ReviewsMicrosoft warns of new security threat in XP SP1.
Microsoft is warning consumers using Windows XP Service Pack 1 (SP1) and Windows 2000 SP4 that code has been published that could be used to launch denial-of-service (DoS) attacks.
According to the Microsoft security advisory, "the vulnerability could allow an attacker to levy a denial of service attack of limited duration" on Windows XP SP1 if the attacker has valid log-on credentials.
(CIO Today)