By default installation, Windows XP has a built-in Administrator account, which is equivalent to root or superuser privilege account in Linux or Unix, and contains no password. In other word, hacker or any people can simply key in Administrator as user name at the Windows Logon Welcome Screen prompt with blank password (no password) and get full administrative access as superuser to the Windows PC. Worse, most computer owners don’t even know such an Administrator account is actually existed, don’t even mention they will create or set a password for Administrator user account.
So this security vulnerability flaw provides an easy way to login into any Windows XP computer that the user forgets or simply does not set a password for the Administrator user ID. The problem is that in normal Windows XP Welcome Screen where you choose which user name you want to log onto, the Administrator user name is not displayed and is not shown. If you can’t choose or select the Administrator from the login screen, then how are you going to log-in with the Administrator account? The following video clip provides a simple hack and trick.
Video no longer available
Basically, at Windows XP Welcom Screen, simply press Ctrl + Alt + Del keys sequence together twice, and you will be shown a “Log On to Windows” menu which you can specify User Name and Password. In the User Name text box, key in Administrator and leave the Password field blank. Then press Enter or click on OK. If there is not password protects the Administrator account, or blank password is set, then you will be able to access the Windows with full administrative privileges as Administrator.