Attackers determine that for every username that ends with an A, there is a similar username that ends in a digit.
What is the MOST likely explanation?
Explanation
OBJ-5.2: For years it has been a misguided attempt to use the suffix A to identify an administrator account, to keep them separate from the non-privileged accounts that administrators use when not requiring the elevated privileges; doing so makes these accounts more attractive to attackers. It is very unlikely that there are nine other usernames with the same surname and first initial (e.g. irvingp1 to irvingp9) for each user with an administrator account (irvingpa). Other than administrators, it is highly unusual to create a username for people in a specific role, especially for those who have a temporary position such as Acting Vice-President.