Riot reveals League of Legends Clash was brought down by a DDoS attack last weekend

League of Legends Clash

League of Legends’ Clash mode has been hampered by minor tech gremlins now and then since launching a few years ago, but last weekend’s problems were more severe.

Riot Games’ League of Legends tech lead Brian Bossé revealed on Twitter this evening that Riot had been hit by a DDoS (distributed denial-of-service) attack.

Clash mode allows players to form five-person teams and take part in casual online cups in a bid to earn in-game goodies.

Players reported outages and problems with the mode last weekend, with login errors and some players left unable to play. This led to Riot cancelling matches and refunding tickets towards the end of Saturday January 16th and Sunday January 17th.

Brian explained: “The outages have been caused by malicious internet traffic, colloquially known as a “goddamn DDoS.” It’s worth clearing up that the issues affecting Clash over the weekend weren’t due to anything with Clash, just the timing of the attack.

“We use non-standard communication protocols for some of our software while most of the anti-DDoS technology development has focused on HTTP because the interwebs mostly is just webs. That means that we can’t always just reach for The Thing Everyone Does When DDoSed.”

“As can be seen, mitigating this new type of DDoS attack is a work in progress. A lot of network folks have been heads down figuring out how to filter out this traffic since the events over the weekend. It’s hard work, and I thank them profusely for it.”

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Brian went on to explain that Riot is working internally on some solutions, but cannot share specifics due to the risk of attackers using that information to tweak their attacks in the future.

You can see Brian’s full thread on Twitter here:

Clash was first announced back in 2018, but technical issues prevented Riot from rolling it out fully across its player base.

Clash properly launched in early 2020 and, despite some minor hitches, for the most part worked well – Esports News UK didn’t experience any issues playing most weekends when it was live last year.

Further reading: How I got on at Riot UK’s 5v5 Clash event with coaching from exceL Esports on a team with RossBoomSocks

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