[NTLUG:Discuss] Would this effect Samba servers...

[Richard Geoffrion]

provided a port to linux was made?

http://www.securityfocus.com/templates/article.html?id=195

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An application called SMBRelay, written by The Cult of the Dead Cow's Sir Dystic, exploits a design flaw in the SMB (Server Message Block) protocol on Win NT/2K boxes, easily enabling an attacker to interpose himself between the client and the server. 

The program enables access to the server using the client's authentication by acting as a 'man in the middle' to both. For this reason it's quite difficult to defend against, unless a user blocks port 139 -- which is needed for NetBIOS sessions and therefore not practical for networked boxes -- or by using NTLMv2 which employs 128bit encrypted keys and eliminates LANMAN (NT LAN Manager, or NTLM) hashes for NT clients. 

However, if port 139 is available and the network is enabled without NTLMv2 -- a situation which probably describes hundreds of thousands of boxes connected to the Net -- the SMBRelay program will likely work. 

In that case, "the target's client is disconnected and the attacker remains connected to the target's server as whatever user the target is logged in as, hijacking the connection," the author explains. 

"SMBRelay collects the NTLM password hashes transmitted and writes them to hashes.txt in a format usable by L0phtcrack so the passwords can be cracked later." 

A second version of SMBRelay which works across any protocol NetBIOS is bound to is also available on the SMBRelay Web page cited above. 
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