SMBRelay and SMBRelay2 are
computer program
A computer program is a sequence or set of instructions in a programming language for a computer to Execution (computing), execute. It is one component of software, which also includes software documentation, documentation and other intangibl ...
s that can be used to carry out
SMB man-in-the-middle (mitm) attacks on
Windows
Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...
machines. They were written by
Sir Dystic of
Cult of the Dead Cow
Cult of the Dead Cow, also known as cDc or cDc Communications, is a computer hacker and DIY media organization founded in 1984 in Lubbock, Texas. The group maintains a weblog on its site, also titled " ult of the Dead Cow. New media are relea ...
(cDc) and released March 21, 2001 at the
@lantacon convention in
Atlanta
Atlanta ( ) is the List of capitals in the United States, capital and List of municipalities in Georgia (U.S. state), most populous city in the U.S. state of Georgia (U.S. state), Georgia. It is the county seat, seat of Fulton County, Georg ...
,
Georgia
Georgia most commonly refers to:
* Georgia (country), a country in the South Caucasus
* Georgia (U.S. state), a state in the southeastern United States
Georgia may also refer to:
People and fictional characters
* Georgia (name), a list of pe ...
. More than seven years after its release, Microsoft released a patch that fixed the hole exploited by SMBRelay. This fix only fixes the vulnerability when the SMB is reflected back to the client. If it is forwarded to another host, the vulnerability can be still exploited.
SMBRelay
SMBrelay receives a connection on
UDP port
A port is a maritime facility comprising one or more wharves or loading areas, where ships load and discharge cargo and passengers. Although usually situated on a sea coast or estuary, ports can also be found far inland, such as Hamburg, Manch ...
139 and relays the packets between the client and server of the connecting Windows machine to the originating computer's port 139. It modifies these packets when necessary.
After connecting and authenticating, the target's client is disconnected and SMBRelay binds to port 139 on a new
IP address
An Internet Protocol address (IP address) is a numerical label such as that is assigned to a device connected to a computer network that uses the Internet Protocol for communication. IP addresses serve two main functions: network interface i ...
. This relay address can then be connected to directly using "net use \\192.1.1.1" and then used by all of the networking functions built into Windows. The program relays all of the SMB traffic, excluding negotiation and authentication. As long as the target host remains connected, the user can disconnect from and reconnect to this
virtual IP.
SMBRelay collects the
NTLM
In a Windows network, NT (New Technology) LAN Manager (NTLM) is a suite of Microsoft security protocols intended to provide authentication, integrity, and confidentiality to users. NTLM is the successor to the authentication protocol in Microsoft ...
password
hash
Hash, hashes, hash mark, or hashing may refer to:
Substances
* Hash (food), a coarse mixture of ingredients, often based on minced meat
* Hash (stew), a pork and onion-based gravy found in South Carolina
* Hash, a nickname for hashish, a canna ...
es and writes them to hashes.txt in a format usable by
L0phtCrack for cracking at a later time.
As port 139 is a privileged port and requires
administrator
Administrator or admin may refer to:
Job roles Computing and internet
* Database administrator, a person who is responsible for the environmental aspects of a database
* Forum administrator, one who oversees discussions on an Internet forum
* N ...
access for use, SMBRelay must run as an administrator access account. However, since port 139 is needed for
NetBIOS
NetBIOS () is an acronym for Network Basic Input/Output System. It provides services related to the session layer of the OSI model allowing applications on separate computers to communicate over a local area network. As strictly an API, Net ...
sessions, it is difficult to block.
According to Sir Dystic, "The problem is that from a marketing standpoint, Microsoft wants their products to have as much
backward compatibility
In telecommunications and computing, backward compatibility (or backwards compatibility) is a property of an operating system, software, real-world product, or technology that allows for interoperability with an older legacy system, or with Input ...
as possible; but by continuing to use protocols that have known issues, they continue to leave their customers at risk to exploitation... These are, yet again, known issues that have existed since day one of this protocol. This is not a bug but a fundamental design flaw. To assume that nobody has used this method to exploit people is silly; it took me less than two weeks to write SMBRelay."
[Greene, Thomas C. ]
Exploit devastates WinNT/2K security
" ''The Register
''The Register'' (often also called El Reg) is a British Technology journalism, technology news website co-founded in 1994 by Mike Magee (journalist), Mike Magee and John Lettice. The online newspaper's Nameplate_(publishing), masthead Logo, s ...
'' online edition, April 19, 2001. Retrieved August 20, 2005.
SMBRelay2
SMBRelay2 works at the NetBIOS level across any protocol to which NetBIOS is bound (such as
NBF or
NBT). It differs from SMBrelay in that it uses NetBIOS names rather than IP addresses.
SMBRelay2 also supports man-in-the-middling to a third host. However, it only supports listening on one name at a time.
See also
*
Pass the hash
In computer security, pass the hash is a hacking technique that allows an attacker to authenticate to a remote server or service by using the underlying NTLM or LanMan hash of a user's password, instead of requiring the associated plaintext passw ...
References
External links
The SMB Man-In-the-Middle Attack by Sir Dystic
How to disable LM authentication on Windows NT- lists affected operating systems
Your Field Guide To Designing Security Into Networking ProtocolsExtended Protection for Authentication
{{Cult of the Dead Cow
Windows security software
Computer security exploits
Internet Protocol based network software
Cult of the Dead Cow software