Password managers with U2F security risks

Question

After a lot of research about password manager and a lot of reference obtained from this discussion How safe are password managers like LastPass? I come to the conclusion that password managers have some really scary point of failure, if my machine or mobile device is compromised when I use my master password and the U2F key to unlock the password manager (I am thinking something like yubikey or nitrokey) then all of my password can be stolen, even the ones that I use the less (like amazon account with my Credit Card information saved).

Reading the discussion and other opinions I got the impression that everyone says "If you lose the security of your machine than you are already ******", but there are cases when that isn't really true, think about the password that I use only a few times per year, like from online stores but with my CC credentials, in the time from the begin of the infection and the time I use the password I could get rid of the malware (formatting, antivirus) or I could use the password on another machine and the malware never gets this information. With a password manager every password saved can be stolen.

So, I was thinking that the best way to use a password manager is to:

-never save critical password like bank account

-never let the password manager "open" (logged in)

-never use the autocomplete, even if the clipboard is another place unsecure and in this discussion tylerl had a point for the risk of fake sites Does the average user really need a password manager? But I read about some attacks via browser that can access even to other password without a trace, so better safe than sorry.

So reading the functionality for some of the most famous password managers, like lastpass or keepass, I was searching for a chance to decrypt only the single password needed, so if the machine is compromised only this password can be stolen. But it looks like it is impossible.

It's possible to add another layer of security?

What if I use an external drive to save the offline archive, with a different file system and encryption in read-only mode, that could help?

I know, I am a little paranoid, but when I am going to use some new software o practice I want to use the most secure and correct way to do it. So now I am confused and worried, I want a relatively simple way to access to my passwords but really difficult for others to get their hands on my data.

Sorry for my English

Answer 1

I think the point of the saying "if attackers own your machine then you are already screwed" is showcased with your question. You don't want your password manager to decrypt anything except the single password you're requesting. But any malware on your system can intercept and change that request. This theoretical malware can tell your password manager to provide it with all decrypted data while still giving you the impression that only one password was decrypted.

Once your machine is owned you shouldn't trust it to perform any function that can be compromised. In reality this type of malware should be more difficult to create given its complexity, but you may not want to rely on that obstacle given your level of paranoia.

What you may prefer is a device separate from your computers or mobile devices to manage your passwords. When you need a password you authenticate to the trusted device, read off that particular password, and enter it on the potentially compromised device. Your password store is essentially air gapped, and you can focus more effort on preventing that device from being compromised. That may not meet your other criteria of being simple.

Answer 2

What you are referring to is a "con" in the argument for the pros and cons of Password Managers in general.

Password Managers do present a single point of failure -- in that if the manager is compromised, all the assorted credentials within also are compromised.

While this is a risk, it must be looked at in view of the fact that password managers mitigate numerous other risks, notably password re-use, and enforcing the use of strong and unique passwords.

If someone uses the same or similar password for many sites, if one of those sites is compromised, then those credentials can be retried on other sites. Password Managers help mitigate this vulnerability, and they also decrease the surface area so that one would have to compromise an individual password manager, rather than a site with many assorted users, to get credentials.

You can mitigate the single point of failure risk by securing high-value accounts using two factor authentication with a separate token (e.g. smartphone, Google Authenticator, separate YubiKey). Thus your password manager will only have access to one-half of the credentials needed to login.

You must personally weigh the pros/cons of each approach and see what mitigation strategies (e.g. 2FA) you want to put in place. However, for most users, a password manager will greatly increase security by mitigating attack vectors and decreasing attack surface areas; moreso than it increases risk by creating a potential single point of failure.

Answer 3

If you follow your own logic, the best way to stay secure is not to use a computer at all! Everything you do is a risk, the job is to manage the risk and make it acceptable, not to try and remove it completely. That way lies madness - literally.

The purpose of password managers is to manage passwords, of course there is some risk in concentrating this into a single application. While in theory it is possible to only decrypt a single entry at a time, that implies that you would have to have a different password for each?!

The truth is that password managers will take whatever steps they can to prevent access to unlocked data except through their own interfaces but nothing will ever totally eliminate the problem.

LastPass in fact has a OTP process for using it on untrusted computers so you could always use that if you like - but the process is painful if you use it all the time and you would quickly give up I think.

There are a couple of ways that you could, more practically improve security though if you are really paranoid.

First, make sure that you lock/logout the password manager as soon as you can. It means that you have to log back in every time but at least the db stays encrypted most of the time.

Alternatively, move to a paper password scheme such as the one put forward by Steve Gibson. Perfect Paper Passwords.

Otherwise, I recommend taking a step back and thinking about the actual risks. Will you be in a high-risk environment? Do you handle particularly sensitive or valuable information? If so, you might be right to take extra precautions though password management is only one of many you should take.

If you are not in that situation, follow safe practice with your PC and then use a password manager because having a few passwords online is far more likely than having a password manager compromised.

Answer 4

You have some options. As you say, generally LastPass and similar password managers, along with browser sync in browsers like Chrome trust the computer for a time once you've identified yourself, meaning that if someone gets your laptop still logged in, they can access it.

LastPass has an 'always ask me' setting - I suspect other managers do too.

In addition, you can take steps to protect the laptop itself : have an autolock policy so that if you leave it alone it locks itself after a short time; ensure the laptop disk(s) are encrypted - if using MacOS, enable File Vault; have a strong password for login to the OS. If they can't get to the running password manager, they cannot compromise it.

As well, truly critical sites you may wish to not include in the password manager, though I would argue the increased password length that is possible with a password manager probably reduces the danger more than the risk a password manager does.

All of this assumes, of course, your password manager password is excellent - I recommend a long(ish) phrase that contains uncommon words. Adding a few numbers or special characters to that phrase is a bonus.