The protocol doesn't check at all if account has already claimed, or moved (for attack, and defense).
Summary
move function in FaultDisputeGame contract doesn't check if account is already the claimant of parent claim.
Vulnerability Detail
Malicious actor create multiple defends or attacks for a game.
An account can create a defend and attack claim simultaneously for parent claim, so subgames can come from an account in a claim.
In addition, an account can have multiple defends for his root claim.
Indeed, creating claim for depend and attack doesn't check if msg.sender is related to claimant of parent claim and opposite claim.
petro1912
medium
The protocol doesn't check at all if account has already claimed, or moved (for attack, and defense).
Summary
movefunction inFaultDisputeGamecontract doesn't check if account is already the claimant of parent claim.Vulnerability Detail
Malicious actor create multiple defends or attacks for a game. An account can create a defend and attack claim simultaneously for parent claim, so subgames can come from an account in a claim. In addition, an account can have multiple defends for his root claim.
Indeed, creating claim for depend and attack doesn't check if msg.sender is related to claimant of parent claim and opposite claim.
Impact
It impacts fair claim.
Code Snippet
https://github.com/sherlock-audit/2024-02-optimism-2024/blob/main/optimism/packages/contracts-bedrock/src/dispute/FaultDisputeGame.sol#L226-L318
Tool used
Manual Review
Recommendation
To disable call to move function if account has already parent claim or opposite claim for its parent.
Duplicate of #122