Message-ID: <58DB1B68E62B9F448DF1A276B0886DF16EB719EC@EX2010.hammerofgod.com>
Date: Mon, 13 Dec 2010 20:20:46 +0000
From: "Thor (Hammer of God)" <thor@...merofgod.com>
To: Peter Setlak <petersetlak@...com>, Andrea Lee <andrea@...trap.net>
Cc: "full-disclosure@...ts.grok.org.uk" <full-disclosure@...ts.grok.org.uk>,
	"bugtraq@...urityfocus.com" <bugtraq@...urityfocus.com>,
	George Carlson <gcarlson@...s.edu>
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)

There is no "local admin" on a DC.

t

From: Peter Setlak [mailto:petersetlak@...com]
Sent: Monday, December 13, 2010 12:06 PM
To: Andrea Lee
Cc: Thor (Hammer of God); George Carlson; bugtraq@...urityfocus.com; full-disclosure@...ts.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)

?

OK, wrap up, are we talking about Domain Admins having local admin privs? Of course they do - that's the joy of having a domain, centralized management...

OR

Are we talking about local admins having domain admin privs?

The local admin would only have "temporary" domain admin privs if said local system was a DC. This is a given that the DC's local admin has equiv to domain admin, thus, you can only log in to a DC as domain admin to begin with once it has become a DC. I'm not sure of any situation where a local admin to say a member server would have domain admin privs unless the local admin were to be added to the domain admins group on that machine. Which, of course, one would need domain admin equiv privs in order to make such a change in the first place...

Perhaps in older, NT pre-SP4 boxes, if the local admin to all the boxes had the same username/password, and that same username/password combo were to have been on the NT box prior to it becoming the PDC, and, in turn, after the NT box became PDC, that username was added to the domain admins group then, perhaps all local admins across the domain would share in the delight of being mistaken as a domain admin but even then, I just gave myself a headache - we are talking pre or post WINS here? Are we getting workgroups confused with domains? Definitely, 2k and XP do not have this issue as accounts are stored in the AD using SSID's which are unique across machines - so - even if machine A & B & the DC had the same local admin username & password, local admin A doesn't have actual privs on B or the DC. It may appear as such because the user would type in the same username/password combo, but, the account itself is just a local admin on A, and B's is on B, and the DC, well, that is a domain admin (see above).

Maybe I should refrain from jumping in mid-thread?

Peter Setlak
petersetlak@...com<mailto:petersetlak@...com>
(315) 371-6611

Skype Me!<skype:petersetlak?chat> (Get Skype<http://www.skype.com/go/download>)

** SAVE A TREE!
(Please consider the environment before printing this email or its attachments...)

On Dec 13, 2010, at 12:12 PM, Andrea Lee wrote:


I hope I'm not just feeding the troll...

A local admin is an admin on one system. The domain admin is an admin
on all systems in the domain, including mission critical Windows
servers. With temporary domain admin privs, the local admin could log
into the AD and change permissions / passwords for another user or
another user, thus getting full admin rights on all systems for a long
period of time. Plus whatever havoc might be caused by having the
ability to change rights on fileshares to allow the new domain admin
to see confidential files..

I would expect that the intent is to use another flaw for a normal
user to become a local admin, and then jump to domain admin via this.

So yes. In an enterprise environment, the "domain administrator" is "bigger".

Cheers,

On Fri, Dec 10, 2010 at 4:15 PM, Thor (Hammer of God)
<thor@...merofgod.com<mailto:thor@...merofgod.com>> wrote:

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@...ts.grok.org.uk<mailto:full-disclosure-bounces@...ts.grok.org.uk> [mailto:full-disclosure-
bounces@...ts.grok.org.uk] On Behalf Of George Carlson
Sent: Friday, December 10, 2010 10:12 AM
To: bugtraq@...urityfocus.com<mailto:bugtraq@...urityfocus.com>; full-disclosure@...ts.grok.org.uk<mailto:full-disclosure@...ts.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@...go.de]
Sent: Friday, December 10, 2010 11:30 AM
To: bugtraq@...urityfocus.com<mailto:bugtraq@...urityfocus.com>; full-disclosure@...ts.grok.org.uk<mailto:full-disclosure@...ts.grok.org.uk>
Cc: stenoplasma@...loitdevelopment.com<mailto:stenoplasma@...loitdevelopment.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<http://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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