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ID:

arbitrum-one-1166

Date:

Status:

Incident Count:

September 19, 2022

Near-Miss

3

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REKT

Contributor:

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web3rekt.com

KYC By:

KYC:

None

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Audit By:

Audits:

None

Loss Amount:

-

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Recovered:

-

Rewards:

538,000

Currency:

USD

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Key Indicators

Platform:

Type:

Category:

Method:

Data Sources:

Ethereum

Protocol

Layer 2

Rewards - Bug Bounties

Extended Method:

Logic error with postUgradeInit function allowing the exploiter to set his own bridge deposit address

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Days in Operation:

682

(1.87 Years)

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0xRiptide, a solidity whitehat, reported a bug bounty to ImmuneFi where he was paid 400 ETH, approx. $538k as of reported date.

The DelayedInbox contract uses a standard TransparentUpgradeableProxy pattern with a public initialize() function. This function includes an initializer modifier which in turn checks the first two storage slots on the proxy to see if the contract has already been initialized or is currently being initialized. However … pulling up etherscan showed that the bridge was set correctly but the sequencerInbox was uninitialized.

As it turns out the postUpgradeInit function wipes slots 0,1 & 2 and sets the bridge and allowListEnabled slots to new values — but leaves sequencerInbox and the two booleans set by the intializer modifier empty! At this point we can call the public initialize() function and set our own address as the bridge to accept all incoming ETH deposits

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