Hi,
Yes, you can dump LM and NTLM Hashes from SAM database. There are few ways
to do it. One is copy it off from the server, but this will require a
physical access to the server and a reboot. This method doesn't require any
permission at all, except physical access -- this is why physical access to
e.g. DC is very important. Next option is to use tools like pwdump2, but
this will require administrator privileges on computer where SAM database
is.
Once you have LM "Hashes" you can use tools like LC5 or older or some
on-line tools that will crack the hash to password.
What you can do about this is:
* Use NTLM Hash (LM Hash is vulnerable by design -- IBM designed it few
decades ago)
* Even with NTLM hash you have to use strong hard to guess passwords. If I
can run a dictionary attack against your passwords then it doesn't matter
what kind of Hash you use for your password storage
How to prevent Windows from storing a LAN manager hash of your password in
Active Directory and local SAM databases
http://support.microsoft.com/default.aspx?scid=kb;en-us;299656&Product=win2000
Account Passwords and Policies
http://www.microsoft.com/technet/prodtechnol/windowsserver2003/technologies/security/bpactlck.mspx
I hope this helps,
Mike