Password reuse and easy-to-guess passwords. Most of the time, it's not even the users themselves who are to blame but non-sensical password policies (like "Pass

Password reuse and easy-to-guess passwords. Most of the time, it's not even the users themselves who are to blame but non-sensical password policies (like "Password must contain characters XYZ and be no longer than 8 characters" and "Password must be renewed after 30 days.").