Actually it sits in %SystemRoot%\WinNT\drivers\etc
(where SystemRoot is frequently C:\Winnt or C:\Windows
Spyware such has been changing these.
The poster that recommended NTFS permissions has a
good idea but if you are the User who is (accidentlly)
running the spyware then the NTFS access control will
allow 'you' to edit it anyway.
If you use NTFS you may have to deny EVEN YOURSELF
the "write" (modify) permission but leave it readable to you
and the system.
You need to actively DENY write -- not just remove
everyone or whatever, since you are likely an admin and
you have Full Control to start. Be careful to own the
file or keep "permission change" permission in case you
mess it up.
Sometimes the old, and simple READ-ONLY (dos) file
attribute is sufficient and it protects you from making a
trivial mistake (copy, save a file over hosts.)
attrib +r %SystemRoot%\WinNT\drivers\etc\hosts
Spyware Blaster can "protect" you hosts file but that is
just storing a hidden copy.
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