ASA-2024-004: Default configuration param for Evidence may limit window of validity
ASA-2024-004: Default configuration param for Evidence may limit window of validity
Component: CometBFT
Criticality: Low
Affected versions: All
Affected users: Validators, Chain Builders + Maintainers
Summary
A default configuration in CometBFT has been found to be small for common use cases, and may prevent the slashing mechanism from working in specific cases. The default values for EvidenceParams.MaxAgeNumBlocks and EvidenceParams.MaxAgeDuration consensus parameters may not be sufficient for common use cases to provide coverage for the entire unbonding period for a chain (Staking.UnbondingTime). If the conditions of both of these parameters are exceeded, evidence may be prematurely expired and considered no longer valid, potentially allowing for unpunished Byzantine behavior if evidence is discovered outside of that window.
Next Steps for Chains and Validators
It is recommended that chain ecosystems and their maintainers set the consensus parameters EvidenceParams.MaxAgeNumBlocks and EvidenceParams.MaxAgeDuration to values appropriate for their use case:
EvidenceParams.MaxAgeDuration (set in nanoseconds) should exceed the duration of the chain’s unbonding periodEvidenceParams.MaxAgeNumBlocks should exceed the number of estimated blocks that will be produced by your chain throughout the unbonding period
For more information about evidence in CometBFT, please see: https://docs.cometbft.com/v0.37/spec/consensus/evidence.
For more information about the cosmos-sdk x/staking and x/slashing modules, and UnbondingTime parameter, please see: https://docs.cosmos.network/v0.50/build/modules/staking and https://docs.cosmos.network/v0.50/build/modules/slashing.
CometBFT is designed to be configurable by chains, and implements many different configuration variables and parameters to allow chain developers, validators, node operators, and chain participants to customize it best to their use case.
As more chains adopt the Interchain Stack for new and cutting-edge use cases, the CometBFT team recommends that all chains regularly evaluate their consensus parameters and configurations to ensure they meet the needs of their ecosystem as their networks mature.
A Github Security Advisory for this issue is available in the [CometBFT repository](https://github.com/cometbft/cometbft/security/advisories/GHSA-555p-m4v6-cqxv). For more information about CometBFT, see https://docs.cometbft.com/.
This issue was reported to the Cosmos Bug Bounty Program on HackerOne on February 15, 2024. If you believe you have found a bug in the Interchain Stack or would like to contribute to the program by reporting a bug, please see https://hackerone.com/cosmos.
