GHSA-3fp5-2xwh-fxm6
Evmos transaction execution not accounting for all state transition after interaction with precompiles
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| Go | github.com/evmos/evmos/v16 | < 17.0.0 | 17.0.0 |
| Go | github.com/evmos/evmos/v7 | <= 7.0.0 | no fix listed |
| Go | github.com/evmos/evmos/v6 | <= 6.0.4 | no fix listed |
| Go | github.com/evmos/evmos/v5 | <= 5.0.0 | no fix listed |
| Go | github.com/tharsis/evmos | <= 1.1.3 | no fix listed |
| Go | github.com/tharsis/evmos/v2 | <= 2.0.2 | no fix listed |
| Go | github.com/tharsis/evmos/v3 | <= 3.0.3 | no fix listed |
| Go | github.com/tharsis/evmos/v4 | <= 4.0.2 | no fix listed |
| Go | github.com/tharsis/evmos/v5 | <= 5.0.1 | no fix listed |
Details
As written in the advisory (Markdown source, shown as plain text).
### Context
- [`stateObject`](https://github.com/evmos/evmos/blob/b196a522ba4951890b40992e9f97aa610f8b5f9c/x/evm/statedb/state_object.go#L53-L68): represents the state of an account and is used to store its updates during a state transition. This is accomplished using two in memory Storage variables: `originStorage` and `dirtyStorage`
- [`StateDB`](https://github.com/evmos/evmos/blob/b196a522ba4951890b40992e9f97aa610f8b5f9c/x/evm/statedb/statedb.go#L33-L55): it is the general interface to retrieve accounts and holds a map of stateObjects.
### Impact
An external contributor, @iczc, discovered a way to mint arbitrary tokens due to the possibility to have two different states not in sync during the execution of a transaction. The exploit is based on the fact that to sync the Cosmos SDK state and the EVM one, we rely on the `stateDB.Commit()` method. When we call this method, we iterate though all the `dirtyStorage` and, **if and only if** it is different than the `originStorage`, we [set the new state](https://github.com/evmos/evmos/blob/b196a522ba4951890b40992e9f97aa610f8b5f9c/x/evm/statedb/statedb.go#L460-L465). Setting the new state means we update the Cosmos SDK KVStore.
Below, are described the steps to perform the attack:
- User send a tx to a smart contract (SC) that is calling a precompile.
- The SC perform a state transition of its state from A to B.
- The SC call the precompile.
- The SC perform a state transition of its state from B to A (revert of the previous).
- Once the transaction is executed, and the final **Commit** is performed, the state A will not be committed to the store because A is the same as `originStorage`.
If the tx is executed correctly, this is what happens at the store level:
- Initial state A is loaded from the KVStore and the dirtyStorage is set to B.
- Before running the precompile, the `dirtyStorage` is committed to the KVStore without changing the `originStorage`.
- Now, since we have a `dirtyStorage`, it is updated to the previous value A without changing the `originStorage`.
Since the tx executed correctly, the evm calls the commit to persist the dirtyStorage. However, since dirtyStorage is equal to originStorage, nothing will be changed.
To summarize, if a contract storage state that is the same before and after a transaction, but is changed during the transaction and can call an external contract after the change, it can be exploited to make the transaction similar to non-atomic. The vulnerability is **critical** since this could lead to drain of funds through creative SC interactions.
### Severity
Based on [ImmuneFi Severity Classification System](https://immunefisupport.zendesk.com/hc/en-us/articles/13332717597585-Severity-Classification-System) the severity was evaluated to `Critical` since the attack could have lead to direct loss of funds.
### Patches
The issue has been patched in versions >=V17.0.0.
## For more information
If you have any questions or comments about this advisory:
Reach out to the Core Team in [Discord](https://discord.gg/evmos)
Open a discussion in [evmos/evmos](https://github.com/evmos/evmos/discussions)
Email us at [[email protected]](mailto:[email protected]) for security questions
References
External links from the advisory. They lead to third-party sites.
- https://github.com/evmos/evmos/security/advisories/GHSA-3fp5-2xwh-fxm6
- https://nvd.nist.gov/vuln/detail/CVE-2024-32644
- https://github.com/evmos/evmos/commit/08982b5ee726b97bc50eaf58d1914829648b6a5f
- https://github.com/evmos/evmos
- https://github.com/evmos/evmos/blob/b196a522ba4951890b40992e9f97aa610f8b5f9c/x/evm/statedb/state_object.go#L53-L68
- https://github.com/evmos/evmos/blob/b196a522ba4951890b40992e9f97aa610f8b5f9c/x/evm/statedb/statedb.go#L33-L55
- https://github.com/evmos/evmos/blob/b196a522ba4951890b40992e9f97aa610f8b5f9c/x/evm/statedb/statedb.go#L460-L465