Johannes Ullrich, an analyst at The SANS Institute in Washington, agreed that brute force attacks have been on the rise for a while, but he didn't see numbers as high as Alert Logic.

"Brute force attacks are amazingly successful and simple," he said. "They do not require any particular exploit, but just a script to automatically guess the right password. Over the last couple years, we see less of the classic brute force attacks where an attacker is guessing many passwords for a particular account. Instead, attackers try a small set of passwords -- even if they use a 100 or so -- against a large number of user names. This bypasses some of the lock-out policies companies put in place to prevent brute forcing.

"Targets of brute force attacks are SSH (Secure Shell), FTP and Windows networking among other services," he said.