hash-injection/pass-the-hash countermeasure

[Danny Fullerton <dfullerton () mantor org>]

Hello,

I been aware of the hash-injection vulnerability in Windows
authentication system for some time but had no opportunity to further
investigate some effective countermeasures. All the information I found
was oriented toward the attack rather then the exposure and effective
solutions.

Some proposed to restrict user from getting administrator account on
there own workstation but I think there's too much canvas and exception
to only consider this method.

Others suggest using unique dedicated userid/passsword for every system
but didn’t mention any implementation detail. I guess this include a
procedural control dictating the way help desk and administrators use
those IDs (something enforcing proper use of the password like changing
its value after each use and ensuring accountability).

Some research notate that not all protocol generate “windows logon” but
all of this is unclear. Which protocol really use the ?safe? Kerberos
method, which will trigger an insecure “windows logon” (lm/ntml/ntmlv2)
and for what reason? From my understanding “Remote Desktop” would create
an unsafe “windows logon” every time, but I want to known why.

I heard the best way would be to have a "Kerberos only" option in
"HKEY_LOCAL_MACHINE\System\CurrentControlSet\control\LSA" among "level 5
- NTLNv2 only, level 4 - only NTLM and NTLMv2, ..." but this is only
possible if you can broke compatibility with older system and this is
not always possible in some environment... and by getting Microsoft to
do so.

How do people address this risk? Anyone have other ideas? I would like
to have your inputs before undertaking my own test, if found necessary.

Ref:
http://truesecurity.se/blogs/murray/archive/tags/hash+injection/default.aspx

thanks,

---
Danny Fullerton
Mantor Organization

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