Over 300 blocks were rolled back in the course of the 51% attack.
Anonymous cryptocurrency Firo — formerly known as Zcoin— is the latest Proof-of-Work coin to suffer a 51% attack.
Tweeting
on Wednesday, Firo revealed that the protocol had come under a 51%
attack and advised holders to pause all transactions until the network
returns to a normal state.
The attack reportedly came to light when users reported that
previously confirmed transactions had become unconfirmed. This was
apparently the result of a blockchain reorganization attack initiated by
the attacker.
According
to Binance CEO Changpeng Zhao, the blockchain reorg resulted in a
rollback of 306 blocks. Details of the attack shared by team members on
the project’s Telegram group showed the attacked “orphaned” confirmed transactions from the previous day.
At
publishing time, the Firo team says the attack has stopped. Commenting
on the economic cost of the attack, Firo project steward Reuben Yap told
Cointelegraph:
“Exchanges are the ones at a loss as the
attacker had deposited funds which have now been reversed because of the
51% attack. We are still working with exchanges to resolve the matter.
From what we know at the moment both Binance and Indodax were affected.”
Firo
stated that the attack was not due to a coding error. “We frequently
assess to see what kind of hash rate is easily rentable on MTP and it
never approached something that would have been able to pull off an
attack on this scale,” Yap said.
For the Firo team, the attack was
only possible because the project was yet to deploy Chainlocks on the
mainnet. A Chainlock is a secondary validation layer that reportedly
mitigates a 51% attack.
According to Yap, with Chainlocks
activated, an attacker would need to control at least half of all Firo
master nodes in addition to the usual 51% mining hash rate dominance.
Firo
has reportedly completed the testing protocols for Chainlocks and is
primed for its full deployment in the next few weeks. When integrated,
Chainlocks will be the latest protocol feature added to the project
after activating the Lelantus upgrade.
The
timing of the attack was suspicious, according to Yap, who said that
Firo is investigating possible motives. “To pull a double spend of this
magnitude, the attacker had also acquired significant amounts of Firo
legitimately,” he said, adding:
“The timing of the attack
is also weird given that MTP has been live on our chain for a long time
and several months have passed since first halving. To attack us when
we are so close to deploying chain locks seems strange.”
On the price side, Firo (FIRO) is down
almost 12% in the last 24 hours. This decline has interrupted a
positive 14-day trading period for FIRO but the privacy coin is still up
over 73% since the start of 2021.
Proof-of-Work blockchains with
significantly lower hash rates have fallen victim to 51% attacks on
several occasions. Back in 2020, Ethereum Classic suffered multiple 51% attacks with one such incident leading to the loss of about $5.6 million worth of ETC. Grin, another privacy-focused crypto also suffered a 51% attack in 2020.
source link : https://cointelegraph.com/news/privacy-focused-firo-cryptocurrency-suffers-51-attack
