If you asked me from September 2012 forward, the answer would change dramatically with WordPress Brute Force Attacks now exceeding 50% of all attacks being reported.
If you review your or your hosting provider reviews your web site’s access logs on a regular basis, you can tell if there are Brute Force attacks being attempted on your WordPress site by seeing multiple requests to access the file wp-login.php from the same IP address over and over again. Sometimes it might be a single request every x period of time; other times it might be scores of requests from the same IP address. By the way, are you or your provider regularly checking your web site access logs for abuse?
How can you protect yourself against WordPress Brute Force attacks?
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