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Protecting the Automatic Logon Password


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Guest simple_user
Posted

Hi there,

I was trying to change the way of automatic logon.

I wrote simple executable using LSA to set password by LsaStorePrivateData

(). Then I deleted reg.key value ‘DefaultPassword’

I restarted PC (WindowsXP installed) but it didn’t get through – it show

log-on dialog and I have to enter password manually.

I thought that Winlogon should be able to retrieve ‘secret’ password and not

to look for ‘DefaultPassword’ value.

Do I missing something here? Any additional steps needs?

 

Regards,

Guest S. Pidgorny
Posted

I think automatic logon is designed to require the DefaultPassword value.

Therefore LSA private data won't help, as there is no setting that allow

system to use it for automatic logon (AFAIK).

 

What are you trying to achieve with this?

 

--

Svyatoslav Pidgorny, MS MVP - Security, MCSE

-= F1 is the key =-

 

* http://sl.mvps.org * http://msmvps.com/blogs/sp *

 

"simple_user" <simpleuser@discussions.microsoft.com> wrote in message

news:0503FFFA-B921-41A0-BCE0-5B8D3607BFA3@microsoft.com...

> Hi there,

> I was trying to change the way of automatic logon.

> I wrote simple executable using LSA to set password by LsaStorePrivateData

> (). Then I deleted reg.key value 'DefaultPassword'

> I restarted PC (WindowsXP installed) but it didn't get through - it show

> log-on dialog and I have to enter password manually.

> I thought that Winlogon should be able to retrieve 'secret' password and

> not

> to look for 'DefaultPassword' value.

> Do I missing something here? Any additional steps needs?

>

> Regards,

>

Guest simple_user
Posted

"S. Pidgorny <MVP>" wrote:

> I think automatic logon is designed to require the DefaultPassword value.

> Therefore LSA private data won't help, as there is no setting that allow

> system to use it for automatic logon (AFAIK).

>

> What are you trying to achieve with this?

>

> --

> Svyatoslav Pidgorny, MS MVP - Security, MCSE

> -= F1 is the key =-

>

> * http://sl.mvps.org * http://msmvps.com/blogs/sp *

>

> "simple_user" <simpleuser@discussions.microsoft.com> wrote in message

> news:0503FFFA-B921-41A0-BCE0-5B8D3607BFA3@microsoft.com...

> > Hi there,

> > I was trying to change the way of automatic logon.

> > I wrote simple executable using LSA to set password by LsaStorePrivateData

> > (). Then I deleted reg.key value 'DefaultPassword'

> > I restarted PC (WindowsXP installed) but it didn't get through - it show

> > log-on dialog and I have to enter password manually.

> > I thought that Winlogon should be able to retrieve 'secret' password and

> > not

> > to look for 'DefaultPassword' value.

> > Do I missing something here? Any additional steps needs?

> >

> > Regards,

> >

>

>

> Hi,

Idea is to protect automatic logon password. There is the article

(http://msdn2.microsoft.com/en-us/library/aa378826.aspx), which talks about

it. What I was trying to achieve is to remove plain text (DefaultPassword)

from the registry that it can’t be seen.

But at this point I’m not sure what exactly my steps should be in order to

do that ( trying to find more articles, so far not so good).

I might be wrong but it could be that I have to write custom dll in order to

perform auto logon. Any ideas or pointing to some direction are welcome ïŠ

Posted

The LSA password is used if you set autologon by running the "control

userpasswords2" applet. It is not used if you set autologon manually in the

winlogon registry key.

 

Was looking-into this for the next release of MyLogon, as I'd like to

integrate the setup into one applet instead of referring the user to the

Microsoft tool, as is presently done.

 

Having said that, the LSA is no longer secure, it has been cracked. Thus it

is questionable whether it's worth the effort of setting an LSA password.

Perhaps better just to make sure the autologon password is a throwaway one -

one which is not also used for secure services.

 

Basically, no password stored in the registry is safe, even if encrypted,

since it must be possible for the same computer to decrypt it by some means

or other, and if the system can decrypt it, then in principle an

Administrative user can too. The only safe stored password is a hashed one

(which is not suitable for autologon purposes)

 

Password revealers: http://nirsoft.net/

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