3 ms·

Sounds to me like the author is essentially bemoaning a presumed lack of an invalidation mechanism, and thus declares "Bearer tokens considered harmful".

rstuart4133 5y ago
I don't think so. He is bemoaning the lack of mutual authentication. Once the token is handed out the server has no guarantee on later uses it's dealing with the thing it's handed to, and in some ways worse on later uses the user has no guarantee it's dealing with the server than gave it to him. Bearer tokens are no different to a password in that way. Netflix is currently battling shared passwords, and people regularly have their passwords stolen by a site impersonating the other end. Invalidation is only useful if you know the bearer token has been stolen or compromised so it doesn't solve them problem. It's no different to demanding your users change their passwords after a leak has been publicised. And besides - it's already possible to keep a registry of invalid tokens, just a it's possible to set a "password must be changed at next login" flag, so invalidation is possible now. But - the article seems to totally ignore the improvement short lived tokens makes to the situation. If the token only live for 15 minutes, the damage it can do is presumably limited. Still, the point remains - if you could replace a bearer token with something that did mutual authentication on every exchange it be much more secure. Conceptually, it's not even that difficult. IPSec effectively does it now for every packet sent. You "just" need to build IPSec like mechanisms into every exchange. Actually it's not that hard - with a standardised protocol app developers could use it without much change. But there doesn't appear to be much movement in that direction. Somewhat harder is "mutually authenticate with what". If the threat model is "someone hacks your computer, and steals the credentials", then it has to be tied to something unhackable that needs to be physically stolen to get any improvement. IPSec doesn't address the problem. Sure, you can authenticate against a certificate, but unless someone has going to the trouble of using a HSM that certificate is really just another long lived bearer token that can be stolen. That can be fixed. One can imagine a person using a FIDO2 key to authenticate themselves, but all the FIDO2 key does is authorised the TPM in their device to act on their behalf for a while, and the TPM establishes a trust relationship with the servers HSM and somehow tying that all together so every packet exchanges is authenticated with that trust relationship. But now we are talking real complex multilayer protocols. Such protocols would be far better than what we have now security wise, but it's a huge job. If mjg59 wants that world he would probably be better off doing some social engineering and collecting together a group to write a spec everyone can stomach, not whining about it on the internet.
- zshrdlu 5y ago
  The device can be snatched along with the FIDO2 key...
  - vladvasiliu 4y ago
    Some years ago there were some guys who implemented FIDO2 on an iPhone (Krypt.co, now bought by Akamai). Sure, people could steal your phone at the same time they steal your laptop. But it's still somewhat less likely, since the phone isn't designed to be plugged in 24/7 in your laptop's USB port, unlike the YubiKey Nano, for example.

rstuart4133 5y ago

I don't think so. He is bemoaning the lack of mutual authentication. Once the token is handed out the server has no guarantee on later uses it's dealing with the thing it's handed to, and in some ways worse on later uses the user has no guarantee it's dealing with the server than gave it to him. Bearer tokens are no different to a password in that way. Netflix is currently battling shared passwords, and people regularly have their passwords stolen by a site impersonating the other end. Invalidation is only useful if you know the bearer token has been stolen or compromised so it doesn't solve them problem. It's no different to demanding your users change their passwords after a leak has been publicised. And besides - it's already possible to keep a registry of invalid tokens, just a it's possible to set a "password must be changed at next login" flag, so invalidation is possible now. But - the article seems to totally ignore the improvement short lived tokens makes to the situation. If the token only live for 15 minutes, the damage it can do is presumably limited. Still, the point remains - if you could replace a bearer token with something that did mutual authentication on every exchange it be much more secure. Conceptually, it's not even that difficult. IPSec effectively does it now for every packet sent. You "just" need to build IPSec like mechanisms into every exchange. Actually it's not that hard - with a standardised protocol app developers could use it without much change. But there doesn't appear to be much movement in that direction. Somewhat harder is "mutually authenticate with what". If the threat model is "someone hacks your computer, and steals the credentials", then it has to be tied to something unhackable that needs to be physically stolen to get any improvement. IPSec doesn't address the problem. Sure, you can authenticate against a certificate, but unless someone has going to the trouble of using a HSM that certificate is really just another long lived bearer token that can be stolen. That can be fixed. One can imagine a person using a FIDO2 key to authenticate themselves, but all the FIDO2 key does is authorised the TPM in their device to act on their behalf for a while, and the TPM establishes a trust relationship with the servers HSM and somehow tying that all together so every packet exchanges is authenticated with that trust relationship. But now we are talking real complex multilayer protocols. Such protocols would be far better than what we have now security wise, but it's a huge job. If mjg59 wants that world he would probably be better off doing some social engineering and collecting together a group to write a spec everyone can stomach, not whining about it on the internet.

zshrdlu 5y ago
The device can be snatched along with the FIDO2 key...
- vladvasiliu 4y ago
  Some years ago there were some guys who implemented FIDO2 on an iPhone (Krypt.co, now bought by Akamai). Sure, people could steal your phone at the same time they steal your laptop. But it's still somewhat less likely, since the phone isn't designed to be plugged in 24/7 in your laptop's USB port, unlike the YubiKey Nano, for example.