In September a iranian cloud service provider named ArvanCloud reported that a number of digital currency websites experienced a DDOS attack and the three victim named were arzjoo.com and excoino.com and avalpardakht.com. The attack on Arzjoo was the greatest and started on 9th September as a DDOS attack on layer 7. DDOS attacks can take place at layer 3 and layer 4 and layer 7. The layer 7 or application layer DDOS is typically the most complex and floods the network and servers with a very high volume of traffic. An ArvanCLoud employee said that the number of requests reached 26 million a minute in the peak of the DDOS and the number of bots used in the attack was more than 15,000. More technical details are available at this website .
There are reports in the media that the attacker demanded money from the victim in order to stop the attack but it is unclear whether any money was paid.