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Re: [NSE] Several changes to mssql.lua and SQL Server scripts
From: Patrik Karlsson <patrik () cqure net>
Date: Sat, 26 Feb 2011 11:04:17 +0100


On Feb 25, 2011, at 23:31 , Chris Woodbury wrote:

On Fri, Feb 25, 2011 at 1:53 PM, Patrik Karlsson <patrik () cqure net> wrote:

On Feb 25, 2011, at 00:15 , Chris Woodbury wrote:
Based on all of that, I have a few comments:
* Now that we have instance-name and instance-port, I'm not sure that it's intuitive that the way to hit all 
instances is by specifying instance-name=all, especially considering the case where there are instances we don't 
know the names of. How about having a script argument like mssql.all-instances?
I've added a instance-all argument to align better with the other names. Does that make sense?
 
Good idea.
 
* I really like the idea that it's now possible to use SQL Server as a proxy for doing Windows password testing. 
However, I think we should put up some hurdles for the user. Virtually all the Windows networks I've worked with 
have had account lockout policies in place, and I'm concerned that someone could accidentally end up brute-forcing 
a domain and locking out a bunch of accounts. I think we ought to add a script argument to enable it.
At first, I didn't understand the problem here, as you previously wrote that you modified the script to abort once it 
detected a lockout.
When I tested it I noticed what happened, and that there's no way of detecting that an account has been locked out 
based on the error message returned by the server.
I agree that there's a risk of locking out a number of accounts, potentially the whole domain, if you run the script 
without knowing what your doing or how it works.
Either we document this with a few exclamation marks, or we simply fail to start the script (if Windows 
authentication is used) and return an explanation why and instructions how to proceed.
We could use an argument that tells the script how many attempts to perform for each account, if unset and the 
authentication method is set to Windows, the script won't start.
How about that?
 
Actually, since you mention it, it might be nice to have an "only do this many attempts" argument for SQL Server 
authentication as well, since those can also have lockouts. But maybe that's just something the user should control 
with the password database (incidentally, the brute script now tries the username as the password - should that be 
configurable?).
Anyway, I'd be fine with doing something like that for Windows at least, or maybe just a 
ms-sql-brute.brute-windows-accounts argument, so that it's explicit. I think either would be fine, as long as it's an 
extra step that is required and is only applicable for Windows authentication.
I think controlling the amount of tries should be done by the number of entries in the password database. 
Since we detect account lockouts when sql authentication is used, we don't need an additional hurdle here in my opinion.

I've made the following changes to the ms-sql-brute script:
* If the script is started ONLY with the mssql.domain argument, it returns the following message:
| ms-sql-brute: 
|   Windows authentication was enabled but the argument
|   ms-sql-brute.brute-windows-accounts was not given. As there is currently no
|   way of detecting accounts being locked out when Windows authentication is 
|   used, make sure that the amount entries in the password list
|_  (passdb argument) are at least 2 entries below the lockout threshold.

When the ms-sql-brute.brute-windows-accounts argument is given it runs as expected.
Regarding changes to the ms-sql-brute script I would like to re-write it so that it uses the brute library I wrote a 
while back. But let's merge this first :)

 
Let me know what you think about all of that. In the meantime, I'm going to do some documentation.
Great!
 
I took a shot at this in the attached patch; let me know what you think. There's also a small bugfix in there in 
mssql.lua, where I changed a "host" to "instance.host", which fixed a bug for broadcast-ms-sql-discover.nse
I've applied it but it failed on the ms-sql-discover script, so I did that one manually. 
Also it removed the change to ms-sql-brute which makes it work together with Windows authentication, so I added that 
again.

I've done a bunch of testing too and unless there's something else, I think we should try to merge this?

//Patrik
--
Patrik Karlsson
http://www.cqure.net
http://www.twitter.com/nevdull77

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