We are currently experiencing issues and investigating the cause. We'll update this post as we get more information.
UPDATE 20:46: Services have returned to normal. We have identified and blocked incoming traffic which was causing our load balancers to fail. We are currently investigating the structure of the requests to determine why they caused a denial of service and once we have determined this we can put measures in place to prevent this from reoccurring. Apologies for any inconvenience.
UPDATE 21:49: The malicious traffic has returned from another address - we are diagnosing and hope to have it blocked as soon as we can.
UPDATE 22:41: We have identified the vulnerability that has been exploited that caused the denial-of-service situation earlier tonight. We are upgrading the relevant software which should protect against further attacks.
UPDATE 00:32: We have now successfully updated and reconfigured the relevant software packages and configuration files and have tested successfully that we are no longer vulnerable to this susceptibility.