Re: Flaw in Microsoft Domain Account Caching Allows Local Workstation Admins to Temporarily Escalate Privileges and Login as Cached Domain Admin Accounts (2010-M$-002)

["Thor (Hammer of God)" <thor () hammerofgod com>]

Wow.  I guess you didn't read the post either.  I'm a bit surprised that a Sr. Network Engineer thinks that Group 
Policies "differentiate between local and Domain administrators."  You're making it sound like you think Group Policy 
application has some "magic permissions" or something, or that a "domain administrator" is a "bigger" administrator 
than the local administrator.

Group Policy loads from the client via the Group Policy Client service.   If I'm a local admin, I can just set my local 
system to not process group policy via the GPExtensions hive.  Done.  If I take the domain admin out of my local 
administrators, they can't do anything.  Done.  

How exactly do you think this is problematic for "shops that differentiate between desktop support and AD support"?  
(whatever that means).

t

> -----Original Message-----
> From: full-disclosure-bounces () lists grok org uk [mailto:full-disclosure-
> bounces () lists grok org uk] On Behalf Of George Carlson
> Sent: Friday, December 10, 2010 10:12 AM
> To: bugtraq () securityfocus com; full-disclosure () lists grok org uk
> Subject: Re: [Full-disclosure] Flaw in Microsoft Domain Account Caching Allows
> Local Workstation Admins to Temporarily Escalate Privileges and Login as
> Cached Domain Admin Accounts (2010-M$-002)
>
> Your objections are mostly true in a normal sense.  However, it is not true
> when Group Policy is taken into account.  Group Policies differentiate
> between local and Domain administrators and so this vulnerability is
> problematic for shops that differentiate between desktop support and AD
> support.
>
>
> George Carlson
> Sr. Network Engineer
> (804) 423-7430
>
>
> -----Original Message-----
> From: Stefan Kanthak [mailto:stefan.kanthak () nexgo de]
> Sent: Friday, December 10, 2010 11:30 AM
> To: bugtraq () securityfocus com; full-disclosure () lists grok org uk
> Cc: stenoplasma () exploitdevelopment com
> Subject: Re: Flaw in Microsoft Domain Account Caching Allows Local
> Workstation Admins to Temporarily Escalate Privileges and Login as Cached
> Domain Admin Accounts (2010-M$-002)
>
> "StenoPlasma @ www.ExploitDevelopment.com" wrote:
>
> Much ado about nothing!
>
> > TITLE:
> > Flaw in Microsoft Domain Account Caching Allows Local Workstation
> > Admins to Temporarily Escalate Privileges and Login as Cached Domain
> > Admin Accounts
>
> There is NO privilege escalation. A local administrator is an admistrator is an
> administrator...
>
> > SUMMARY AND IMPACT:
> > All versions of Microsoft Windows operating systems allow real-time
> > modifications to the Active Directory cached accounts listing stored
> > on all Active Directory domain workstations and servers. This allows
> > domain users that have local administrator privileges on domain assets
> > to modify their cached accounts to masquerade as other domain users
> > that have logged in to those domain assets. This will allow local
> > administrators to temporarily escalate their domain privileges on
> > domain workstations or servers.
>
> Wrong. The local administrator is already local administrator. There's nothing
> the elevate any more.
>
> > If the local administrator masquerades as an Active Directory Domain
> > Admin account, the modified cached account is now free to modify
> > system files and user account profiles using the identity of the
> > Domain Admin's account.
>
> There is no need to masquerade: the local administrator can perform all these
> modifications, and if s/he wishes, hide the tracks: turn off auditing before,
> clear audit/event logs afterwards, change the SID in the ACEs of all objects
> touched (SubInACL.Exe comes handy), ...
>
> Or: just change the "NoDefaultAdminOwner" setting. After that, all
> "Administrators" masquerade as "Administrators". uh-oh.
>
> > This includes
> > creating scripts to run as the Domain Admin account the next time that
> > they log in.
>
> Ridiculous.
> A local administrator can add any script/executable s/he wants to any
> "autostart" (scheduled task, registry, logon script, userinit, shell, ...).
> There's ABSOLUTELY no need to masquerade.
>
> > All files created will not be linked to your domain account in file
> > and folder access lists.
>
> ACEs can always be edited by a local administrator, see SubInACL.Exe, or
> TakeOwn.Exe.
>
> > All security access lists
> > will only show the Domain Admin's account once you log out of the
> > modified cached account. This leads to a number of security issues
> > that I will not attempt to identify in the article. One major issue is
> > the lack of non-repudiation. Editing files and other actions will be
> > completed as another user account. Event log entries for object access
> > will only be created if administrators are auditing successful access
> > to files (This will lead to enormous event log sizes).
>
> A local administrator can turn audit/event logs off, clear or modify them.
>
> Stefan
>
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