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>]

What do you mean by "regular local administrator"?  You're a local admin, or you're not.  There are not degrees of 
local admin.  Why are you under the impression that there are things on a local system that the local admin should not 
have access to?  They can do anything they want to by design.  Are you under the impression that the Domain 
Administrator has different permissions on a local machine than the local administrator does?   The only reason a 
Domain Admin has admin rights by default on a domain workstation is because they simply belong to the local 
Administrators group.  If I, as a local admin, remove the domain admin account from my local Administrators group, then 
they will not be local admins.  In fact, I can just make the Domain Admin a "guest" on my workstation if I want to and 
there is nothing they can do about it. 

Sorry to be the bearer of bad news for you, but the local admin can do what they want to by design, and there is 
nothing that was "not intended by the software developer" here.  This is, of course, why the people at MSFT dismissed 
it as noted.

t

-----Original Message-----
From: StenoPlasma @ ExploitDevelopment [mailto:StenoPlasma () exploitdevelopment com] 
Sent: Thursday, December 09, 2010 6:13 PM
To: Thor (Hammer of God); 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)

T,

My article describes how to use the SECURITY registry hive to trick the Microsoft operating system in to performing an 
action that has a result that is not intended by the software developer.  This action is performed on the Active 
Directory logon account cache that regular local administrators should not have access to.  There are always other ways 
of doing things when it comes to this type of work.


Thank you,

-----------------------------------------------------
StenoPlasma at ExploitDevelopment.com
www.ExploitDevelopment.com
-----------------------------------------------------

-------- Original Message --------
> From: "Thor (Hammer of God)" <thor () hammerofgod com>
> Sent: Thursday, December 09, 2010 6:07 PM
> To: "stenoplasma () exploitdevelopment com" 
<stenoplasma () exploitdevelopment com>, "full-disclosure () lists grok org uk" 
<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$-002)
> Why all the trouble?  Just change the log files directly when logged 
> in
as the local admin.  It's a whole lot simpler, and you don't even need the domain administrator to have interactively 
logged into your workstation.  
Or is your point that local administrators are, um, local administrators?
> t
>
> > -----Original Message-----
> > From: full-disclosure-bounces () lists grok org uk
[mailto:full-disclosure-
> > bounces () lists grok org uk] On Behalf Of StenoPlasma @ 
> > www.ExploitDevelopment.com
> > Sent: Thursday, December 09, 2010 5:07 PM
> > To: bugtraq () securityfocus com; full-disclosure () lists grok org uk
> > Cc: stenoplasma () exploitdevelopment com
> > Subject: [Full-disclosure] Flaw in Microsoft Domain Account Caching
Allows
> > Local Workstation Admins to Temporarily Escalate Privileges and Login
as
> > Cached Domain Admin Accounts (2010-M$-002)
>
> -----------------------------------------------------------------------
> ---


> > www.ExploitDevelopment.com 2010-M$-002
>
> -----------------------------------------------------------------------
> ---


