Htaccess can be used to manage multiple usernames/passwords, thereby enhancing information protection on the web server by controlling access through HTTP protocols. When used in conjunction with a browser encryption method such as SSL, it is possible to make htaccess authentication a robust method of protecting directories. However, out of the box, htaccess is prone to several problems, namely: packet-sniffing, IP hijacking, replay attacks, and brute force. Cryptography, (SSL and one-time pads) can solve all but one of these problems - brute forcing.
Brute forcing takes a number of forms, and is a well-known and well-used attack against htaccess. Brute force is usually a minimal knowledge attack, requiring only the URL for the password-protected directory to work. In their most malevolent form, brute force attacks simply check the headers returned by the server. If the program sees that its request was favorable (the server returned a 200 OK response), it will mark the password as being valid. This can wreak havoc on a server. It can even cause denial of service when the brute force program disconnects after viewing the headers (as the server is not allowed to print out the rest of the content and the daemon cannot kill its children efficiently.)
