According to F-Secure a new variant of NetSky has been discovered:
A new Netsky variant was found – Netsky.V. It does not send itself as an attachment but uses HTML emails which exploit vulnerability known as Microsoft Internet Explorer XML Page Object Type Validation Vulnerability and tries to download and execute itself from an infected host.
Source: Donna’s Security Flash
[Later] I found the patches that supposedly prevent Netsky and its variants.
MICROSOFT SECURITY BULLETINS – THAT HELP TO PREVENT INFECTION
Netsky.V relies on several unpatched vulnerablies as noted below:
http://www.microsoft.com/technet/security/bulletin/MS99-032.mspx
http://www.microsoft.com/technet/security/bulletin/MS03-032.mspx
http://www.microsoft.com/technet/security/bulletin/MS03-040.mspx
Source: Harry Waldron