From Rory in the official Chainlink telegram:
>Timed to occur in conjunction with our conference this past weekend, there was an unsuccessful attempt to spam the Chainlink network with irrelevant requests. This attempt lasted a few hours and failed to affect the performance of the network, which continued to deliver data to DeFi smart contracts as expected. The spam was mitigated when Chainlink nodes identified and adapted to it, while expending the necessary resources to continue operating despite the irrelevant requests. Node operators did pay additional ETH in gas costs to keep the network operational during the spam attempt because node operators properly prioritized their reputation scores and longer term standing in the Chainlink network over short term fee spikes, which is exactly what the network is purposefully designed to do within extreme network congestion and spam scenarios.
>We’d like to both commend and express our gratitude to the responsive, diligent and truly well run node operator teams that ensured their Chainlink nodes, and therefore the network, continued to operate correctly. This failed attempt to spam the network is a testament to how resilient Chainlink has grown to be and that its crypto-economic model for properly incentivizing node operators to continue operating in all network conditions is indeed functioning as designed.
I wonder who was behind this attack?