Resources

People often ask me "How did you learn how to hack?" The answer: by reading. This page is a collection of the blog posts and other articles that I have accumulated over the years of my journey. Enjoy!

Bridges are an important piece of the blockchain ecosystem. Being able to move assets from one chain to another is a necessary requirement in the modern web3 space. However, doing bridges securely is difficult to do. In Cosmos, interblockchain communication (IBC) allows for Cosmos blockchains to talk together in a standardized format. In this article, the authors discuss bridge security and how to make IBC more secure.

Most security is put into the pre deployment of applications, such as pentests, code review and more. However, equal importance needs to be on the post-deployment protections. The authors mention four different mechanisms for on-chain post-deployment: circuit breakers, rate limits, settlement delayers and redundancy.

Circuit breakers simply pause a system when certain conditions occur or manually. This acts as a kill switch to be able to stop functionality when something bad is happening. The Cosmos SDK circuit module is a good example of this but it must be manually done and it's per message.

Rate limits disable functionality once a threshold has been passed. This can be a value rate limit such as a dollar amount or a volume rate limit. The second one is similar to API rate limits. This helps to limit the damage of attacks but doesn't prevent them entirely.

Delayers impose a delay window between certain transactions. This allows for incident response a time window to revert things if they are malicious. For instance, a 1hr delay may be imposed on a transaction of $1M or more. This is common on governance proposals but can be used in other places as well.

Bridge Redundancy Protocols are a consist relay of message over several bridge protocols. If one is effected by a bug, that doesn't matter! To me, having diversity in software is good, like how JumpCrypto is making an alternative validator for Solana.

The focus of the article was how the Osmosis blockchain implemented rate limiting on IBC. They have a rate limit on the amount of token assets that can be moved into the ecosystem. This is done with by static periods and net flow of assets moving. This rate limiting is implemented in a CosmWasm smart contract that interacts with the IBC middleware package as a wrapper around ICS20.

To be more specific on the Cosmos side, the rate limits are implemented on a given channel and denom. This allows for a standard transfer to occur between two blockchains, without interfering with others. These rate limits measure the inflow and outflow of tokens on a given channel. These are setup in different intervals but appear to be configurable.

There are other examples of rate limiting. On the Stride Cosmos SDK blockchain, they do IBC rate limiting based upon the amount of tokens transferred on a channel for a 24 hour window. The Wormhole governor, after a large hack in 2022, implemented functionality as well. They have two types of transactions: small and large. A large transaction has a finality delay of 24 hours while both transaction types of a daily quoted of funds that can be sent.

Overall, good post on different on chain protections can be done to reduce the risk.