Does a known security issue allow ssh login via system accounts?

[Michael Ströder]

On 3/7/22 17:14, Whit Blauvelt wrote:
> Found the culprit: me. I was stupid enough to install and configure for
> libpam-google-auth, given a company mandate to 2FA all connections with
> admin access,

libpam-google-auth and other similar PAM modules require to store the 
token's shared secrets on the server. If your system gets hacked and 
shared secrets are stolen the attacker can generate an arbitrary amount 
of valid OTP values. And if you use the same shared secrets on multiple 
servers the security impact will be broad.

=> Don't use that.

> Has there been consideration
> of adding 2FA to OpenSSH that doesn't require enabling PAM? Public keys and
> IP restrictions seem enough to me.

Use the new FIDO key type.

Or use short-term OpenSSH user certificates issued by a secured SSH-CA 
which uses 2FA for user authc.

Ciao, Michael.