The blockchain was not under attack, it is similar to a DOS attack at the network level. Still not sure exactly how a killer packet was created, but a fix for the crashing is already updated in github. I estimate about 10% of nodes were affected.

If you are having crashes, just update and it should be fine. We are still testing the hotfix version, but the change was very small so it should be fine.

No funds were at risk, just annoyance of having to restart a node, but if you are in the process of syncing, it would likely make it much more difficult to do so as if it is crashed it wont sync.