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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)
From: "Thor (Hammer of God)" <thor () hammerofgod com>
Date: Sat, 11 Dec 2010 00:15:11 +0000

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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