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Muster
Critical contracts can be upgraded by an EOA which could result in the loss of all funds.
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About
Muster Network is an Arbitrum Orbit L3 gaming chain aiming to transform digital ownership for brands and games while managing blockchain infrastructure and security.
Badges
About
Muster Network is an Arbitrum Orbit L3 gaming chain aiming to transform digital ownership for brands and games while managing blockchain infrastructure and security.
Why is the project listed in others?
Consequence: projects without a sufficiently decentralized set of challengers rely on few entities to safely update the state. A small set of challengers can collude with the proposer to finalize an invalid state, which can cause loss of funds.
Consequence: projects without a sufficiently decentralized data availability committee rely on few entities to safely attest data availability on Ethereum. A small set of entities can collude with the proposer to finalize an unavailable state, which can cause loss of funds.
Learn more about the recategorisation here.
2024 Aug 03 — 2025 Aug 02
Arbitrum OneFunds can be stolen if
Funds can be lost if
Users can be censored if
MEV can be extracted if
| SEQUENCER FAILURE | STATE VALIDATION | DATA AVAILABILITY | EXIT WINDOW | PROPOSER FAILURE | |
| Arbitrum One L2 | Self sequence | Fraud proofs (INT) | Onchain | 10d | Self propose |
| Muster L3 • Individual | Self sequence | Fraud proofs (INT) | External (DAC) | None | Self propose |
| Muster L3 • Combined | Self sequence | Fraud proofs (INT) | External (DAC) | None | Self propose |
No actor outside of the single Proposer can submit fraud proofs. Interactive proofs (INT) require multiple transactions over time to resolve. The challenge protocol can be subject to delay attacks. There is a 1d challenge period.
Proof construction relies fully on data that is NOT published onchain. There exists a Data Availability Committee (DAC) with a threshold of 1/1 that is tasked with protecting and supplying the data.
There is no window for users to exit in case of an unwanted regular upgrade since contracts are instantly upgradable.
Anyone can become a Proposer after 28d of inactivity from the currently whitelisted Proposers.
Set of parties responsible for signing and attesting to the availability of data.
There are no onchain assets at risk of being slashed in case of a data withholding attack, and the committee members are not publicly known.
There is no fraud detection mechanism in place. A data withholding attack can only be detected by nodes downloading the full data from the DA layer.
The committee does not meet basic security standards, either due to insufficient size, lack of member diversity, or poorly defined threshold parameters. The system lacks an effective DA bridge and it is reliant on the assumption of an honest sequencer, creating significant risks to data integrity and availability.
There is no delay in the upgradeability of the bridge. Users have no time to exit the system before the bridge implementation update is completed.
The relayer role is permissioned, and the DA bridge does not have a Security Council or a governance mechanism to propose new relayers. In case of relayer failure, the DA bridge will halt and be unable to recover without the intervention of a centralized entity.
Architecture
The DAC uses a data availability solution built on the AnyTrust protocol. It is composed of the following components:
- Sequencer Inbox: Main entry point for the Sequencer submitting transaction batches.
- Data Availability Committee (DAC): A group of members responsible for storing and providing data on demand.
- Data Availability Certificate (DACert): A commitment ensuring that data blobs are available without needing full data posting on the L1 chain.
Committee members run servers that support APIs for storing and retrieving data blobs. The Sequencer API allows the rollup Sequencer to submit data blobs for storage, while the REST API enables anyone to fetch data by hash. When the Sequencer produces a data batch, it sends the batch along with an expiration time to Committee members, who store it and sign it. Once enough signatures are collected, the Sequencer aggregates them into a valid DACert and posts it to the L1 chain inbox. If the Sequencer fails to collect enough signatures, it falls back to posting the full data to the L1 chain.
A DACert includes a hash of the data block, an expiration time, and proof that the required threshold of Committee members have signed off on the data. The proof consists of a hash of the Keyset used in signing, a bitmap indicating which members signed, and a BLS aggregated signature. L2 nodes reading from the sequencer inbox verify the certificate’s validity by checking the number of signers, the aggregated signature, and that the expiration time is at least two weeks ahead of the L2 timestamp. If the DACert is valid, it provides a proof that the corresponding data is available from honest committee members.
DA Bridge Architecture
The DA commitments are posted to the destination chain through the sequencer inbox, using the inbox as a DA bridge. The DA commitment consists of Data Availability Certificate (DACert), including a hash of the data block, an expiration time, and a proof that the required threshold of Committee members have signed off on the data. The sequencer distributes the data and collects signatures from Committee members offchain. Only the DACert is posted by the sequencer to the destination chain inbox (the DA bridge), achieving destination chain transaction ordering finality in a single onchain transaction.
Funds can be lost if a malicious committee attests to an invalid data availability certificate.
Funds can be lost if the bridge contract or its dependencies receive a malicious code upgrade. There is no delay on code upgrades.
Updates to the system state can be proposed and challenged by a set of whitelisted validators. If a state root passes the challenge period, it is optimistically considered correct and made actionable for withdrawals.
Validators propose state roots as children of a previous state root. A state root can have multiple conflicting children. State roots are referred to as “assertions” within the contracts. Each chain of assertions only requires one stake, and validators staked on assertions with a child are considered inactive and can either move their stake to a new node or withdraw it. The function used to propose a new assertion is the stakeOnNewAssertion function. The stake is currently set to 0.1 ETH, and it can be slashed if the proposal is proven incorrect via a fraud proof. The protocol allows such funds to be trustlessly pooled together if necessary. New nodes cannot be created faster than the minimum assertion period, currently set to 15m. An assertion without “rivals” can be confirmed after the challenge period has passed, currently set to 1d. If a rival is present, then it is checked that the assertion is the winner in the challenge protocol.
