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This is good. There's not much information around on this topic, and often roles seem only vaguely hinted at. The lab I work at recently had a "worry" during r

This is good. There's not much information around on this topic, and often roles seem only vaguely hinted at. The lab I work at recently had a "worry" during recent attacks on UK science infrastructure that someone might have compromised an unknown private key someone might have stored on a third part server. The institutional response was to switch to password-based ssh only for a month (so lots of people used sshpass...) and then revoke - at the bastion - every single key listed in every single authorized_keys for every one of thousands of users in the system, before turning key access on again. I've wondered why they didn't switch to an ssh certificate system. My best guess is the complication, maintenance, and risk profile of setting up a secure key-signing system to do this signing automatically - presumably this acts as a single point-of-failure for compromising the entire network.

gnufx 6y ago
I've not seen any rationale why sites haven't done something sensible. Sensible, like allowing automation without storing your password to use sshpass, for instance; then if you insist on MFA, that can be done when issuing an ephemeral certificate. "Certificate" might bring back bad memories of Globus et al, but that was different, and I haven't seen it articulated. The general response to those compromises has been a disaster area. Especially as (in the absence of any post mortem, as far as I know) the attack presumably involved the general password-spraying that was happening around then. Users were made to look responsible and suffer because systems had local privilege escalations due to poor management -- which, to be fair, might be due to relying on cluster vendors who "take security very seriously", as they say. That has been around the top of the threat list for decades too, it's just that it's now much larger scale. Then you got private keys purged that might be used to access systems on other sites with less risk than typing passwords on insecure systems -- arbitrarily deleting users' data.
AA1B7B76 6y ago
I have given up on OpenSSH's built-in certificate handling because it does not properly support revocation. It's not possible to have 100% of your keys on a short duration, so you have to cook up a revocation system. That's not my idea of a fun time. Auditing keys on disk is much less trouble than properly managing CRLs.
GekkePrutser 6y ago
Why not use smart cards? Then the key can't be copied. Only physically stolen but you'd need the pin as well and it works be noticed it's missing.

gnufx 6y ago

I've not seen any rationale why sites haven't done something sensible. Sensible, like allowing automation without storing your password to use sshpass, for instance; then if you insist on MFA, that can be done when issuing an ephemeral certificate. "Certificate" might bring back bad memories of Globus et al, but that was different, and I haven't seen it articulated. The general response to those compromises has been a disaster area. Especially as (in the absence of any post mortem, as far as I know) the attack presumably involved the general password-spraying that was happening around then. Users were made to look responsible and suffer because systems had local privilege escalations due to poor management -- which, to be fair, might be due to relying on cluster vendors who "take security very seriously", as they say. That has been around the top of the threat list for decades too, it's just that it's now much larger scale. Then you got private keys purged that might be used to access systems on other sites with less risk than typing passwords on insecure systems -- arbitrarily deleting users' data.

AA1B7B76 6y ago

I have given up on OpenSSH's built-in certificate handling because it does not properly support revocation. It's not possible to have 100% of your keys on a short duration, so you have to cook up a revocation system. That's not my idea of a fun time. Auditing keys on disk is much less trouble than properly managing CRLs.

GekkePrutser 6y ago

Why not use smart cards? Then the key can't be copied. Only physically stolen but you'd need the pin as well and it works be noticed it's missing.