You are getting attacked by this server? No panic, there are a few scenarios why this is happening:

1. We are conducting an authorized penetration that has been requested by your IT department
2. We are trying to win some bug bounty (most likely targets from h1)
3. We accidentally stepped out of scope while doing 1) or 2)
4. Security research (Recently, some bXSS payloads were fired against a few thousand domains in order to see what comes back)

In any case, there are no evil intentions behind the attack.
If you think that none of these scenarios can be applied to your observations or if you simply want more information, feel free to contact abuse (at) h4x (d0t) tv