A challenge can be started between two siblings, i.e. two different state roots that share the same parent, by calling the createLayerZeroEdge function in the ChallengeManager contract. Edges represent assertions, or bisected assertions, within the challenge protocol. Challenges are played via a bisection game, where asserters and challengers play together to find the first instruction of disagreement. Such instruction is then executed onchain in the WASM OneStepProver contract to determine the winner. An edge can only be bisected when rivaled. The bisection process requires no new stake as their validity is checked against a parent “history root” that contains all intermediate states. An edge can also be confirmed if itself or its descendants spend enough time being unrivaled. Such time is set to 1d. If both actors play as slow as possible, the maximum time to confirm an edge is double such value, i.e. 2d. Due to the complexities of maintaining the history root, the challenge protocol is divided into 3 levels, where the lowest level represents assertions over blocks, the highest level represents assertions over single WASM instructions, and intermediate levels represent assertions over chunks of WASM instructions. When moving between levels, a new stake is required. Level 0 (block level) requires a stake of 0.0 ETH, level 1 requires a stake of 1.0 ETH, level 2 requires a stake of 1.0 ETH. The ratio between such stakes can be exploited to perform resource exhaustion attacks.
Funds can be stolen if an attacker successfully performs a resource exhaustion attack.
Arbitrum OneThe system has a centralized sequencer
While forcing transaction is open to anyone the system employs a privileged sequencer that has priority for submitting transaction batches and ordering transactions.
MEV can be extracted if the operator exploits their centralized position and frontruns user transactions.
Users can force any transaction
Because the state of the system is based on transactions submitted on the underlying host chain and anyone can submit their transactions there it allows the users to circumvent censorship by interacting with the smart contract on the host chain directly. After a delay of 1d in which a Sequencer has failed to include a transaction that was directly posted to the smart contract, it can be forcefully included by anyone on the host chain, which finalizes its ordering.
Buffered forced transactions
To force transactions from the host chain, users must first enqueue “delayed” messages in the “delayed” inbox of the Bridge contract. Only authorized Inboxes are allowed to enqueue delayed messages, and the so-called Inbox contract is the one used as the entry point by calling the sendMessage or sendMessageFromOrigin functions. If the centralized sequencer doesn’t process the request within some time bound, users can call the forceInclusion function on the SequencerInbox contract to include the message in the canonical chain. The time bound is defined to be the minimum between 1d and the time left in the delay buffer. The delay buffer gets replenished over time and gets consumed every time the sequencer doesn’t timely process a message. Only messages processed with a delay greater than 596523d 5h consume the buffer. The buffer is capped at 596523d 5h. The replenish rate is currently set at 1m every 20m. Even if the buffer is fully consumed, messages are still allowed to be delayed up to 596523d 5h.
Arbitrum OneRegular messaging
Autonomous exit
Users can (eventually) exit the system by pushing the transaction on L1 and providing the corresponding state root. The only way to prevent such withdrawal is via an upgrade.
EVM compatible smart contracts are supported
Arbitrum One uses Nitro technology that allows running fraud proofs by executing EVM code on top of WASM.
Arbitrum One
Roles:
Can submit transaction batches or commitments to the SequencerInbox contract on the host chain.
Can propose new state roots (called nodes) and challenge state roots on the host chain.
Actors:
- Can upgrade with no delay
- UpgradeExecutor UpgradeExecutor → ProxyAdmin
- Inbox UpgradeExecutor → ProxyAdmin
- EdgeChallengeManager UpgradeExecutor → ProxyAdmin
- RollupEventInbox UpgradeExecutor → ProxyAdmin
- Bridge UpgradeExecutor → ProxyAdmin
- Outbox UpgradeExecutor → ProxyAdmin
- RollupProxy UpgradeExecutor
- SequencerInbox UpgradeExecutor → ProxyAdmin
- Can interact with RollupProxy
- Pause and unpause and set important roles and parameters in the system contracts: Can delegate Sequencer management to a BatchPosterManager address, manage data availability and DACs, set the Sequencer-only window, introduce an allowList to the bridge and whitelist Inboxes/Outboxes UpgradeExecutor
- Can interact with SequencerInbox
- Add/remove batchPosters (Sequencers)
- A Sequencer - acting directly
Arbitrum One
Contract that implements the main challenge protocol logic of the fraud proof system.
- Roles:
- admin: ProxyAdmin; ultimately EOA 1
Central contract for the project’s configuration like its execution logic hash (wasmModuleRoot) and addresses of the other system contracts. Entry point for Proposers creating new assertions (state commitments) and Challengers submitting fraud proofs (In the Orbit stack, these two roles are both called Validators).
- Roles:
- admin: UpgradeExecutor; ultimately EOA 1
- getValidators: EOA 2
- owner: UpgradeExecutor; ultimately EOA 1
A sequencer (registered in this contract) can submit transaction batches or commitments here.
- Roles:
- admin: ProxyAdmin; ultimately EOA 1
- batchPosterManager: EOA 3
- batchPosters: EOA 3
Central contract defining the access control permissions for upgrading the system contract implementations.
- Roles:
- admin: ProxyAdmin; ultimately EOA 1
- executors: EOA 1
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.
- Roles:
- owner: UpgradeExecutor
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.
Helper contract sending configuration data over the bridge during the systems initialization.
- Roles:
- admin: ProxyAdmin; ultimately EOA 1
One of the modular contracts used for the last step of a fraud proof, which is simulated inside a WASM virtual machine.
Value Secured is calculated based on these smart contracts and tokens:
Contract managing Inboxes and Outboxes. It escrows ETH sent to L2.
The current deployment carries some associated risks:
Funds can be stolen if a contract receives a malicious code upgrade. There is no delay on code upgrades (CRITICAL).