Impact
In Ethermint running versions before v0.7.3 or 0.8.x through 0.9.0, it is possible to take transaction fees from Cosmos SDK's FeeCollector for the current block by sending a custom-crafted MsgEthereumTx.
User funds and balances are safe.
Patches
This problem has been patched in Ethermint v0.7.3 on the mempool level.
The next version with state machine breaking changes (0.10.x) will patch it on the consensus level.
Workarounds
There are no tested workarounds. All software relying on Ethermint is recommended to upgrade to Ethermint v0.7.3 at their earliest possible convenience (or >0.10.0 if possible).
Credits
Thank you to @zb3 for reporting this issue on Cronos Immunefi Bug Bounty Program, to @cyril-crypto for reproducing the issue and to @yihuang and @thomas-nguy for patching the issue on the CheckTx (mempool) and the DeliverTx (consensus) levels.
For more information
If you have any questions or comments about this advisory:
zb3 Analyst
cyril-crypto Analyst
yihuang Analyst
thomas-nguy Analyst
Impact
In Ethermint running versions before v0.7.3 or 0.8.x through 0.9.0, it is possible to take transaction fees from Cosmos SDK's
FeeCollectorfor the current block by sending a custom-craftedMsgEthereumTx.User funds and balances are safe.
Patches
This problem has been patched in Ethermint v0.7.3 on the mempool level.
The next version with state machine breaking changes (0.10.x) will patch it on the consensus level.
Workarounds
There are no tested workarounds. All software relying on Ethermint is recommended to upgrade to Ethermint v0.7.3 at their earliest possible convenience (or >0.10.0 if possible).
Credits
Thank you to @zb3 for reporting this issue on Cronos Immunefi Bug Bounty Program, to @cyril-crypto for reproducing the issue and to @yihuang and @thomas-nguy for patching the issue on the CheckTx (mempool) and the DeliverTx (consensus) levels.
For more information
If you have any questions or comments about this advisory: