RE: sshd for windows
From: Chris Berry (compjma_at_hotmail.com)
Date: 06/20/03
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To: security-basics@securityfocus.com Date: Fri, 20 Jun 2003 12:02:53 -0700
>From: "Depp, Dennis M." <deppdm@ornl.gov>
>NTLMv2 is an encryption method. (Granted it is weak, but it still is
>encrypted.) By default, Microsoft Telnet uses NTLM to encrypt the
>password. This means the only client that can access the server is the
>Microsoft telnet that comes with Windows 2000. You can setup a Windows
>2000 server with the default installation of telnet and see that the
>password is encrypted.
Ok, it looks like I was partially wrong, here's what microsoft has to say:
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What’s NTLM?
NTLM (NT LanMan) is an authentication process that’s used by all members of
the Windows NT family of products. Like its predecessor LanMan, NTLM uses a
challenge/response process to prove the client’s identity without requiring
that either a password or a hashed password be sent across the network.
How does challenge/response work?
When the authentication process begins, the user’s system (client) sends a
login request to the telnet server. The server replies with a randomly
generated “token” (or challenge) to the client. The client hashes the
currently logged-on user’s cryptographically protected password with the
challenge and sends the resulting “response” to the telnet server.
The telnet server receives the challenge-hashed response and compares it to
what it knows to be the appropriate response. (The server takes a copy of
the original token – which it generated – and hashes it against what it
knows to be the user’s password hash from its own user account database.) If
the received response matches the expected response, the user is
successfully authenticated to the host.
Is my password being sent across the network during NTLM authentication?
No. NTLM authentication does not send the user’s password (or hashed
representation of the password) across the network. Instead, NTLM
authentication utilizes challenge/response mechanisms to ensure that the
actual password never traverses the network.
----------------------------------------------------------------------------------------------------------------------------------------------
Its' still nowhere near as secure as using SSH, but it's better than the
plain text transmission I was talking about. I also did a packet capture
test and confirmed this. Be warned however that this feature can be
disabled, so you're not automatically safe.
Chris Berry
compjma@hotmail.com
Systems Administrator
JM Associates
"Within every man beats a heart of darkness." --The Shadow
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