Major Crypto Exchanges Bitfinex and OKEx Hit by Service Denial Attacks

Two top cryptocurrency exchanges have reported distributed denial-of-service (DDoS) attacks on their systems in the last 24 hours.

OKEx, which says it is based in Malta, has apparently suffered two attacks, one Thursday and one today, according to its CEO, Jay Hao. On his Weibo account Friday, Hao said the first attack was of a 200 gigabyte severity, but the second had doubled to 400 GB.

Despite the attacks, the exchange’s service is “largely unaffected,” he said. OKEx’s Twitter account has no warnings of interruptions this morning, apart from a brief interlude for a systems upgrade for its futures and options trading facility.

Apparently more severely affected is Bitfinex, which reported a suspected DDoS attack on Twitter Friday morning (UTC time).

The Hong Kong-headquartered platform’s trading services were offline for a period of under an hour, but at press time Bitfinex says services are back to normal.

“Today we were subject to a very sophisticated DDoS attack,” tweeted Bitfinex CTO Paulo Ardoino after the event. “The entire @bitfinex team worked really hard to completely annihilate it in a short period of time. All funds remained safe during the whole attack and high-trading-performance is now fully re-established.”

A DDoS attack attempts to overwhelm the hosting servers of an online service, using a flood of fake traffic from multiple computers to disrupt normal activity. A severe attack can take a service offline, or may cause slow responses for website users.

It’s not clear why two major exchanges have been targeted in this way at roughly the same time, or what the attackers hope to gain.