> > TITLE:
> > Flaw in Microsoft Domain Account Caching Allows Local Workstation 
> > Admins
to
> > Temporarily Escalate Privileges and Login as Cached Domain Admin
Accounts
> > 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. 
> > 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. This
includes
> > creating scripts to run as the Domain Admin account the next time 
> > that
they
> > log in. All files created will not be linked to your domain account 
> > in
file and
> > folder access lists. 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).
> >
> > DETAILS:
> > Prerequisites to exploit:
> >
> > #1: The user has a "Domain User" account that has administrative
privileges on
> > his/her workstation (This is a common configuration for both small 
> > and enterprise networks).
> > #2: The Microsoft Windows Active Directory domain has not disabled 
> > the
use
> > of Group Policy "Interactive logon: Number of previous logons to 
> > cache
(in
> > case domain controller is not available)". The default value for this
setting is
> > "10 logons".
> > #3: A domain/enterprise/schema/privileged administrator has logged in 
> > to
the
> > user's workstation at any time in the past (It would be very 
> > difficult
to not
> > have some type of admin from the domain login to a workstation for a 
> > number of reasons).
> >
> > Use the following steps to exploit this vulnerability:
> >
> > Step 1: Log in to your workstation using your Active Directory domain
account.
> > This account only needs to have administrative access to your
workstation.
> > Step 2: Create an interactive scheduled task to run a minute after
creating it.
> > This scheduled task brings up a command prompt as the NT
Authority\SYSTEM
> > account on Windows XP, and 2003. 'at 11:24 /interactive cmd.exe'. If
using
> > Windows Vista, 7, or 2008 Server, the attacker can use the psexec 
> > tool
(psexec
> > -i -s cmd.exe).
> > Step 3: Once the SYSTEM command prompt comes up, open regedit from 
> > the command line.
> > Step 4: Browse to 'HKEY_LOCAL_MACHINE\SECURITY\Cache'
> > Step 5: The list of "NL$1-10" records contain the cached active
directory
> > domain account sessions. To identify which account is yours, perform
the
> > following steps. Take note of all NL$ entries and entry content. 
> > Change
your
> > domain account password. Leave the SYSTEM shell and regedit 
> > application open. Log off the workstation, and then log back in to 
> > your domain
account.
> > Refresh the NL$ list. The NL$ line item that has been updated is your
domain
> > user's cached session.
> > Step 6: For this example, we will assume that your NL$ record is "NL$4"
> > Step 7: Double click on "NL$4". Take note of the four hex characters
that are
> > located in positions 1, 2, 3, and 4 on line 3 of the hex data.
> > Step 8: For this example, the hex characters are "5a 04". This number 
> > is
the
> > Active Directory octet string representation of your domain account's 
> > objectSID (The user account unique section of your AD Security
Identifier).
> > Step 9: For this example, there is only one other cached account 
> > listed
in the
> > NL$ listing (NL$3). Double click on "NL$3". Take note of the four hex
characters
> > that are located in positions 1, 2, 3, and 4 on line 3 of the hex data.
> > Step 10: For this example, the hex characters are "59 04". This user
account is
> > "Domain\DomainAdminAcct".
> > Step 11: Double click on "NL$4". Replace your SID hex representation 
> > "5a
04",
> > with DomainAdminAcct's SID hex representation "59 04".
> > Step 12: *Important* Disconnect all physical network connections from
the
> > workstation.
> > Step 13: Log off of the domain account, then log back in to your 
> > domain account.
> > Step 14: You will now be logged in to your modified cached account 
> > that
is
> > really the Domain Admin's account.
> > Step 15: You are now free to modify system files and user account
profiles
> > using the identity of the Domain Admin's account. This includes
creating
> > scripts to run as the Domain Admin account the next time that they 
> > log
in. All
> > files created will not be linked to your domain account. All security
access lists
> > will only show the Domain Admin's account once you log out of the
modified
> > cached account.
> > Step 16: All actions taken are indeed logged in the Security Event 
> > Log,
but all
> > actions are shown as being completed by "Domain\DomainAdminAcct".
> > Deeper inspection of event logs will show inside the login and logout
events
> > for your modified cached account, your actual user name is listed 
> > inside
the
> > event, but not in the Security Event Log Viewer listing. 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). These
events will
> > be listed as being performed as "Domain\DomainAdminAcct" in the event
log
> > viewer, but deeper inspection will show your true user name.
> >
> > VULNERABLE PRODUCTS:
> > All patch levels of Windows 2003 Server, Windows XP, Windows Vista, 
> > Windows 7, and Windows 2008 Server.
> >
> > REFERENCES AND ADDITIONAL INFORMATION:
> > N/A
> >
> > CREDITS:
> > StenoPlasma (at) ExploitDevelopment.com
> >
> > TIMELINE:
> > Discovery: December 4, 2010
> > Vendor Notified: December 7, 2010
> > Vendor Fixed: N/A
> > Vendor Dismissed: December 9, 2010
> > Vendor Notified of Disclosure: December 9, 2010
> > Disclosed: December 9, 2010
> >
> > VENDOR URL:
> > http://www.microsoft.com
> >
> > ADVISORY URL:
> > http://www.ExploitDevelopment.com/Vulnerabilities/2010-M$-002.html
> >
> > VENDOR ADVISORY URL:
> > N/A
> >
> >
> > -------------------------------------------------------------
> > StenoPlasma at ExploitDevelopment.com www.ExploitDevelopment.com
> > -------------------------------------------------------------
> >
> > _______________________________________________
> > Full-Disclosure - We believe in it.
> > Charter: http://lists.grok.org.uk/full-disclosure-charter.html
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