blockmason credit-protocol UCAC CreditProtocol.sol executeUcacTx denial of service

Vulnerability

The vulnerability resides in the executeUcacTx function of the contracts/CreditProtocol.sol file, part of the UCAC Handler component. This function is inexpensive and unauthenticated, and it increments the transaction counter for a UCAC without performing an actual transaction, up to that UCAC's transaction limit. The product does not use versioning, and affected versions are unsupported. The patch changes the function visibility from public to private [2].

Exploitation

An attacker can call executeUcacTx repeatedly without any authentication, continuously increasing the transaction counter and preventing legitimate transactions from being processed. The attack can be maintained indefinitely. The cost to perform the attack depends on the amount of tokens staked in the UCAC; fewer staked tokens make the attack cheaper [1].

Impact

Successful exploitation results in a denial of service (DoS) on a UCAC, blocking legitimate transactions. This may incentivize stakeholders to unstake their tokens, further reducing the cost of the attack [1].

Mitigation

The fix is commit 082e01f18707ef995e80ebe97fcedb229a55efc5, which changes executeUcacTx to private [2]. The repository was archived in July 2019 and is no longer supported. Users should apply the patch or migrate away from the unsupported product. No complete workaround is provided; staking more tokens increases attack cost but does not eliminate the vulnerability [1].