NT Security Alert: (was Re: NTDOM: SamLogon validation...)

Luke Kenneth Casson Leighton lkcl at switchboard.net
Tue Feb 3 16:37:53 GMT 1998

On Tue, 3 Feb 1998, Paul Ashton wrote:

> At 01:18 03/02/98 , Paul Ashton wrote:
> >From a quick look at a packet trace, the original client that wishes
> >to access a share does an SMB negotiate and receives an 8 byte challenge,
> >it then does a session setup & X with a 24 byte challenge response. The
> >The SMB server then forwards the challenge and the response to the PDC
> >without encryption. The PDC confirms whether the response was valid and
> >if so, returns the password hash to the SMB server (rc4 encrypted) so
> >that the SMB server could then forward the hash to other servers on
> >behalf of the client. 
> This means that anybody passively listening to the LAN can turn
> any NTLM challenge response sequence into a password equivalent!
> Just forward the challenge and response of a sniffed packet to an
> NT DC and it will send you the password equivalent.
> The only thing you need is access to a workstation trust account
> name and password. You will have this if you have administrative
> access to your own machine or if you listen to a workstation
> joining a domain for the first time.
> I think Luke's smbclient mods can be coded to exploit this. Luke?

yes, it could.  oh dear.  i'll implement "Network" Logons, first.  then
the code will be there.  two days, ok?


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