One of our forums got attacked by a server hosted at Keyweb AG (a German web hosting company). The attack was a spam bot testing if the forum was a moderated forum or not and the post looks like this:
If you got a forum on your own you should keep an eye open for posts from the Keyweb AG's IP number range: 62.141.48.0-62.141.55.255
If you can block access to your server based on IP address then you should put a block on IP 62.141.50.38 (hostname ns.km14016.keymachine.de) since that's the server spamming our forum.