I believe he was trying to exploit VBulletin. Some bulletin boards (ubb mainly) have issues with characters like that. I'd suggest you check your logs just to be safe and then upgrade to 2.3.0.
I used to run UBB on a site and it was exploited by a member with the same type of name. The mysql db was erased completely but we were luckly enough to have logs with recent IPs. We compared those IPs to the ones that were normal and just narrowed it down that way until we found out who this guy was. No unrecoverable damage was done, as the system was colocated and backed up nightly, but I'd definately check.