If you have a blog, you need to install this plug-in immediately.
There is currently a major type of internet attack being waged by botnets against webservers running WordPress. These bots brute-force their way in past your password screen by making thousands of guesses until they gain entry. WordPress currently does not limit the number of incorrect password attempts. Until it does, you need a plug-in that provides the limiting.
There is currently a significant attack being launched at a large number of WordPress blogs across the Internet. The attacker is brute force attacking the WordPress administrative portals, using the username “admin” and trying thousands of passwords. It appears a botnet is being used to launch the attack and more than tens of thousands of unique IP addresses have been recorded attempting to hack WordPress installs.
One of the concerns of an attack like this is that the attacker is using a relatively weak botnet of home PCs in order to build a much larger botnet of beefy servers in preparation for a future attack. These larger machines can cause much more damage in DDoS attacks because the servers have large network connections and are capable of generating significant amounts of traffic. This is a similar tactic that was used to build the so-called itsoknoproblembro/Brobot botnet which, in the Fall of 2012, was behind the large attacks on US financial institutions.