SSH Vulnerability and the Future of SSL

iamchris writes "Growing complacent in regards to security is dangerous. I've become more and more dependant on the SSL-type tools for my security... ssh itself, ssl for my web content, scp, sftp, etc... We all know nothing is 100% secure (or if you don't, God help you). An article on Security Focus cites a vulnerability with SSH and passwords. We usually type them in letter-by-letter. A lot of information can be gleaned from the timing of the keystrokes and some (relatively simple) packet decoding. Is there a better alternative to SSL based tools (Perhaps TLS)? Is there anything that can be done with the clients help with the small packet issue?"

Comments

Not about login password

[crucini]

This is not about intercepting the ssh login password. It's about interceping passwords entered during an ssh session. Here is the relevant code from sshconnect1.c in OpenSSH:
for (i = 0; i < options.number_of_password_prompts; i++) {
if (i != 0)
error("Permission denied, please try again.");
password = read_passphrase(prompt, 0);
packet_start(SSH_CMSG_AUTH_PASSWORD);
ssh_put_password(password);
memset(password, 0, strlen(password));
xfree(password);
packet_send();
packet_write_wait();
type = packet_read(&payload_len);
if (type == SSH_SMSG_SUCCESS)
return 1;
if (type != SSH_SMSG_FAILURE)
packet_disconnect("Protocol error: got %d in response to
passwd auth", type);
}

Many people do not understand this. Some believe they are protecting themselves from this risk via RSA authentication. Of course they're not, because the risk only affects passwords in session:

1. gorf: My solution is simply not to use passwords at all; I use RSA keys exclusively...
2. SagSaw: The best way I can think of is to use the RSA key authentication method. A RSA key pair is used to authenticate, rather than a password. This way, the password is never typed over the network connection.
3. Pinball Wizard: Well, if you use RSA you don't need to type a password so that would solve that particular problem.
   
4. subsolar2: I use RSA authentication for remote access, and have since day one. So the only real worry is somebody getting a copy of my private key...
   
5. Greyfox: As has been noted, RSA is the way to go, at least with SSH authentication...
   

Others think that a GUI client is more secure entering a password in a dialog box suggests batch processing:

1. stripes: My Java ssh client happens to have "gotten it right" not because I'm smarter then other ssh client authors but because I had a dialog box to ask for the password.
   
2. Hyperbolix: Teraterm ... has several SSH extensions. I beleive one of them has you type in the password all at once and then sends it as a single string, which means that key timing can't be determined.
3. rgmoore: I think that most Windows terminal emulators have similar functionality. It seems like a very simple step to take to help preserve passwords.
4. garcia: don't most GUI terminal packages (including MacSSH, etc) all send it as a single string (SecureCRT)?
5. Rimbo: ...I use the free ttssh extension to the freeware terminal program Tera Term. When it asks you for a password, it captures everything in a dialog box, and sends the password as one chunk.
   
6. Jormundgard: Also, every SSH program I've used in windows takes in the whole password before sending it along.

The very few who got it:

1. Ethan: It's a moot point with SSH anyway, because SSH transmits the password in one chunk as far as I know...
2. Todd Knarr: I think this applies only to passwords typed during an SSH session, not the password during the authentication phase.
3. rtj: There seems to be some confusion as to the nature of this attack on ssh...All ssh implementatons send your password in one packet