GHSA-w5w5-2882-47pc github.com/cosmos/cosmos-sdk's x/crisis does not charge ConstantFee
Attackers can spam invariant checks without paying the required constant fee, causing excessive CPU usage and potential denial of service on validator nodes.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is GHSA-w5w5-2882-47pc?
GHSA-w5w5-2882-47pc is a denial of service vulnerability in github.com/cosmos/cosmos-sdk, published on 30 Jun 2023. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
x/crisis does not charge ConstantFee
Impact
If a transaction is sent to the x/crisis module to check an invariant, the ConstantFee parameter of the chain is NOT charged. All versions of the x/crisis module are affected on all versions of the Cosmos SDK.
Details
The x/crisis module is supposed to allow anyone to halt a chain in the event of a violated invariant by sending a MsgVerifyInvariant with the name of the invariant. Processing this message takes extra processing power hence a ConstantFee was introduced on the chain that is charged as extra from the reporter for the extra computational work. This is supposed to avert spammers on the chain making nodes do extra computations using this transaction. By not charging the ConstantFee, the transactions related to invariant checking are relatively cheaper compared to the computational need and other transactions.
That said, the submitter still has to pay the transaction fee to put the transaction on the network, hence using this weakness for spamming is limited by the usual mechanisms.
Synthetic testing showed up to a 20% increase in CPU usage on a validator node that is spammed by hundreds of MsgVerifyInvariant messages which still makes this an expensive operation to carry out on a live blockchain network.
Patches
The ConstantFee charge of the x/crisis module will either be fixed or disabled in an upcoming regular release of the Cosmos SDK.
The x/crisis module was originally intended to allow chains to halt rather than continue with some unknown behavior in the case of an invariant violation (safety over liveness). However, as chains mature, and especially as the potential cost of halting increases, chains should consider carefully what invariants they really want to halt for, and what invariants are just sort of helpful sanity checks.
The SDK team is working on new modules that allow chain developers to fine-tune the chain invariants and the necessary actions.
Hence, the decision was made that the x/crisis module will be deprecated when new modules take over its responsibilities.
Workarounds
There is no workaround posted. Validators are advised to leave some extra computing room on their servers for possible spamming scenarios. (This is a good measure in any case.)
References
SDK developer epic about invariant checking: https://github.com/cosmos/cosmos-sdk/issues/15706
Which versions are affected by GHSA-w5w5-2882-47pc?
3 open source packages ship an affected version, including github.com/cosmos/cosmos-sdk.
| Package | Affected | Fixed in |
|---|---|---|
github.com/cosmos/cosmos-sdk Go | All versions | None |
github.com/cosmos/cosmos-sdk Go | All versions to 0.50.0-alpha.1 | None |
github.com/cosmos/cosmos-sdk Go | All versions to 0.50.0-alpha.1 | None |
How do I fix GHSA-w5w5-2882-47pc?
No fix has been published for GHSA-w5w5-2882-47pc yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is GHSA-w5w5-2882-47pc being exploited?
There is no known exploitation of GHSA-w5w5-2882-47pc in the wild and no public exploit code.
Sources
Also known as GO-2023-1881.