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I’ve seen a compromised machine whose sshd had been replaced with a trojan that saved all passwords entered into it. Some investigation revealed that sshd modif

by anjbe 5y ago

I’ve seen a compromised machine whose sshd had been replaced with a trojan that saved all passwords entered into it. Some investigation revealed that sshd modification to be part of a standard script kiddie toolkit. Are you 100% sure that every machine you log into remotely with your very strong password isn’t logging that password? That’s one advantage of keys.

Enginerrrd 5y ago
Perhaps I'm missing something? I don't understand the issue. If the machine you're logging into (running sshd) is already compromised, it's... already compromised. I don't recycle passwords, so what is the risk? And if the device on which you're running your ssh client is already compromised, it doesn't matter whether you use a key or password, its the same thing. Can you explain the threat a bit more?
- traceroute66 5y ago
  > And if the device on which you're running your ssh client is already compromised, it doesn't matter whether you use a key or password, its the same thing. Whoa there sunshine. Put your SSH keys on a USB HSM (Yubikey or Nitrokey) and nobody is ever going to be able to extract the private key. Added bonus, put it on a USB HSM with touch auth (e.g. Yubikey) and nobody will ever be able to use the key without you knowing it (because you have to physically touch it).
  - Enginerrrd 5y ago
    >Put your SSH keys on a USB HSM (Yubikey or Nitrokey) and nobody is ever going to be able to extract the private key. Except you. To run through a compromised machine... Perhaps I don't quite understand how it works, but I don't see how this setup negates that issue. Once you plug it into the compromised machine and allow access to it with whatever touch-authentication or w/e, I can't imagine you could keep it secret from the attacker on the compromised machine. But maybe it's encrypting the key on the device?
- anjbe 5y ago
  > I don't recycle passwords That’s good. I think you’re probably in the minority though. There are other ways unique passwords can be compromised. I see passwords accidentally entered into IRC windows about once a month. And even if you have perfect discipline at using unique passwords, that’s not something you can enforce on anyone else logging into your machine. Maybe someone will chime in with strategies to run ssh from a wrapper that loads a unique password from a password manager with no risk of reuse or entry into the wrong window, or something. But at that point, your complaint about being locked out without the necessary files would apply—might as well use a key, which is simpler and provides strong security with no rigamarole.

by anjbe 5y ago

Enginerrrd 5y ago

Perhaps I'm missing something? I don't understand the issue. If the machine you're logging into (running sshd) is already compromised, it's... already compromised. I don't recycle passwords, so what is the risk? And if the device on which you're running your ssh client is already compromised, it doesn't matter whether you use a key or password, its the same thing. Can you explain the threat a bit more?

traceroute66 5y ago
> And if the device on which you're running your ssh client is already compromised, it doesn't matter whether you use a key or password, its the same thing. Whoa there sunshine. Put your SSH keys on a USB HSM (Yubikey or Nitrokey) and nobody is ever going to be able to extract the private key. Added bonus, put it on a USB HSM with touch auth (e.g. Yubikey) and nobody will ever be able to use the key without you knowing it (because you have to physically touch it).
- Enginerrrd 5y ago
  >Put your SSH keys on a USB HSM (Yubikey or Nitrokey) and nobody is ever going to be able to extract the private key. Except you. To run through a compromised machine... Perhaps I don't quite understand how it works, but I don't see how this setup negates that issue. Once you plug it into the compromised machine and allow access to it with whatever touch-authentication or w/e, I can't imagine you could keep it secret from the attacker on the compromised machine. But maybe it's encrypting the key on the device?
anjbe 5y ago
> I don't recycle passwords That’s good. I think you’re probably in the minority though. There are other ways unique passwords can be compromised. I see passwords accidentally entered into IRC windows about once a month. And even if you have perfect discipline at using unique passwords, that’s not something you can enforce on anyone else logging into your machine. Maybe someone will chime in with strategies to run ssh from a wrapper that loads a unique password from a password manager with no risk of reuse or entry into the wrong window, or something. But at that point, your complaint about being locked out without the necessary files would apply—might as well use a key, which is simpler and provides strong security with no rigamarole.