For your Windows XP Pro/W2003 computers you could use Software Restriction
Policies to create a hash rule for disallowed for any executables there are
for the different versions of messenger and or path rules. See the link
below for SRP
http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/rstrplcy.mspx
For Windows 2000 computers you could add the executable name to the
disallowed Windows application list using Group Policy under user
configuration/administrative templates/system though that is not as
effective as SRP because a user could bypass that setting by renaming the
executable.
http://support.microsoft.com/default.aspx?scid=kb;en-us;323525
Also it is best to use a firewall that is capable of having a default block
all rule for outbound access and then you define the allowed exceptions.
That will stop a lot of unauthorized internet applications though many have
the ability to tunnel through port 80 TCP which is the common http port used
for internet access. To help mitigate that you would have to add the IP
addresses of servers that the application uses to the blocked list in the
firewall or use a sophisticated firewall like ISA 2004 that can do deep
application http filtering and create rules to stop such access.
http://www.microsoft.com/technet/prodtechnol/isa/2004/plan/httpfiltering.mspx
--- ISA 2004 HTTP filtering
I almost forgot but for XP Pro and Windows 2003 you can also use Group
Policy to disable Windows Messenger for user or computer. Look at the
settings under user and computer configuration/administrative
templates/Windows Components/Windows messenger - do not allow Windows
Messenger to run and set it to enabled. --- Steve
