise any inbound interchain message (Defimon). T10.002
Before the mint (undisclosed) Whether the attacker held the trusted relayer key, or the module trusted an address the attacker controls, is not disclosed. Preparation and funding are not published. —
2026-10-12 In an earlier transaction (0x4fdbbc5e…, full hash not published) the attacker delivers a Hyperlane message from origin domain 2127. handle() mints 19,000,000 THEO from the zero address with no lock or burn on the origin chain. T10.002
2026-10-12 17:16:13 In 0x9d2a604246abdd8b8a847049f114a670218d307a3160d37a0c4e567edde73fcb the attacker address sends 9,501,032.6 THEO to the orchestrator (0x599bfa1039c9e22603f15642b711d56be62071f4, traced by OAK), which passes it to the extraction contract (0x8f10b468b06c6fd214b65f87778827f7d113f996, traced by OAK). The contract sells it in 9 swaps into the THEO/USDC pair (0x182be47742b81777055d69c50e5c9d2fe803e938, traced by OAK) for 476,900 USDC, then routes the USDC through other pools into 189.44 WETH, which stays in the extraction contract. Defimon calls this one tx of a multi-tx dump campaign. —
2026-10-12 → 10-13 The proceeds end up as 700.8 ETH (~$1.76M), bridged from Base to Ethereum (PeckShield). The bridge used and any onward movement are not published. T7.003
2026-10-13 08:07:16 Defimon alert dates the loss to 2026-10-12 and names the TrustedRelayerIsm as the cause. —
2026-10-13 09:04:09 PeckShield reports the 19M mint, the swap to 700.8 ETH and the bridge to Ethereum. THEO is down 92% in 24 hours. —
2026-10-13 Autheo tells users not to buy, sell or bridge THEO while it investigates. No root-cause statement, fix or compensation has been published. response

Key addresses:

Fund flow

Traced by OAK on Base over the public-RPC fallback (Blockscout answered HTTP 403), as of 2026-10-30. One transaction is checked end to end (0x9d2a604246abdd8b8a847049f114a670218d307a3160d37a0c4e567edde73fcb, 2026-10-12 17:16:13 UTC). The bridge to Ethereum is relayed from PeckShield and not traced.

All transfers as a table (8)
Time (UTC)FromToAmountOAKTxBasis
2026-10-12T00:00ZTHEO HypERC20 warp route
0xebe516a20238f79dc20b07ead6768e08891ed309		Attacker (sender of the dump tx)
0x3048b4ee5a070f33b73e3401829847255079e0ad		19,000,000 THEO (unbacked mint)T10.002per defimontheo2026
2026-10-12T17:16ZAttacker (sender of the dump tx)
0x3048b4ee5a070f33b73e3401829847255079e0ad		Orchestrator
0x599bfa1039c9e22603f15642b711d56be62071f4		9,501,032.6 THEOT10.0020x9d2a604246abdd8b8a847049f114a670218d307a3160d37a0c4e567edde73fcbtraced by OAK
2026-10-12T17:16ZOrchestrator
0x599bfa1039c9e22603f15642b711d56be62071f4		Swap executor (shared, high-volume; Defimon calls it the extraction engine)
0x8f10b468b06c6fd214b65f87778827f7d113f996		9,501,032.6 THEOT10.0020x9d2a604246abdd8b8a847049f114a670218d307a3160d37a0c4e567edde73fcbtraced by OAK
2026-10-12T17:16ZTHEO/USDC pair
0x182be47742b81777055d69c50e5c9d2fe803e938		Swap executor (shared, high-volume; Defimon calls it the extraction engine)
0x8f10b468b06c6fd214b65f87778827f7d113f996		476,898.7 USDCT10.0020x9d2a604246abdd8b8a847049f114a670218d307a3160d37a0c4e567edde73fcbtraced by OAK
2026-10-12T17:16ZSwap executor (shared, high-volume; Defimon calls it the extraction engine)
0x8f10b468b06c6fd214b65f87778827f7d113f996		USDC to WETH/cbBTC pools and routers (a05de8fe…, 5d2806b9…, 3fe04a59…, 160d7e9d…, 42d4a22c…, 7c7420dd…, bee3211a…, 5b5562aa…, 4f5905e3…; cbBTC legs net to zero)476,898.7 USDCT10.0020x9d2a604246abdd8b8a847049f114a670218d307a3160d37a0c4e567edde73fcbtraced by OAK
2026-10-12T17:16ZUSDC to WETH/cbBTC pools and routers (a05de8fe…, 5d2806b9…, 3fe04a59…, 160d7e9d…, 42d4a22c…, 7c7420dd…, bee3211a…, 5b5562aa…, 4f5905e3…; cbBTC legs net to zero)Swap executor (shared, high-volume; Defimon calls it the extraction engine)
0x8f10b468b06c6fd214b65f87778827f7d113f996		189.44 WETHT10.0020x9d2a604246abdd8b8a847049f114a670218d307a3160d37a0c4e567edde73fcbtraced by OAK
2026-10-13T00:00ZSwap executor (shared, high-volume; Defimon calls it the extraction engine)
0x8f10b468b06c6fd214b65f87778827f7d113f996		Bridge Base to Ethereum (not published)700.8 ETHT7.003per peckshieldtheo2026
2026-10-13T00:00ZBridge Base to Ethereum (not published)Ethereum receiving address (not published)700.8 ETHT7.003per peckshieldtheo2026

What the trace adds beyond the sources:

  • New: the full addresses of the orchestrator, extraction contract and THEO/USDC pair (previously shortened), and that the attacker address 0x3048… signed the dump tx, so it held the unbacked THEO.
  • New: in that one tx 9,501,032.6 THEO went attacker, orchestrator, extraction contract. The contract sold all of it in 9 swaps to the pair for 476,898.7 USDC (matches the ~$476K in the timeline), then swapped the USDC through other pools into 189.44 WETH. The USDC and cbBTC legs net to zero; 189.44 WETH is left in the extraction contract and nothing leaves it inside the tx. The ~$700K figure in the sources fits this 189.44 WETH only loosely; it was not reconciled.
  • Caveat: 0x8f10… is not a one-off attacker contract. In a one-hour window on Base it moved USDC/WETH for about 1,700 other transactions, so its later outflows cannot be attributed to the attacker. WETH leaving it after 17:16 (public-RPC logs, 2026-10-12 to 10-13) goes to many unrelated addresses. No transfer could be tied to the 700.8 ETH bridge, so that step stays relayed.
  • Limit: the bridge, the Ethereum receiving address and the other 9.5M THEO of the 19M mint are not accounted for. The mint tx hash is published only as 0x4fdbbc5e…, so it could not be looked up. Native ETH (unwrapped WETH) is invisible over public RPC, which is probably where the bridge hop hides.
  • Limit: THEO is trusted: false in the tool (not allowlisted); it is the stolen token itself, not a counterfeit. Only this one transaction was checked, not the whole "multi-tx campaign".
  • Limit: the amounts are asset quantities only. USD figures (~$1.76M, ~$1.7M) are the sources' own.

Root-cause evidence

Public references

Techniques demonstrated (2)