Update Oct. 19, 2016, 2:20 pm PST: The gas limit is now below 2 million.
Since the second annual Ethereum event in September 2016, Devcon2, the Ethereum network has fallen victim to numerous attacks. The team behind Ethereum joined together to counter these attacks and retain the health of the network. When constant updates to the network were not mitigating these attacks, the Ethereum Foundation realized that they must create another hard fork to fully thwart the attacker. The hard fork was scheduled for the 2463000 block which took place on Tuesday, October 18, 2016 (PST).
Even though the hard fork occurred seamlessly yesterday and the health of the network has been improving, there is still an ongoing attack that is increasing block processing times on certain blocks. Hudson Jameson of the Etherum Foundation took to reddit to ask for help from the miners to lower the gas limit target to 2 million.
Hudson Jameson states:
“Mitigation strategies are being investigated. In order to subvert some of the negative affects of the current attack, we are asking miners to lower their gas limit target to 2 million.”
Vitalik Buterin, Founder of Ethereum weighed in as well:
“To clarify, the attack is based on making a large number of state reads with BALANCE. This was fixed by previous caching changes, but unfortunately the state is currently too big for caches to work well. A successful hard fork round two would resolve this for the short and medium term as it would make the state possible to put in memory again, but in the mean time we are also working on improvements to how state is read from disk that should further reduce disk reading times.
There is another weaker attack using the EXP opcode; this will also be fixed by HF round 2.
EDIT: more info on the "improvements to how state is read" - basically, the idea is to store an on-disk cache of address => account RLP object, so that it can be accessed directly instead of going through O(log(n)) trie nodes. Something like this is definitely needed in the long term, as we can't count on the state being memory-sized forever.”
ShapeShift has temporarily removed Ethereum assets from their exchange due to the attack.
ETHNews will stay on top of this story and update it as needed. Please stay tuned.