Protect/prevent Unix passwd/shadow and Windows SAM from being copied out

There's a discussion internally within our corporate if it's a concern that an internal staff attempts to copy out
SAM & passwd  and then run a password cracking tool on it.

Q1:
Is this a valid concern?

Q2:
In DoD B2 (or is it C2), the file containing hashed passwd  'vanishes' : is the purpose to prevent someone from
copying out the hashes for cracking?  Or what's the purpose of doing this?

Q3:
What are the measures we can put in place to prevent internal staff from making cracking attempts on SAM
& a Unix file containing the hashed passwords?  Should stronger hash (what's the current best practice?)  or
encryption be used?
sunhuxAsked:
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sunhuxAuthor Commented:
We thought of enabling Auditing of these files but these files are being accessed frequently to authenticate users.
Is there any way of auditing/logging it so that we only capture the genuine attempts to copy out these files ?
Dr. KlahnPrincipal Software EngineerCommented:
Q1:  Yes.

Q3:  There's a relatively simple mitigation nobody ever uses.  Have anyone with sensitive access individually background investigated and commercially bonded.  (A blanket position bond might be acceptable as the bar for claim is lower; but imo don't settle for that as it puts the burden on the company.)  Anyone who can't be bonded should not be in that position, or indeed any position in your organization.
sunhuxAuthor Commented:
on the Q3's reply, we're looking more in terms of mitigating from systems perspective & not from process/bonding/policy perspective.

Would placing an audit logging help & how can we configure it such that we don't get false positives?

So, using DoD's B2 (or is it C2) method is the way to go?
Shaun VermaakTechnical SpecialistCommented:
I primarily focus on MS but the principals translate

Should stronger hash (what's the current best practice?)  or encryption be used?
Both. Strong hashes project compromised hashes (except pass-the-hash) and encryption protects the SAM from offline/physical attacks.

The biggest security risk, however, is over-permission. Even in an environment with 100k endpoints, there should not be more than 2 or 3 domain admins. You can use Admin on the device to shadow copy SAM and crack offline.
https://www.experts-exchange.com/articles/29569/How-to-extract-hashes-from-IFM-backup.html
and a proper delegation model must be implemented
https://www.experts-exchange.com/articles/29366/Delegation-the-proper-way.html
and devices isolated
https://www.experts-exchange.com/articles/29515/Active-Directory-Simple-Tier-Isolation.html

I do not even need to carry rainbow table with me because I can crack hashes in the cloud
http://hashkiller.co.uk/md5-decrypter.aspx

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tfewsterCommented:
It;s late, but I'll add my 2c
Q1: Not really. If someone has access to the hashed password file, they already have Admin/root access, at least temporarily. There are better things to worry about - logging and auditing, for example.
Q3: SHA256 + salting is easy to implement and, in my opinion, makes the hashes pretty much immune to cracking or rainbow tables.

Look at the real Risk to the company first - i.e. how likely is (something) to happen, and what would be the impact?
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