#47091 [SC-Insight] `setWorkAddress()` enables front-running attacks to hijack work addresses

Submitted on Jun 8th 2025 at 21:28:27 UTC by @danvinci_20 for Audit Comp | Flare | FAssets

• Report ID: #47091

• Report Type: Smart Contract

• Report severity: Insight

• Target: https://github.com/flare-foundation/fassets/blob/main/contracts/assetManager/implementation/AgentOwnerRegistry.sol

• Impacts:

  • Griefing (e.g. no profit motive for an attacker, but damage to the users or the protocol)

Description

Description

The AgentOwnerRegistry contract implements a setWorkAddress() function that allows an agent to designate a secondary "work" address associated with their management address. However, the current implementation does not sufficiently validate ownership or authority over the work address, creating a front-running vector that allows malicious agents with no potential risk (active vault) to hijack work addresses before legitimate owners can claim them.

This introduces a critical denial-of-service condition and opens up potential for targeted griefing attacks against agents attempting to onboard or reconfigure their setup.

function setWorkAddress(address _ownerWorkAddress) external {
    require(isWhitelisted(msg.sender),
        "agent not whitelisted");
    require(_ownerWorkAddress == address(0) || workToMgmtAddress[_ownerWorkAddress] == address(0),
        "work address in use");
    // ...
}

The function checks that the work address is currently unused, creating a room for hijacking the work address of legitimate agent and preventing them for setting their configuration.

Impact Details

Malicious agent Alice can keep frontrunning whitelisted agent Bob when she notice Bob wants to set work address to specific value. This leads to denial-of-service attack on Bob indefinitely.

Recommendations

I think it's better to introduce an off-chain mechanism to oversee the setting of the workAddress rather than allowing a specific agent to set up the workAddress from their end, this gives a constraint to random and frequent change of the workAddress.

Proof of Concept

Proof of Concept

Consider this straightforward attack scenario:

1. A legitimate agent attempts to register their work address:

agent.setWorkAddress(0xLegitimateWorkAddress);

1. A malicious actor monitors the mempool and sees this transaction.

2. The malicious actor quickly front-runs the transaction:

attacker.setWorkAddress(0xLegitimateWorkAddress);

1. The original agent’s transaction reverts with "work address in use".

This allows the attacker to indefinitely block the legitimate agent from using their desired work address.