full-disclosure - 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)

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Date: Fri, 10 Dec 2010 15:47:51 +0000
From: "Thor (Hammer of God)" <thor@...merofgod.com>
To: Marsh Ray <marsh@...endedsubset.com>, Mike Vasquez <mike@...ihax.com>
Cc: "full-disclosure@...ts.grok.org.uk" <full-disclosure@...ts.grok.org.uk>
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)

Hey Marsh - I think he meant LSA not SAM.  With the SAM, you can brute force the local accounts.  But with the LSA, you can get NTLM hashes for active users and attempt to use those.   You'll typically see those types of attacks against XP boxes or Win2000 where NTLM is still being used as the default authentication protocol.  Nowadays, in the enterprise anyway, network auth will be Kerberos, and if not, NTLMv2.

But yes, PTH is a different animal than what is being described my StenoPlasma.

t

-----Original Message-----
From: full-disclosure-bounces@...ts.grok.org.uk [mailto:full-disclosure-bounces@...ts.grok.org.uk] On Behalf Of Marsh Ray
Sent: Thursday, December 09, 2010 11:34 PM
To: Mike Vasquez
Cc: 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)

On 12/09/2010 09:36 PM, Mike Vasquez wrote:
> You can dump the local cached hashes, take a domain admins,

My understanding is that after the target user has logged off, the hashes which remain are only sufficient to validate a correct password. 
I.e., they're like the classic /etc/passwd hashes but with decent salts. 
They could be used for dictionary attacks, but not with precomputed rainbow tables.

> and use a
> pass the hash attack, which has been around for a while, such as:
> Hernan Ochoa / http://oss.coresecurity.com/projects/pshtoolkit.htm

My understanding is that PTH is a technique allowing you to easily use a different kind of hash. The password-equivalent kind that would be copied from the credentials of a live logged-in session. In that sense, PTH on its own may not meet the formal definition of an 'attack', since you still need a way to capture the password-equivalent.

> I don't see this being any more concerning.  Whatever you do in the 
> above, is under the other account.  Granted, I may be missing 
> something, so enlighten me.

If you're a local admin, you can replace explorer.exe and access resources with the credentials of the logged-in user.

If you're a local admin, you can install a keylogger and trivially capture anyone's freaking plaintext password (local console or RDP sessions).

So don't type your Domain Admin password into an untrusted system. Duh!

Note that any system to which an untrusted party has unsupervised physical access is untrusted.

- Marsh

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_______________________________________________
Full-Disclosure - We believe in it.
Charter: http://lists.grok.org.uk/full-disclosure-charter.html
Hosted and sponsored by Secunia - http://secunia.com/