Buffer overflow in Windows Explorer (explorer.exe) on Windows XP and 2003 allows user-assisted attackers to cause a denial of service (repeated crash) and possibly execute arbitrary code via a .url file with an InternetShortcut tag containing a long URL and a large number of "file:" specifiers.
By default Microsoft Windows XP Home Edition installs with a blank password for the Administrator account, which allows remote attackers to gain control of the computer.