The Unofficial NT Hack FAQ

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Section 09

The Registry

09-1. What is the Registry?
09-2. What are hives?
09-3. Why is the Registry like this and why do I care?
09-4. What do I do with a copy of SAM?

09-1. What is the Registry?

The Registry is the central core registrar for Windows NT. Each NT workstation for server has its own Registry, and each one contains info on the hardware and software of the computer it resides on. For example, comm port definitions, Ethernet card settings, desktop setting and profiles, and what a particular user can and cannot do are stored in the Registry. Remember those ugly system INI files in Windows 3.1? Well, they are all included with even more fun stuff into one big database called the Registry in NT.

Of interest to hackers is the fact that all access control and assorted parameters are located in the Registry. While I'm tempted to discuss just that portion of the Registry, I'll briefly cover everything for completeness but put the fun stuff up front.

The Registry contains thousands of individual items of data, and are grouped together into "keys" or some type of optional value. These keys are grouped together into subtrees -- placing like keys together and making copies of others into separate trees for more convenient system access.

The Registry is divided into four separate subtrees. These subtrees are called HKEY_CLASSES_ROOT, HKEY_CURRENT_USER, HKEY_LOCAL_MACHINE, and HKEY_USERS. We'll go through them from most important to the hacker to least important to the hacker.

First and formost is the HKEY_LOCAL_MACHINE subtree. It contains five different keys. These keys are as follows:

The second most important main key is HKEY_USERS. It contains a subkey for each local user who accesses the system, either locally or remotely. If the server is a part of a domain and logs in across the network, their subkey is not stored here, but on a Domain Controller. Things such as Desktop settings and user profiles are stored here.

The third and fourth main keys, HKEY_CURRENT_USER and HKEY_CLASSES_ROOT, contain copies of portions of HKEY_USERS and HKEY_LOCAL_MACHINE respectively. HKEY_CURRENT_USER contains exactly would you would expect, a copy of the subkey from HKEY_USERS of the currently logged in user. HKEY_CLASSES_ROOT contains a part of HKEY_LOCAL_MACHINE, specifically from the SOFTWARE subkey. File associations, OLE configuration and dependency information.

09-2. What are hives?

Hives are the major subdivisions of all of these subtrees, keys, subkeys, and values that make up the Registry. They contains "related" data. Look, I know what you might be thinking, but this is just how Microsoft divided things up -- I'm just relaying the info, even I don't know exactly what all the advantages to this setup are. ;-)

All hives are stored in %systemroot%\SYSTEM32\CONFIG. The major hives and their files are as follows:

Hive                         File      Backup File
---------------------------  ------    ------------
                             ADMINxxx  ADMINxxx.LOG

Hackers should look for the SAM file, with the SAM.LOG file as a secondary target. This contains the password info.

09-3. Why is the Registry like this and why do I care?

Who the hell knows why it's this way? ;-)

The main reason is a step towards central administration and combining all that crap from SYSTEM.INI, WIN.INI, and other "legacy" Windows 3.x config stuff into one database. Then nice and neat individual GUI applications could be used to manipulate the data contained inside. And with the idea of a "domain" there are some "centralized" functionalities that are a little more convenient.

Is it better than Windows 3.x? This is debatable, although in my personal opinion I'd say yes. Were the design functions met? Probably not. While the Registry tries to be all things to all subcomponents of a domain, it does tend to smell like there were too many cooks in Microsoft's kitchen and simply not enough spoons. Some functions seem to be well suited for the Registry, some not. It is certainly not "portable" like Novell's NDS, that is you will probably never find the Registry running on a Unix system, whereas Novell's NDS is a much simpler design and is quite portable. Both schemes have their place -- NDS does not contain or manage OS info at the Desktop level and the Registry does.

Who wins? My guess is the people currently offering training classes in any modern OS are probably loving this because it is so complex, therefore it is guaranteed income. And hackers also win, because this is a complex environment where one wrong parameter setting or one Hot Fix not loaded could mean free and easy access.

My main advice to hackers is to play around with the Registry before the attack, because as you go further and further into an NT environment, you stand more chances of screwing things up, which is an easy way to make yourself known.

09-4. What do I do with a copy of SAM?

You get passwords. First use a copy of SAMDUMP.EXE to extract the user info out of it. You do not need to import this data into the Registry of your home machine to play with it. You can simply load it up into one of the many applications for cracking passwords, such as L0phtCrack. See section 3 for more info on NT passwords and cracking them.

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