Varna is a new programming language being developed by the æternity team that will be used for writing smart contracts. It is anticipated to be similar to Bitcoin’s Script language. Since Varna contracts will not contain any loops and the gas cost for calls are bounded at compile time, this will help tremendously in mitigating the risks associated with accidentally draining an excessive amount of funds when interacting with the contract.
A very famous incident where funds were continuously drained maliciously through a smart contract was the case of The DAO hack. Built on top of the Ethereum blockchain, the DAO was a decentralized autonomous organization that raised approximately 11,500,000 ETH through crowdfunding in May of 2016 and had set a new record for the largest ever crowdfunding campaign in history. At that time, 11,500,000 ETH was worth around $150,000,000. Needless to say, the project never came to fruition due to the security vulnerability discovered in the smart contract.